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Amyloidosis is a group of diseases that have a common feature where proteins behave abnormally, with the breakdown products of these proteins folding upon themselves and depositing in various organs. Hereditary transthyretin amyloidosis is caused by a genetic mutation which causes misfolding of transthyretin (TTR) proteins (which originate from the liver). There are over 100 genetic variants of hereditary amyloidosis.

One such variant, called T60A, is the most common variant in Ireland (and the UK).

Symptoms of hereditary amyloidosis, specifically the T60A variant, include a variety of peripheral neuropathic, autonomic, and cardiac maladies, including:

carpal tunnel syndrome
numbness and tingling in hands, feet, arms, and legs
muscular weakness
excessive sweating
dizziness/fainting (orthostatic hypotension)
sexual disfunction
unintentional weight loss
indigestion
acid reflux
bouts of constipation and diarrhea
fatigue
shortness of breath
leg swelling
chest pain

One Patient’s Story

“Do you have an ancestor from Donegal?” is a question frequently asked by doctors who are investigating the possibility that a patient may have hereditary amyloidosis type T60A. With its origins in a short ribbon of coastline in North-West Donegal (Ireland), the condition wandered worldwide with Irish migration.”

_{(Callaghan, Donegal Amy, 2022.)}

Donegal Ireland was one of the worst affected areas of Ireland’s “Great Hunger” of the mid to late 1800’s. 123,000 emigrants left the Donegal area between 1851-1900. A great many of them migrated to the United States, many to the Appalachian region of the country. The T60A variant, as it now appears in the United States, has been traced back to those settling in Appalachia. Sean Riley is a T60A amyloidosis patient who has ancestorial connections to Appalachia and the Donegal area.

Sean’s journey to diagnosis began in the fall of 2012 when he had bilateral carpal tunnel surgery. His job required quite a bit of typing and handwriting so he assumed that the condition was related to repetitive motion, which is a common cause of carpal tunnel syndrome. Little did he or the attending hand surgeon know that bilateral carpal tunnel syndrome may be an early neurological symptom of amyloidosis.

Concurrently, Sean started experiencing numbness in his left foot and lower left leg. He previously had vascular surgery on the left leg, and incorrectly assumed that the foot and leg numbness might be associated with nerve damage from the surgery. In actuality the numbness was due to the onset of peripheral neuropathy, yet another early symptom of the disease.

Between 2014 and 2017 he was taken to the hospital by ambulance on three separate occasions. In each instance he felt extreme dizziness and discomfort in his chest and assumed that the events were due to a cardiac issue, but no obvious signs of cardiac issues could be identified in any of the events. He now knows that what he was experiencing was orthostatic hypotension due to the onset of progressive autonomic neuropathy, another signature malady associated with the disease.

In the fall of 2017 Sean started being treated for severe acid reflux and gastrointestinal issues. Over time he had an endoscopy and colonoscopy performed, each which indicated normal results. These conditions likely indicated the onset of amyloidosis impact on nerves and tissue of the gastro-intestinal system.

Over the period of time from 2012 through 2017 Sean was seen by a hand surgeon, cardiology, oncology, endocrinology, neurology, and gastroenterology, along with his primary care physician. Nobody was able to connect the dots to amyloidosis, a product of the rarity of the disease and resulting lack of disease expertise by the general medical community.

In 2018 Sean moved overseas to Abu Dhabi to pursue a career opportunity. Shortly after arriving he started experiencing more frequent hypotensive episodes as well as progressive muscle wasting and weight loss. Fortunately for Sean the Cleveland Clinic has a hospital facility in Abu Dhabi. The attending cardiologist had a working knowledge of amyloidosis and ordered a series of tests, including an echocardiogram, a cardiac MRI, and a neuropathic evaluation, all of which concluded a preliminary positive diagnosis for the disease. As a result, the cardiologist recommended that Sean travel back to the United States and be seen at the amyloidosis center at Brigham and Women’s hospital in Boston. In February of 2019 he received a definitive diagnosis of hereditary transthyretin amyloidosis, specifically the T60A mutation. Excerpts of the confirming echocardiogram, cardiac MRI, and genetic testing results are shown below.

Echocardiogram Summary Notes

Associated Cardiac MRI Interpretation

DNA Sequencing Result

Shortly after diagnosis, Sean started treatment with a state-of-the-art FDA-approved amyloidosis drug. The treatment is administered every three weeks and is designed to slow or stop disease progression. The drug is an RNA signal blocker which stops the transthyretin proteins from misfolding and creating amyloid fibrils.

Sean continues this therapy to this day, and all indications show that disease progression has stopped. There is no cure for the disease, so he must contend with and manage the damage that has been done; however, he is thrilled that the disease progression is being kept in check.

For more information on hereditary amyloidosis worldwide, visit our blog — Click Here

Bibliography

“Donegal Amy-A Rare Inherited Disease from Ireland”, Rosaline Callaghan, Roscara Books, 2022.

“Unraveling the Lineage: The Genetic Basis of Familial ATTR Cardiomyopathy Ronald Witteles”, MD Professor of Medicine (Cardiovascular Medicine).

“Cardiac Amyloidosis Part 1: Understanding Types and Risks”, Dr. Rodney Falk, Brigham and Women’s Hospital, YouTube, July 2018.

Obi CA, Mostertz WC, Griffin JM, Judge DP. ATTR Epidemiology, Genetics, and Prognostic Factors. Methodist Debakey Cardiovasc J. 2022 Mar 14;18(2):17-26. doi: 10.14797/mdcvj.1066. PMID: 35414855; PMCID: PMC8932385.

Transthyretin Amyloidosis, or ATTR, is considered a single disease, however the diversity in its clinical presentation is staggering. In this blog, we’ll discuss some of the most common hereditary variants and how the disease manifestation differs around the world in documented hotspots.

Source: Epidemiology, Genetics, and Prognostic Factors (1)

There are two distinct forms of Transthyretin Amyloidosis (ATTR), the hereditary form (ATTRv), and the non-hereditary form (ATTR-wt) commonly referred to as wild-type amyloidosis. Disease manifestation is considered a spectrum involving aspects of cardiomyopathy, neuropathy, or more frequently a mixture of both.

Below we’ll discuss the hereditary form and the various genetic variants and how they differ based on geographical location.

WHAT IS TRANSTHYRETIN (TTR)

Transthyretin, also known as prealbumin, is a protein produced primarily in the liver that is responsible for the transport of thyroxine and retinol. Interesting enough, this is how it got its name.

In steady state, the protein circulates primarily as a tetramer (i.e., monomeric form), but unfortunately, its monomeric form is inherently amyloidogenic (prone to breakdown and formation of amyloid aggregates). Couple that with mutations that increase the amyloidogenicity of the protein, these tetramers dissociate into monomers that will misfold, aggregate, and form the insoluble fibrils (“amyloid”) that are resistant to the body’s inherent protective mechanisms like proteolysis.

SPECIFIC TTR PATHOGENIC VARIANTS

As of today, there have been over 145 reported variants related to hereditary transthyretin amyloidosis. Interestingly, these genetic variants have a tendency to cluster in both geographic and ethnic groups around the world. We’ll discuss some of the most prevalent mutations below.

Val122Ile

This is the most common TTR mutation in the United States, with a prevalence of roughly 3.4% in the African American community. The disease is primarily cardiac in nature, typically present when patients are in their 60s. It is thought that this mutation arose from the region of West Africa and has worked its way to the United States over time, where it has become the predominant form.

Val30Met

This is the most commonly recognized TTR mutation worldwide and the first TTR variant discovered. It is most commonly found in the regions of Portugal, Spain, France, Japan, Sweden, and Brazil. Interestingly, between these regions where this mutation dominates, there is variability in age of onset and parent-of-origin. For example, age of onset was found to be earlier in the Swedish population in comparison to Portugal and Japan. As for the parent-of-origin, it was found that the mother was more likely than the father to pass along the mutation (153 vs. 138), whereas in the French population the father was more likely to pass on the mutation (219 vs. 216), although not by much. The one thing these populations do have in common is this form of the disease is almost exclusively neurologic in nature.

Thr60Ala

This variant is most commonly found in the UK and Irish populations, and is also seen in the Appalachian region of the United States. This variant presents as a mixture of both cardiomyopathy and neuropathy symptoms. It seems to be that in early stages of the disease the neurologic symptoms are most prevalent, but cardiac symptoms present at diagnosis seem to indicate poorer patient outcomes.

Thr119Met

This is arguably the most interesting variant that was investigated in a large study of the Danish population. The presence of this mutation actually confers a protective benefit. When this mutation occurs along with the Val30Met mutation, it has the effect of stabilizing and delaying, even preventing transthyretin amyloidosis.

PROGNOSIS

While the prognosis is by no means near perfect, it is improving. There is continued advancement in the field of transthyretin amyloidosis, whether it be improving diagnostic methods, drug development, or a potential cure on the horizon with CRISPR gene-editing technology. Having said that, there continue to be significant barriers to diagnosis. The importance of being an astute clinician to suspect and work up for amyloidosis remains at the forefront of the challenge.

CONCLUSION

The geographic nature of this disease plays an important role in identifying and diagnosing amyloidosis. Having an understanding of how the presentation of the disease is heavily related to the patient’s ancestry and location around the world. The hardest part is suspecting amyloidosis, from there don’t forget the value of the diagnostic tools at your disposal, including genetic testing. Use this knowledge to strengthen and guide your suspicions of amyloidosis!

Over the upcoming months we’ll post blogs delving deeper into some of these variants, so stay tuned.

Thanks for reading,

Mackenzie

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SOURCES

Over the course of the past two months, we spent time discussing two of the most common hallmark symptoms of ATTR amyloidosis: cardiomyopathy and peripheral neuropathy. In this article, we’ll briefly recap both hallmark symptoms as well as bring it all together by discussing the two most common forms of ATTR amyloidosis: ATTR cardiomyopathy (ATTR-CM) and ATTR peripheral neuropathy (ATTR-PN).

To recap …

Cardiomyopathy

Cardiomyopathy is a broad term that is used to describe disease of the heart muscle, making it difficult for the heart to provide the body with an adequate blood supply. It is a common cause of sudden cardiac arrest and sudden cardiac death, which can lead to heart failure and even death.

Types of Cardiomyopathy:

Dilated Cardiomyopathy → dilation of the left ventricle prevents the heart from pumping effectively
Hypertrophic Cardiomyopathy → abnormal thickening of the heart muscle most commonly surrounding the left ventricle
Restrictive Cardiomyopathy → stiffening of the heart muscle results in an inelasticity
Arrhythmogenic Right Ventricular Dysplasia → scar tissue replaces healthy tissue of the right ventricle
Unclassified Cardiomyopathy → all other forms of cardiomyopathy fall within this category

Peripheral Neuropathy

Peripheral neuropathy, also referred to as polyneuropathy, is a very broad term used to describe damage of the peripheral nerves. Damage to these nerves most commonly causes numbness, pain, and weakness but can affect other areas of the body including, but not limited to, circulation, digestion, and urination.

Types of Neuropathy:

Motor Neuropathy → damage to the motor nerves
Sensory Neuropathy → damage to sensory nerves
Autonomic Nerve Neuropathy → damage to autonomic nerves that control involuntary functions
Combination Neuropathies → damage to a mix of 2 or 3 of these other types of neuropathies

ATTR Amyloidosis

The origin of this disease can be genetic (hATTR) or non-genetic, or “wild-type” (wtATTR). Regardless, in ATTR amyloidosis, the transthyretin (TTR) protein is misfolded and aggregates, forming amyloid fibers that deposit into tissues and organs. The deposition of protein causes organ dysfunction and can even cause organ failure and death.

ATTR-CM and ATTR-PN

Depending on the location of protein deposition, the disease is referred to in different ways. For instance, when the primary location of amyloid deposit is in the heart, the disease is referred to as ATTR cardiomyopathy (ATTR-CM). On the other hand, when the primary location of amyloid deposit is in the nerves, the disease is referred to as ATTR peripheral neuropathy (ATTR-PN).

ATTR-CM impairs the heart’s ability to pump effectively. A major challenge surrounding this disease is that symptoms of ATTR-CM are often similar to other heart conditions like enlarged heart and heart failure. This makes diagnosing the disease increasingly more difficult. Individuals with hATTR typically present symptoms in their 50s and 60s, whereas those with wtATTR may not present symptoms until their 70s and later.

Common Symptoms of ATTR-CM:

Fatigue
Swelling of legs, ankle, or abdomen
Shortness of breath with activity
Orthostatic hypotension
Difficulty breathing when lying down
Arrhythmia

ATTR-PN impairs the function of the nervous system. While amyloid most commonly builds up in the peripheral nervous system, deposition can also occur in the autonomous system. This results in a diversity of symptoms that are specific to the site of amyloid deposition. Symptom presentation is much more diverse, occurring as early as the 20s, or as late in life as the 70s.

Common Symptoms of ATTR-PN:

Carpal tunnel syndrome
Diarrhea and/or constipation
Nausea, vomiting
Loss of appetite
Sexual dysfunction
Muscle weakness
Eye problems
Orthostatic hypotension

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References:

https://www.pfizer.com/news/articles/understanding_this_rare_disease_called_attr_amyloidosis

https://www.mayoclinic.org/diseases-conditions/cardiomyopathy/symptoms-causes/syc-20370709

https://www.yourheartsmessage.com

https://healthjade.net/familial-amyloidosis/

https://my.clevelandclinic.org/health/diseases/14737-neuropathy

https://www.hopkinsmedicine.org/health/conditions-and-diseases/peripheral-neuropathy

https://www.mayoclinic.org/diseases-conditions/peripheral-neuropathy/symptoms-causes/syc-20352061

https://practicalneurology.com/articles/2021-july-aug/neuromuscular-amyloidosis

https://healthjade.net/familial-amyloidosis/

Alnylam Announces FDA Approval of AMVUTTRA™ (vutrisiran), an RNAi Therapeutic for the Treatment of the Polyneuropathy of Hereditary Transthyretin-Mediated Amyloidosis in Adults

– First and Only FDA-approved Treatment Demonstrating Reversal in Neuropathy Impairment with Subcutaneous Administration Once Every Three Months

– AMVUTTRA Met Primary and All Secondary Endpoints, with Significant Improvement in Polyneuropathy, Quality of Life and Gait Speed Relative to External Placebo

– Company Expects to Launch in Early July, with Value-Based Agreements to Accelerate Access

The FDA approval is based on positive 9-month results from the HELIOS-A Phase 3 study, where AMVUTTRA significantly improved the signs and symptoms of polyneuropathy, with more than 50 percent of patients experiencing halting or reversal of their disease manifestations.

Following yesterday’s U.S. FDA approval, people in the U.S. prescribed AMVUTTRA (vutrisiran) and their families can now enroll in Alnylam Assist, our patient support services program, to receive help accessing this new therapy. https://bit.ly/3HjOg5Q

PRESS RELEASE

Amyloidosis is a “group of diseases” that have the common feature where abnormal proteins (or in some cases normal proteins) behave abnormally, and the breakdown product of these proteins fold upon themselves, creating amyloid” fibrils” which deposit in various organs throughout the body. This potentially life-threatening disease can affect the heart, kidneys, liver, spleen, nervous system and digestive tract. (Falk, R., MD, 2018) A basic illustration of the creation of amyloid “fibrils” is shown below.

(Cleveland Clinic, 2020)

There are different types of the disease including AL or Light Chain Amyloidosis, AA Amyloidosis, Transthyretin Amyloidosis (referred to as TTR amyloidosis), and Localized Amyloidosis. TTR amyloidosis includes a hereditary type and a non-hereditary type. (Falk, R, MD, 2018)

Common symptoms of amyloidosis are shown in the following figure.

(The Canadian Amyloidosis Support Network)

Light Chain (AL) Amyloidosis

AL amyloidosis is the most common type of amyloidosis in developed countries, accounting for approximately 85% of all cases. There are approximately 3,000-5,000 new AL amyloidosis cases a year in the United States. (Falk, R., MD, 2018)

The disease usually affects the heart, kidneys, liver and nerves. This type of amyloidosis is blood related, associated with the abnormality of proteins from plasma cells associated with bone marrow. Plasma cells normally create antibodies, known as immunoglobulins, that serve to combat bacteria and viruses. Antibodies are made up of “heavy chains” and “light chains.” AL amyloidosis stems from an abnormal expansion of plasma cells. The abnormal plasma cells secrete abnormal “free light chains” (FLCs) into the bloodstream. These abnormal light chain mutations become “sticky.” The sticky light chains bind together to form amyloid fibrils which can then accumulate in various body organs, as shown below. (Sherwood, A.L.)

(Cleveland Clinic, 2020)

Diagnostic testing for AL amyloidosis includes blood testing, urine tests and biopsies. Blood and/or urine tests are used to indicate the presence of amyloid protein, however bone marrow tests or other small biopsy samples of tissue or organs are needed to positively confirm the diagnosis of amyloidosis. Specific types of blood/urine testing include:

A 24-hour urine collection to look at the level of protein in your urine sample. Excess protein in the urine may be an indication of kidney involvement.
The level of ALP (an enzyme called “alkaline phosphatase”) in your regular blood workup.
Blood tests to look for stress and strain on the heart. Cardiac biomarkers that are used include troponin T or troponin I, and NT-proBNP (which stands for N-terminal pro-brain natriuretic peptide) or BNP (brain natriuretic peptide).
Tests for abnormal antibody (immunoglobulin) proteins in the blood include the Free Light Chain Assay, which shows the level of kappa and lambda light chains in a separate blood test. The Free Light Chain Assay test is often referred to as FLC, which is an abbreviation for free light chains.
Another test for abnormal immunoglobulin can be done with blood and/or urine. It is called “immunofixation electrophoresis.”

Echocardiogram and imaging are performed so that the doctor can look for amyloid deposits in the heart, while viewing the size and shape of it and the location and extent of any impact of amyloid.

Tissue biopsy are performed to identify evidence of amyloid deposits. Tissue samples are sent to a lab for microscopic examination, where the tissue is stained with a dye called “Congo-red.” After putting it under a microscope, amyloid protein is discovered if it turns an apple-green color, resulting in a diagnosis of amyloidosis. The most common tissue sample, which is almost always involved in generating an AL diagnosis, is called a fat-pad biopsy. Fat-pad biopsies are taken from the stomach. Biopsy samples may also be taken from the liver, kidney, nerves, heart, stomach, or intestines.

Bone marrow tests are also performed. These involve the removal of some liquid bone marrow and/or the removal of bone tissue. These samples can help to determine the percentage of amyloid producing plasma cells, and when tested in the lab they can assist in identifying whether the abnormal plasma cells are producing kappa or lambda light chains. (Amyloidosis Foundation, 2021)

If treatment begins during the early onset of clinical symptoms, the overall success rate is higher, so early detection is essential.

Patients with AL amyloidosis have benefited from the recent development of new drugs for myeloma, many of which work effectively on the plasma cells that cause AL amyloidosis. In addition, the FDA approved the first drug treatment specifically for AL amyloidosis in January 2021, called DARZALEX (daratumumab). Drug combinations are more effective than single drugs in attacking the abnormal plasma cells. Drugs that may be useful include traditional chemotherapy drugs (such as melphalan, and cyclophosphamide), as well as “proteasome inhibitor” and “immunomodulator” drugs. (Amyloidosis Foundation, 2021)

Stem cell transplant is also a preferred therapy, as it can provide long-term control of the underlying disease. However, only a minority of AL patients (typically less than 25%) are eligible. (Amyloidosis Foundation, 2021)

AA Amyloidosis

AA amyloidosis results from increased levels of the circulating serum “amyloid A protein.” Amyloid A protein levels normally elevate in the bloodstream as a response to infection and inflammation. If a patient has an infection or inflammatory condition for an extended period of time (six months or more) they would be at risk for developing AA amyloidosis. The amyloidosis can arise due to chronic inflammatory and infectious conditions, including rheumatic disease, inflammatory bowel disease, tuberculosis, osteomyelitis, lupus, and hereditary fever syndromes. Amyloid deposition usually begins in the kidneys, but the liver, spleen, lymphnodes, and intestines are also commonly affected.

If a patient has been diagnosed with a chronic inflammatory disease or chronic infection and they develop high levels of protein in the urine or other associated AA symptoms, then the physician should test for AA amyloid deposition. When kidney damage occurs, it can be clinically shown as protein found in the urine (nephrotic syndrome) or impairment of kidney function.

A test involving a 24-hour urine collection can be performed to look at the level of protein in the patient’s urine. If amyloidosis is suspected in most cases a biopsy of the kidney tissue performed.

In order to identify AA amyloid, the most common diagnostic test is staining the tissue sample with antibodies that are specific to AA amyloid, the “anti-AA serum.” If the anti-AA serum result is positive then AA amyloidosis is diagnosed. Once AA amyloidosis is confirmed the primary underlying inflammatory condition should then be identified.

With AA amyloidosis it is most important to treat the underlying infection or inflammation in order to reduce the level of the precursor for the AA amyloid deposits. These treatments vary depending on the underlying condition. Some treatments that exist for inflammatory diseases include surgery on the infection or tumor, drug therapies for rheumatoid arthritis, antibiotics for chronic infection, among others.

With effective treatment of the underlying inflammation amyloid deposits have been known to reduce and nephrotic syndrome can improve. If the kidney function has become significantly impaired, it rarely recovers.

Supportive treatment is very important, including nephrology, cardiology, and neurology. (Amyloidosis Foundation, 2021)

TTR (Transthyretin) Amyloidosis

As stated earlier, TTR amyloidosis includes a hereditary type and a non-hereditary type.

Hereditary (Familial) Amyloidosis, also referred to as ATTRv amyloidosis, is associated with an inherited genetic mutation. There are various subtypes of familial amyloidosis that are associated with specific demographic groups including Portuguese, Irish, Swedish, Afro-American, and Japanese lineage.

The non-hereditary type of TTR amyloidosis, known as Wild Type Amyloidosis is a disorder predominately of older men in their 70s and beyond. This form of the disease may actually be responsible for up to 10% of male patients having heart failure due to stiff heart tissue. (Falk, R., MD, 2018)

As with AL and AA Amyloidosis, TTR Amyloidosis can manifest itself with a multitude of symptoms. In a vast majority of cases the resultant symptoms are cardiological and/or neuropathic in nature. A basic illustration of the production method for TTR amyloid fibrils is shown below.

Early diagnosis if TTR amyloidosis is essential so as to help minimize the extent of bodily tissue or system damage. First, a patient is tested to determine if they have amyloid proteins in their body. The main diagnostic testing is similar to that described above for AL Amyloidosis, including blood tests, urine tests and biopsies. If amyloidosis is confirmed but the type is not initially identified, additional tests are performed to determine the existence and variation of ATTR.

Once it is determined that there is transthyretin amyloid protein (via biopsy and Congo red staining), the specific protein needs to be identified by protein sequence analysis and DNA sequencing. A blood sample is sent to a lab where the DNA chains are analyzed. Sections of the DNA chain are checked for genetic markers of the DNA defect. Hereditary amyloidosis variations affect patients differently. It is critical to establish which variation exists in order to identify a tailored treatment plan.

Treatment of TTR amyloidosis include treating the source and symptoms. Source treatment involves slowing down, or stopping, the overproduction of amyloid at the source of the disease. Historically, liver transplant has been helpful, however, the statistics vary as to who can benefit from these transplants, with the outcome dependent largely on the specific mutation that exists in the patient. In some situations, combined heart and liver transplants have helped patients with an ATTR variant that produces cardiac problems.

In 2019, two drugs were approved for treatment of ATTR polyneuropathy associated with TTR amyloidosis in adults. The first was ONPATTRO (patisiran), a first of its kind RNA interference therapeutic drug which aims to silence the gene expression for patients with the hereditary type TTR. The second drug approved is TEGSEDI (inotersen), which reduces the production of TTR protein. Also, in 2019, VYNDAQEL and VYNDAMAX (tafamidis) were approved by the FDA for ATTR cardiomyopathy. (Amyloidosis Foundation, 2021)

There is supportive treatment for the various symptoms associated with TTR Amyloidosis, possible symptoms include peripheral neuropathy, autonomic neuropathy, cardiac and kidney problems. There are medications that can be prescribed to treat the effects of peripheral neuropathy, such as tingling or burning sensations. Many patients experience autonomic neuropathy and may require treatment for blood pressure, heart rate, digestion, and perspiration, depending on the location of the damage to the nerves. Other gastrointestinal dysfunctions may require treatment for symptoms that include poor nutritional health, diarrhea or constipation, and nausea or vomiting. (Amyloidosis Foundation, 2021)

Localized Amyloidosis

Localized amyloidosis often has a better prognosis than the types that affect one or more organ systems. Typical sites for localized amyloidosis include the bladder, skin, throat or lungs. Correct diagnosis is important so that treatments that affect the entire body can be avoided. (Mayo Clinic. 2021)

Summary

Amyloidosis is a complex multi-systemic disease where no two patients are alike. Symptoms are often vague and vary from patient to patient, even within the same disease type, making diagnosis one of the biggest hurdles for the medical community. It is not uncommon to hear from patients that it took multiple years and multiple doctors to ultimately arrive at a correct diagnosis, all the while the disease continued to progress. While treatment is type-specific, it is individualized from patient to patient depending on organ involvement.

In the words of Morie A. Gertz, M.D., M.A.C.P., of the Mayo Clinic and regarded as a leading world expert on amyloidosis.

“Thanks to the Amyloidosis Speakers Bureau, providers across the country are being instructed on techniques to suspect and recognize amyloidosis and how to efficiently make the diagnosis in a timely fashion. Incorporating testing for amyloidosis into the work flow of patients with cardiomyopathy, proteinuria, peripheral neuropathy, unexplained weight loss, and smoldering multiple myeloma has been successful.

Comprehensive education remains the best strategy to save lives for this rare disorder.”

Sources

Falk, Rodney, MD, Understanding Amyloidosis. (2018).https://www.youtube.com/watch?v=bE68vvDtnyM&t=134s.

Cleveland Clinic. (2020, June 2). Amyloidosis: AL (Light Chain). https://my.clevelandclinic.org/health/diseases/15718-amyloidosis-al-amyloid-light-chain.

Sherwood, A. L. (n.d.). Understanding Freelite®, the lab test for serum free light chains. Lecture.

The Canadian Amyloidosis Support Network. (n.d.). About Amyloidosis. http://thecasn.org/home-2/what-is-amyloidosis/al-amyloidosys/al-amyloidosis-symptoms/.

Mayo Clinic. 2021. Amyloidosis – Symptoms and causes. [online] Available at: <https://www.mayoclinic.org/diseases-conditions/amyloidosis/symptoms-causes/syc-20353178> [Accessed 14 July 2021].

Amyloidosis Foundation. 2021. AL – Amyloidosis Foundation. [online] Available at: <https://amyloidosis.org/facts/al/#diagnosis> [Accessed 14 July 2021].

AN UPDATE ….. WOO HOO!!!

Well, the results of the preclinical studies were presented on June 26, 2021 and it is fantastic news for hereditary ATTR amyloidosis patients!!!

Preclinical studies showed durable knockout of TTR after a single dose. Serial assessments of safety during the first 28 days after infusion in patients revealed few adverse events, and those that did occur were mild in grade. Dose-dependent pharmacodynamic effects were observed. At day 28, the mean reduction from baseline in serum TTR protein concentration was 52% (range, 47 to 56) in the group that received a dose of 0.1 mg per kilogram and was 87% (range, 80 to 96) in the group that received a dose of 0.3 mg per kilogram.

CONCLUSIONS
In a small group of patients with hereditary ATTR amyloidosis with polyneuropathy, administration of NTLA-2001 was associated with only mild adverse events and led to decreases in serum TTR protein concentrations through targeted knockout of TTR. (Funded by Intellia Therapeutics and Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT04601051. opens in new tab.)

The New England Journal of Medicine
https://www.nejm.org/doi/full/10.1056/NEJMoa2107454

Our original blog post ….

The scientific world is abuzz … a Nobel Prize-winning technology called CRISPR/Cas9 can now edit our DNA. This programmable gene-editing technology, which is efficient, precise, and scalable, has inspired a gold rush of countless applications in medicine, agriculture and basic science. Early areas of focus include genetic diseases such as sickle cell and hereditary ATTR amyloidosis, offering new and exciting optimism.

Ground-Breaking Science in Gene Editing

“A genome is an organism’s complete set of DNA, including all of its genes. Each genome contains all of the information needed to build and maintain that organism. In humans, a copy of the entire genome – more than three billion DNA base pairs – is contained in all cells that have a nucleus.” – Intellia Therapeutics

CRISPR, short for Clustered Regularly Interspaced Short Palindromic Repeats, is a microbial ‘immune system’ that prokaryotes — bacteria and archaea — use to prevent infection by viruses called phages. At its core, the CRISPR system gives prokaryotes the ability to recognize precise genetic sequences that match a phage or other invaders and target these sequences for destruction using specialized enzymes.

Previous work had identified these enzymes, known as CRISPR-associated proteins (Cas), including one called Cas9. But scientist Emmanuelle Charpentier, working first at the University of Vienna and later at the Umeå Centre for Microbial Research in Sweden, identified another key component of the CRISPR system, an RNA molecule that is involved in recognizing phage sequences, in the bacterium Streptococcus pyogenes, which can cause disease in humans.

Charpentier reported the discovery in 2011 and that year struck up a collaboration with American biochemist Jennifer Doudna. In a landmark 2012 paper in Science, the duo isolated the components of the CRISPR–Cas9 system, adapted them to function in the test tube and showed that the system could be programmed to cut specific sites in isolated DNA – an incredibly precise set of DNA-editing genetic scissors. In 2020, Doudna and Charpentier won the 2020 Nobel Prize in Chemistry for their gene-editing technology.

“The ability to cut DNA where you want has revolutionized the life sciences,” said Pernilla Wittung Stafshede, a biophysical chemist and member of the Nobel chemistry committee, at the prize announcement. “The ‘genetic scissors’ were discovered just eight years ago, but have already benefitted humankind greatly.”

How Does CRISPR/Cas9 Work? (3)

This technology acts as an incredibly precise set of molecular scissors, providing instructions to cut an identified gene in a specific position in the nucleus of DNA. There are two primary components to the CRISPR/Cas9 genome editing system:

The Cas9 protein, which initially recognizes the DNA and also acts like a pair of “molecular scissors” that precisely cleaves the targeted DNA sequence.
The guide RNA, which guides the Cas9 scissors to the desired target DNA sequence and activates the scissors so they cut.

https://www.intelliatx.com/crisprcas9/how-crisprcas9-works/

Background on Hereditary Transthyretin Amyloidosis (hATTR/ATTRv) (1)

Transthyretin amyloidosis is a slowly progressive condition characterized by the buildup of abnormal deposits of a protein called amyloid (amyloidosis) in the body’s organs and tissues. These protein deposits most frequently occur in the peripheral nervous system, which is made up of nerves connecting the brain and spinal cord to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound. Protein deposits in these nerves result in a loss of sensation in the extremities (peripheral neuropathy). The autonomic nervous system, which controls involuntary body functions such as blood pressure, heart rate, and digestion, may also be affected by amyloidosis. In some cases, the brain and spinal cord (central nervous system) are affected. Other areas of amyloidosis include the heart, kidneys, eyes, and gastrointestinal tract. The age at which symptoms begin to develop varies widely among individuals with this condition, and is typically between ages 20 and 70.

There are three major forms of transthyretin amyloidosis, which are distinguished by their symptoms and the body systems they affect.

The neuropathic form of transthyretin amyloidosis primarily affects the peripheral and autonomic nervous systems, resulting in peripheral neuropathy and difficulty controlling bodily functions.
The leptomeningeal form of transthyretin amyloidosis primarily affects the central nervous system.
The cardiac form of transthyretin amyloidosis affects the heart.

Mutations in the TTR gene causes the liver to product the TTR protein in a misfolded form. This misfolded protein can then build up in the body and lead to disease-causing nerve and other organ damage.

Clinical Trial Research (4)

According to CRISPRMedicineNews, one of the early clinical trials within gene editing is focused on hereditary transthyretin amyloidosis. In these trials, CRISPR-Cas is either used directly to treat the condition by editing an individual’s genome in vivo or indirectly through ex vivo engineering of a cell-based therapy. An update published November 17, 2020 discusses the clinical trial, which is now underway in the U.K.

CRISPR-Cas9 Trial For NTLA-2001 to Treat Hereditary Transthyretin Amyloidosis With Polyneuropathy

The second newly-added trial is sponsored by US-based Intellia Therapeutics and seeks to enroll 38 participants who are diagnosed with polyneuropathy (PN) due to transthyretin (TTR) amyloidosis (ATTR).

This open-label Phase 1 two-part trial comprises a dose escalation followed by a safety dose expansion study to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of Intellia’s most advanced in vivo CRISPR-based therapy candidate, NTLA-2001.

ATTR is a hereditary progressive condition that is characterized by an accumulation of misfolded transthyretin (TTR) protein. The disease results from mutation(s) in the TTR gene, leading to mutant TRR protein that is unstable and easily forms aggregates that deposit as amyloid in various organs and tissues in the body. Organs or body parts most often affected include the nerves, heart, kidneys and eyes.

Life expectancy is typically 2-15 years from disease onset, and current treatment options include transplantation of affected organs and medications to slow progression of disease symptoms.

NTLA-2001 is the first investigative CRISPR-based therapy to be administered in vivo in humans. The new therapy comprises TTR-targeting gRNA and Cas9 mRNA, both of which are delivered in vivo via Intellia’s proprietary lipid nanoparticle technology. Pre-clinical studies support the notion that NTLA-2001 has potential as a one-time curative treatment. The first patient was dosed with NTLA-2001 last week and the study is expected to be completed in 2024.

Worldwide prevalence of spontaneous and hereditary transthyretin amyloidosis (ATTR). Source: Intellia Therapeutics. https://www.intelliatx.com/in-vivo-therapies/

Potential Game-Changer for Hereditary ATTR Amyloidosis

“Once we’ve assessed safety and established an optimal dose, we intend to rapidly initiate trials for the clinical manifestations of ATTR. NTLA-2001 may halt and reverse ATTR progression by producing a deeper, permanent TTR protein reduction for all patients – regardless of disease type – than the chronically administered treatments currently available.” said Intellia Therapeutics President and CEO, John Leonard, M.D.

Intellia’s proprietary CRISPR/Cas9 system could potentially address diseases with a single course of treatment because it permanently repairs the defective DNA. This represents a breakthrough improvement over current therapies, most of which require lifelong administration because they cannot correct underlying causes of the disease. However, this technology does not pass the genetic changes made to the patient to his or her offspring … the “fix” will not pass from generation to generation.

This is exciting news, giving new hope for families who have been ravaged by disease over generations.

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If you’d like to read more about Jennifer Doudna, here’s a book recently released by bestselling author Walter Isaacson, The Code Breaker.

Sources:

https://crisprmedicinenews.com/clinical-trial/transthyretin-amyloidosis-attr-nct04601051/
crisprmedicinenews.com
https://www.intelliatx.com
https://crisprmedicinenews.com/news/crispr-cas-clinical-trial-update/
https://www.nature.com/articles/d41586-020-02765-9
Doudna Lab, Berkeley, California
CRISPR Therapeutics, Cambridge, Massachusetts
Innovative Genomics Institute, Berkeley, California

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Hereditary Amyloidosis: The T60A Variant

Worldwide Hotspots of Hereditary ATTR Amyloidosis (ATTRv)

WHAT IS TRANSTHYRETIN (TTR)