Hereditary Transthyretin-Mediated (hATTR) Amyloidosis

Number: 0939

Policy

Note: REQUIRES PRECERTIFICATION. 

Precertification of patisiran (Onpattro) and inotersen (Tegsedi) are required of all Aetna participating providers and members in applicable plan designs. For precertification of patisiran (Onpattro) or inotersen (Tegsedi), call (866) 752-7021 or fax (866) 267-3277.

Note: Site of Care Utilization Management Policy applies.  For information on site of service for patisiran (Onpattro), see Utilization Management Policy on Site of Care for Specialty Drug Infusions.

  1. Patisiran (Onpattro)

    1. Aetna considers the initiation of patisiran (Onpattro) intravenous infusion medically necessary for the treatment of polyneuropathy caused by hereditary transthyretin-mediated amyloidosis (hATTR), also called transthyretin-type familial amyloid polyneuropathy (ATTR-FAP), when all of the following criteria are met:

      1. The diagnosis is confirmed by detection of a mutation of the TTR gene, and
      2. Member exhibits clinical manifestations of ATTR-FAP (e.g., amyloid deposition in biopsy specimens, TTR protein variants in serum, progressive peripheral sensory-motor polyneuropathy); and
      3. The member is not a liver transplant recipient; and
      4. Patisiran will be prescribed by or in consultation with a neurologist, geneticist, or physician specializing in the treatment of amyloidosis; and 
      5. Patisiran will not be used in combination with inotersen (Tegsedi) or tafamidis (Vyndaqel, Vyndamax).
    2. Aetna considers the continuation of patisiran (Onpattro) medically necessary for the treatment of ATTR-FAP when all of the following criteria are met:

      1. The member has met all initial selection criteria, and
      2. The member has demonstrated a beneficial response to treatment with patisiran therapy compared to baseline (e.g., improvement of neuropathy severity and rate of disease progression as demonstrated by the modified Neuropathy Impairment Scale+7 (mNIS+7) composite score, the Norfolk Quality of Life-Diabetic Neuropathy (QoL-DN) total score, polyneuropathy disability (PND) score, FAP disease stage, manual grip strength).  Documentation from the medical record must be provided.
    3. Aetna considers concurrent use of patisiran (Onpattro) with inotersen (Tegsdei) experimental and investigational because the safety and effectiveness of this combination has not been established.

    4. Aetna considers patisiran (Onpattro) experimental and investigational for all other indications (e.g., sensorimotor or autonomic neuropathy not related to hATTR amyloidosis) because of insufficient evidence in peer-reviewed published literature.

  2. Inotersen (Tegsedi)

    1. Aetna considers the initiation of inotersen (Tegsedi) subcutaneous injection medically necessary for the treatment of polyneuropathy caused by hereditary transthyretin-mediated (hATTR) amyloidosis, also called transthyretin-type familial amyloid polyneuropathy (ATTR-FAP), when all of the following are met:

      1. The diagnosis is confirmed by detection of a mutation of the TTR gene; and
      2. Member exhibits clinical manifestations of ATTR-FAP (e.g., amyloid deposition in biopsy specimens, TTR protein variants in serum, progressive peripheral sensory-motor polyneuropathy); and
      3. The member is not a liver transplant recipient; and
      4. Inotersen will be prescribed by or in consultation with a neurologist, geneticist, or physician specializing in the treatment of amyloidosis; and 
      5. Inotersen will not be used in combination with patisiran (Onpattro) or tafamidis (Vyndaqel, Vyndamax).
    2. Aetna considers continuation of inotersen (Tegsedi) medically necessary for the treatment of ATTR-FAP when all of the following criteria are met: 

      1. The member has met all initial selection criteria; and
      2. The member has demonstrated a beneficial response to treatment with inotersen therapy compared to baseline (e.g., improvement of neuropathy severity and rate of disease progression as demonstrated by the modified Neuropathy Impairment Scale+7 (mNIS+7) composite score, the Norfolk Quality of Life-Diabetic Neuropathy (QoL-DN) total score, polyneuropathy disability (PND) score, FAP disease stage, manual grip strength). Documentation from the medical record must be provided.
    3. Aetna considers inotersen (Tegsedi) experimental and investigational for all other indications (e.g., sensorimotor or autonomic neuropathy not related to hATTR amyloidosis) because of insufficient evidence in peer-reviewed published literature for these indications.

Dosing Recommendations

Onpattro (patisiran)

  • Onpattro (patisiran) is available as a lipid complex injection as 10 mg/5 mL (2 mg/mL) in a single-dose vial, Onpattro is administered via intravenous (IV) infusion
  • Dosing is based on actual body weight

    • For members weighing less than 100 kg, the recommended dosage is 0.3 mg/kg every 3 weeks by intravenous infusion (IV)
    • For members weighing 100 kg or more, the recommended dosage is 30 mg IV once every 3 weeks.

Source: Alnylam Pharmaceuticals, 2019

Tegesdi (inotersen)

  • Tegsedi (inotersen) is available for injection as 284 mg/ 1.5 mL in a single-dose prefilled syringe
  • The recommended dose of Tegsedi is 284 mg injected subcutaneously once weekly. For consistency of dosing, individuals should be instructed to give the injection on the same day every week. Laboratory tests must be measured prior to treatment, continue to be monitored after treatment initiation, and for 8 weeks following discontinuation of treatment, as directed.

Source: Akcea Therapeutics, 2019 

Background

Hereditary transthyretin amyloidosis (hATTR amyloidosis), formerly known as transthyretin-type familial amyloid polyneuropathy (ATTR-FAP) or familial amyloid cardiomyopathy, now identified by the amyloid fibril-forming protein rather than clinical presentation, is a rare, progressive, autosomal dominant disease primarily characterized by adult-onset sensory, motor, and autonomic neuropathy associated with cardiac, gastrointestinal, ocular, and renal symptoms that can be fatal within 2–15 years from onset. There are more than 50,000 people affected worldwide. Hereditary ATTR amyloidosis is caused by mutations in the TTR gene (chromosome 18q11.2–12.1) that results in misfolded TTR proteins that accumulate as amyloid fibrils in the body’s organs and tissues, such as the nerves, heart and gastrointestinal track. Since hATTR amyloidosis involves many systems in the body, it can result in a wide variety of symptoms, including peripheral and autonomic neuropathy. The amyloid buildup most frequently occurs in the peripheral nervous system, which can result in a loss of sensation, pain, or immobility in the arms, legs, hands and feet. hATTR amyloidosis is a physically debilitating disease that can contribute to significant morbidity and a decline in quality of life, negatively affecting activities of daily living. Available treatment options have focused on symptom management; however, a new drug, in a new drug class called small interfering ribonucleic acid (siRNA) treatment, was FDA approved in August 2018 to target the root cause of the symptoms itself (Akcea Therapeutics, 2018; FDA, 2018; Gonzalez‑Duarte, 2019).

Patisiran (Onpattro)

On August 10, 2018, the U.S. Food and Drug Administration (FDA) announced the approval of Onpattro (patisiran) infusion for the treatment of adults with peripheral nerve disease (polyneuropathy) caused by hereditary transthyretin-mediated amyloidosis (hATTR). Onpattro (patisiran), an RNA interference (RNAi) therapeutic, contains a transthyretin-directed small interfering RNA and has been classified by the FDA as an siRNA drug. siRNAs work by silencing a portion of RNA involved in causing the disease. More specifically, patisiran encases the siRNA into a lipid nanoparticle to deliver the drug directly into the liver, in an infusion treatment, to alter or halt the production of disease-causing proteins. Patisiran is designed to interfere with RNA production of an abnormal form of the protein transthyretin (TTR). By preventing the production of TTR, patisiran can help reduce the accumulation of amyloid deposits in peripheral nerves, improving symptoms and helping adults better manage the condition. (Alnylam Pharmaceuticals, 2018; FDA, 2018; Gonzalez-Duarte, 2019).

The FDA granted Onpattro the Fast Track, Priority Review and Breakthrough Therapy designations. Onpattro also received Orphan Drug designation, which provides incentives to assist and encourage the development of drugs for rare diseases.

FDA approval was based on the APOLLO trial (NCT01960348), which was a randomized, double-blind, placebo-controlled, global, phase 3 study that found that Onpattro improved multiple clinical manifestations of hereditary ATTR amyloidosis. The study included a total of 225 adult patients (18 to 85 years of age) with the diagnosis of hATTR amyloidosis and polyneuropathy. Eligibility criteria also included an estimated survival greater than or equal to 2 years, documented TTR mutation, a Neuropathy Impairment Score (NIS) of 5–130, polyneuropathy disability (PND) score ≤IIIb, adequate biochemical liver function, and serum creatinine ≤ 2 x ULN. Patients were excluded if they had a prior liver transplant or planned to undergo liver transplant during the study period, Type 1 diabetes, Type 2 diabetes greater than or equal to 5 years, active hepatitis B or C, HIV infection, and NYHA heart failure classification greater than 2. Selected patients were randomized 2:1 to receive either intravenous patisiran (n=148) 0.3 mg/kg or placebo (n=77) once every 3 weeks for 18 months. The primary endpoint was to determine the efficacy of patisiran (between the patisiran and placebo groups) based on the difference in the change in the modified Neuropathy Impairment Score+7, which assessed motor strength, reflexes, sensation, nerve conduction and postural blood pressure. Secondary objectives were to evaluate the effect of patisiran on Norfolk-Diabetic Neuropathy quality of life questionnaire score, nutritional status (as evaluated by modified body mass index), motor function (as measured by NIS-weakness and timed 10-m walk test), and autonomic symptoms (as measured by the Composite Autonomic Symptom Score-31 questionnaire). The authors found that patients treated with patisiran had a mean 6.0-point decrease (improvement) in the modified Neuropathy Impairment Score compared to a mean 28.0-point increase (worsening) for patients in the placebo group, resulting in a mean 34.0-point difference relative to placebo, after 18 months of treatment. Fifty-six percent of patisiran-treated patients at 18 months of treatment experienced reversal of neuropathy impairment (as assessed by the modified Neuropathy Impairment Score) relative to their own baseline, compared to 4% of patients who received placebo. Patients also had a mean 6.7-point decrease (improvement) in the Norfolk Quality of Life Diabetic Neuropathy score from baseline compared to a mean 14.4-point increase (worsening) for patients in the placebo group, resulting in a mean 21.1-point difference relative to placebo, after 18 months of treatment. Fifty-one percent of patisiran-treated patients experienced improvement in quality of life at 18 months relative to their own baseline, compared to 10 percent of the placebo-treated patients (per Norfolk QOL-DN questionnaire). Furthermore, the patisiran-treated patients experienced significant benefit vs. placebo for all other secondary efficacy endpoints, including measures of activities of daily living, walking ability, nutritional status, and autonomic symptoms over the 18 months of treatment (Adams et al., 2018; Adams et al., 2017; Alnylam, 2018; FDA, 2018).

The most frequently reported adverse reactions (that occurred in at least 10% of Onpattro-treated patients and at least 3% more frequently than on placebo) were upper respiratory tract infections and infusion-related reactions. To reduce the risk of infusion-related reactions, patients received premedications prior to infusion. Per FDA and Prescribing Information (2018), persons may also experience vision problems including dry eyes, blurred vision and eye floaters (vitreous floaters). It is recommended that individuals are referred to an ophthalmologist if ocular symptoms suggestive of vitamin A deficiency occur. Onpattro (patisiran) leads to a decrease in serum vitamin A levels, so it is recommended that patients take a daily Vitamin A supplement at the recommended daily allowance as per physician/ophthalmologist instructions (FDA, 2018). The administration and dosing recommendations are included in the appendix section.

Milani and colleagues (2019) stated that hATTRv (v for variant) is a rare, progressive, fatal multi-systemic disease, autosomal dominantly inherited with heterogeneous clinical phenotype caused by mutations in the TTR gene.  Mutations promoting proteolytic re-modeling and tetramer dissociation result in fragmented and full-length TTR monomers that misfold, aggregate and deposit at multiple sites (mainly nerves and heart) causing peripheral neuropathy and/or cardiomyopathy.  These investigators discussed patisiran, the first FDA-approved RNA interference-based therapeutic agent that suppresses the circulating levels of the amyloidogenic protein TTR both wild-type and mutant.  This compound demonstrated a safe clinical profile in phase-I and -II clinical trials and showed a significant clinical effect in a phase-III (APOLLO) trial in ATTRv patients.  An open-label extension study is still underway but, based on the positive results, the regulatory agencies granted approval for the treatment of ATTRv with polyneuropathy in Stage I and II.  The authors concluded that the patisiran program has demonstrated that substantial TTR concentration reduction was associated with significant and sustained improvement in polyneuropathy scores, QOL profile and several outcome measures that capture the systemic burden of the disease.  The drug has also been reported to be safe in long-term follow-up studies; however its efficacy for ATTR with cardiomyopathy is under investigation.

Inotersen (Tegsedi)

On October 5, 2018, Akcea Therapeutics, Inc, an affiliate of Ionis Pharmaceuticals, Inc, announced the U.S. Food and Drug Administration (FDA) approval of Tegsedi (inotersen), a once-weekly subcutaneous injection, for the treatment of adults with polyneuropathy of hereditary transthyretin-mediated amyloidosis (hATTR).  Tegsedi, a transthyretin-directed antisense oligonucleotide, targets the disease by reducing the production of TTR proteins.

FDA-approval was based on the NEURO-TTR study which showed Tegsedi produced up to a 79% mean decrease from baseline in serum TTR protein regardless of TTR mutation, sex, age, or race (Akcea, 2018). The NEURO-TTR trial was an international, randomized, double-blind, placebo-controlled, 15-month phase 3 trial that comprehensively evaluated the use of inotersen  in a cohort of  172 adults with stage 1 (ambulatory) or stage 2 (ambulatory with assistance) hereditary transthyretin (ATTRm) amyloidosis with symptoms polyneuropathy. Patients were randomly assigned, in a 2:1 ratio, to receive weekly subcutaneous injections of inotersen (300 mg) or placebo. The primary end points were the change in the modified Neuropathy Impairment Score+7 and the change in the score on the patient-reported Norfolk Quality of Life-Diabetic Neuropathy (QOL-DN) questionnaire. A decrease in scores indicated improvement. Both primary efficacy assessments favored inotersen: the difference in the least-squares mean change from baseline to week 66 between the two groups (inotersen minus placebo) was -19.7 points (p<0.001) for the mNIS+7 and -11.7 points (p<0.001) for the Norfolk QOL-DN score. These improvements were independent of disease stage, mutation type, or the presence of cardiomyopathy. There were 5 deaths in the inotersen group and none in the placebo group. The most frequent serious adverse events in the inotersen group were glomerulonephritis (3%) and thrombocytopenia (3%), with one death associated with grade 4 thrombocytopenia. All patients received enhanced monitoring. The authors concluded that inotersen improved the course of neurologic disease and quality of life in patients with hereditary ATTRm amyloidosis. Thrombocytopenia and glomerulonephritis were managed with enhanced monitoring. The trial was funded by Ionis Pharmaceuticals; ClinicalTrials.gov NCT01737398) (Benson et al, 2018).

Study inclusion criteria consisted of a documented transthyretin variant by genotyping and documented amyloid deposit by biopsy (Ionis, 2018b).

Exclusion criteria (Ionis, 2018b) consisted of:

  • Low Retinol level at screen
  • Karnofsky performance status ≤50
  • Poor Renal function
  • Known type 1 or type 2 diabetes mellitus
  • Other causes of sensorimotor or autonomic neuropathy (e.g., autoimmune disease)
  • If previously treated with Vyndaqel, had discontinued treatment for 2 weeks prior to Study Day 1. If previously treated with Diflunisal, had discontinued treatment for 3 days prior to Study Day 1
  • Previous treatment with any oligonucleotide or siRNA within 12 months of screening
  • Prior liver transplant or anticipated liver transplant within 1 year of screening
  • New York Heart Association (NYHA) functional classification of ≥3
  • Acute Coronary Syndrome or major surgery within 3 months of screening
  • Known Primary or Leptomeningeal Amyloidosis
  • Anticipated survival less than 2 years.

The most common adverse reactions ( 20% more frequently than placebo) were injection site reactions, nausea, headache, fatigue, thrombocytopenia, and fever  (Ionis, 2018a).

Because of the risks of serious bleeding caused by severe thrombocytopenia and risk of glomerulonephritis, both of which require frequent monitoring, Tegsedi is only available through a restricted distribution program under a Risk Evaluation and Mitigation Strategy (REMS) called the TEGSEDI REMS Program (Ionis, 2018a). The REMS program requires persons to comply with ongoing monitoring requirements. 

Warnings and precautions per Prescribing Information (Ionis, 2018a) include:

  • Thrombocytopenia: Tegsedi causes reductions in platelet count that may result in sudden and unpredictable thrombocytopenia, which can be life-threatening.
  • Glomerulonephritis: Tegsedi can cause glomerulonephritis that may require immunosuppressive treatment and may result in dialysis-dependent renal failure.
  • In clinical trials, cases of glomerulonephritis were accompanied by nephrotic syndrome, which can have manifestations of edema, hypercoagulability with venous or arterial thrombosis, and increased susceptibility to infection.
  • Stroke and Cervicocephalic Arterial Dissection: These adverse events occurred within 2 days of first dose and with symptoms of cytokine release. Patients should be educated on symptoms of stroke and central nervous system arterial dissection.
  • Inflammatory and Immune Effects: Serious neurologic adverse reactions consistent with inflammatory and immune effects occurred.
  • Liver effects: Monitor alanine amino transferase, aspartate aminotransferase, and total bilirubin every 4 months during treatment and in case of symptoms of hepatic dysfunction.
  • Hypersensitivity reactions: if these occur, discontinue and initiate appropriate therapy.
  • Uninterpretable Platelet Counts: Reaction between Antiplatelet Antibodies and ethylenediaminetetra-acetic acid: Platelet clumping can cause uninterpretable platelet measurement; repeat test if this is suspected
  • Reduced Serum Vitamin A Levels and Recommended Supplementation: Supplement with the recommended daily allowance of vitamin A. Refer to an ophthalmologist if ocular symptoms suggestive of vitamin A deficiency occur.
Inotersen (Tegsdei) should not be used concomitantly with patisiran (Onpattro) because the safety and effectiveness of this combination has not been established.

Appendix

Table: Clinical Staging of TTR-FAP
Stage 0 No symptoms
Stage 1 Unimpaired ambulation; mostly mild sensory, motor, and autonomic neuropathy in the lower limbs.
Stage 2 Assistance with ambulation required; mostly moderate impairment progression to the lower limbs, upper limbs, and trunk.
Stage 3 Wheelchair-bound or bedridden; severe sensory, motor, and autonomic involvement of all limbs

Table based on Coutinho et al. (Ando et al., 2013)

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+" :

Patisiran (Onpattro):

Other CPT codes related to the CPB:

96365 - 96368 Intravenous infusion administration

HCPCS codes covered if selection criteria are met:

J0222 Injection, patisiran, 0.1 mg

ICD-10 codes covered if selection criteria are met:

E85.1 Neuropathic heredofamilial amyloidosis [transthyretin-type familial amyloid polyneuropathy (ATTR-FAP)]

ICD-10 codes not covered for indications listed in the CPB:

T86.4 Complications of liver transplant
Z94.4 Liver transplant status

Inotersen (Tegsedi):

Other CPT codes related to the CPB:

96372 Therapeutic, prophylactic, or diagnostic injection (specify substance or drug); subcutaneous or intramuscular

HCPCS codes covered if selection criteria are met:

Inotersen (Tegsedi) - no specific code:

ICD-10 codes covered if selection criteria are met:

E85.1 Neuropathic heredofamilial amyloidosis [transthyretin-type familial amyloid polyneuropathy (ATTR-FAP)]

ICD-10 codes not covered for indications listed in the CPB:

T86.4 Complications of liver transplant
Z94.4 Liver transplant status

The above policy is based on the following references:

Patisiran (Onpattro)

  1. Akcea Therapeutics, Inc. hATTR amyloidosis. 2018. Available at: https://www.hattrguide.com/about-hattr-amyloidosis/. Accessed August 16, 2018.
  2. Adams D, Gonzalez-Duarte A, O'Riordan WD, et al. Patisiran, an RNAi Therapeutic, for Hereditary Transthyretin Amyloidosis. N Engl J Med. 2018;379(1):11-21.
  3. Adams D, Suhr OB, Dyck PJ, et al. Trial design and rationale for APOLLO, a Phase 3, placebo-controlled study of patisiran in patients with hereditary ATTR amyloidosis with polyneuropathy. BMC Neurology. 2017;17:181.
  4. Alnylam Pharmaceuticals, Inc. Onpattro (patisiran) lipid complex injection, for intravenous use. Prescribing Information. Cambridge, MA: Alynlam Pharmaceuticals; revised August 2018.
  5. Alnylam Pharmaceuticals, Inc. Onpattro (patisiran) lipid complex injection, for intravenous use. Prescribing Information. Cambridge, MA: Alynlam Pharmaceuticals; revised September 2019.
  6. Ando Y, Coelho T, Berk JL, et al. Guideline of transthyretin-related hereditary amyloidosis for clinicians. Orphanet J Rare Dis. 2013; 8:31.
  7. Gonzalez-Duarte A. Autonomic involvement in hereditary transthyretin amyloidosis (hATTR amyloidosis). Clin Auton Res. 2019;29(2):245-251.
  8. Milani P, Mussinelli R, Perlini S, et al. An evaluation of patisiran: A viable treatment option for transthyretin-related hereditary amyloidosis. Expert Opin Pharmacother. 2019 Sep 30 [Epub ahead of print].
  9. Minamisawa M, Claggett B, Adams D, et al. Association of patisiran, an RNA interference therapeutic, with regional left ventricular myocardial strain in hereditary transthyretin amyloidosis: The APOLLO Study. JAMA Cardiol. 2019;4(5):466-472. 
  10. Sekijima Y, Yoshida K, Tokuda T, Ikeda S. Familial transthyretin amyloidosis. In: GeneReviews. Seattle (WA): University of Washington, Seattle. 1993-2017. https://www.ncbi.nlm.nih.gov/books/NBK1194/. Accessed 16 Aug 2018.
  11. U.S Food and Drug Administration (FDA). FDA approves first-of-its kind targeted RNA-based therapy to treat a rare disease. FDA News Release. Silver Spring, MD: FDA; August 10, 2018.
  12. Zhang X, Goel V, Attarwala H, et al. Patisiran pharmacokinetics, pharmacodynamics, and exposure-response analyses in the phase 3 APOLLO Trial in patients with hereditary transthyretin-mediated (hATTR) amyloidosis. J Clin Pharmacol. 2019 Jul 19 [Epub ahead of print].

Inotersen (Tegsedi)

  1. Akcea Therapeutics, Inc. Akcea and Ionis receive FDA approval of Tegsedi (inotersen) for the treatment of the polyneuropathy of hereditary transthyretin-mediated amyloidosis in adults. Press Release. Boston, MA: Akcea; October 5, 2018.
  2. Akcea Therapeutics, Inc. Tegsedi (inotersen) injection, for subcutaneous use. Prescribing Information. Boston, MA: Akcea Therapeutics; revised October 2018.
  3. Akcea Therapeutics, Inc. Tegsedi (inotersen) injection, for subcutaneous use. Prescribing Information. Boston, MA: Akcea Therapeutics; revised October 2019.
  4. Ando Y, Coelho T, Berk JL, et al. Guideline of transthyretin-related hereditary amyloidosis for clinicians. Orphanet J Rare Dis. 2013;8:31.
  5. Benson MD, Waddington-Cruz M, Berk JL, et al. Inotersen treatment for patients with hereditary transthyretin amyloidosis. N Engl J Med. 2018;379(1):22-31.
  6. Gales L. Tegsedi (inotersen): An antisense oligonucleotide approved for the treatment of adult patients with hereditary transthyretin amyloidosis. Pharmaceuticals (Basel). 2019;12(2).
  7. Gertz MA, Scheinberg M, Waddington-Cruz M, et al. Inotersen for the treatment of adults with polyneuropathy caused by hereditary transthyretin-mediated amyloidosis. Expert Rev Clin Pharmacol. 2019;12(8):701-711.
  8. Ionis Pharmaceuticals, Inc. Tegsedi (inotersen) injection, for subcutaneous use. Prescribing Information. Reference ID: 4330796. Carlsbad, CA: Ionis; revised October 2018a.
  9. Ionis Pharmaceuticals, Inc. Efficacy and safety of inotersen in familial amyloid polyneuropathy. ClinicalTrials.gov Identifier: NCT01737398. Bethesda, MD: National Library of Medicine (NLM); updated June 19, 2018. 
  10. National Institutes of Health (NIH), National Library of Medicine (NLM). Transthyretin amyloidosis. Genetics Home Reference. Bethesda, MD: NIH; October 2018. 
  11. Waddington-Cruz M, Ackermann EJ, Polydefkis M, et al. Hereditary transthyretin amyloidosis: Baseline characteristics of patients in the NEURO-TTR trial. Amyloid. 2018;25(3):180-188.