TTR

Chr 18AD

transthyretin

Also known as: AMYLD1, ATTR, CTS, CTS1, HEL111, HsT2651, PALB, TBPA

This gene encodes one of the three prealbumins, which include alpha-1-antitrypsin, transthyretin and orosomucoid. The encoded protein, transthyretin, is a homo-tetrameric carrier protein, which transports thyroid hormones in the plasma and cerebrospinal fluid. It is also involved in the transport of retinol (vitamin A) in the plasma by associating with retinol-binding protein. The protein may also be involved in other intracellular processes including proteolysis, nerve regeneration, autophagy and glucose homeostasis. Mutations in this gene are associated with amyloid deposition, predominantly affecting peripheral nerves or the heart, while a small percentage of the gene mutations are non-amyloidogenic. The mutations are implicated in the etiology of several diseases, including amyloidotic polyneuropathy, euthyroid hyperthyroxinaemia, amyloidotic vitreous opacities, cardiomyopathy, oculoleptomeningeal amyloidosis, meningocerebrovascular amyloidosis and carpal tunnel syndrome. [provided by RefSeq, Aug 2017]

Primary Disease Associations & Inheritance

[Dystransthyretinemic hyperthyroxinemia]MIM #145680
AD
Amyloidosis, hereditary systemic 1MIM #105210
AD
Carpal tunnel syndrome, familialMIM #115430
AD
UniProtHyperthyroxinemia, dystransthyretinemic
490
ClinVar variants
170
Pathogenic / LP
0.52
pLI score
12
Active trials
Clinical SummaryTTR
🧬
Gene-Disease Validity (ClinGen)
obsolete hereditary ATTR amyloidosis · ADDefinitive

Definitive — sufficient evidence for diagnostic panels

Population Constraint (gnomAD)
Moderately constrained gene (pLI 0.52) — some intolerance to loss-of-function variants.
📋
ClinVar Variants
170 Pathogenic / Likely Pathogenic· 151 VUS of 490 total submissions
💊
Clinical Trials
12 active or recruiting trials — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Moderate LoF intolerance
LoF Constraint?LOEUF (Loss-of-function Observed/Expected Upper bound Fraction) is the upper bound of the 90% CI for LoF OE — the preferred gnomAD v4 metric. Lower = more intolerant to LoF. LOEUF < 0.35 = highly constrained.
0.76LOEUF
pLI 0.516
Z-score 1.94
OE 0.16 (0.060.76)
Moderately constrained

Typical tolerance to LoF variation

Missense Constraint?Missense Z-score: standard deviations fewer missense variants observed vs. expected. Z > 3.09 (p < 0.001) = gene does not tolerate missense variation. OE missense < 0.6 is also considered constrained.
1.01Z-score
OE missense 0.69 (0.550.86)
57 obs / 83.0 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?Shaded band = 90% confidence interval. Vertical tick = point estimate. Grey threshold line = gnomAD constraint cutoff for that variant class.
LoF OE?Ratio of observed to expected LoF variants. Upper CI bound (LOEUF) ≤ 0.35 = strong LoF constraint signal.0.16 (0.060.76)
00.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.69 (0.550.86)
00.61.4
Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.0.90
01.21.6
LoF obs/exp: 1 / 6.2Missense obs/exp: 57 / 83.0Syn Z: 0.43

ClinVar Variant Classifications

490 submitted variants in ClinVar

Classification Summary

Pathogenic94
Likely Pathogenic76
VUS151
Likely Benign115
Benign12
Conflicting42
94
Pathogenic
76
Likely Pathogenic
151
VUS
115
Likely Benign
12
Benign
42
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
56
38
0
94
Likely Pathogenic
0
75
1
0
76
VUS
15
88
46
2
151
Likely Benign
0
3
48
64
115
Benign
0
0
11
1
12
Conflicting
42
Total1522214467490

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

Protein Context — Lollipop Plot

TTR · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Gene2Phenotype Curations

TTR-related hereditary transthyretin (ATTR) amyloidosis

definitive
ADGain Of FunctionAltered Gene Product Structure
Cardiac
G2P ↗
missense variantinframe deletioninframe insertion

Gene2Phenotype curations · DECIPHER consortium patient cohort (public variants) · deciphergenomics.org

OMIM — Genotype-Phenotype Relationships

1 OMIM entry

TRANSTHYRETIN; TTR
MIM #176300 · *

[Dystransthyretinemic hyperthyroxinemia]

MIM #145680

Molecular basis of disorder known

Autosomal dominant

Amyloidosis, hereditary systemic 1

MIM #105210

Molecular basis of disorder known

Autosomal dominant

Carpal tunnel syndrome, familial

MIM #115430

Molecular basis of disorder known

Autosomal dominant
📖
GeneReview available — TTR
Authoritative clinical overview · NCBI Bookshelf · Recommended first read
Open GeneReview ↗
Clinical Literature
Landmark / reviewRecent case evidence

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

Solid Tumor

HS-IT101 Injection in the Treatment of Advanced Solid Tumors

RECRUITING
NCT06342336Phase PHASE1Qingdao Sino-Cell Biomedicine Co., Ltd.Started 2024-01-18
HS-IT101 Injection
High-grade GliomaWHO Grade Ⅳ Glioma

Safety and Efficacy Study of TX103 CAR-T Cell Therapy for Recurrent or Progressive Grade 4 Glioma.

RECRUITING
NCT06482905Phase PHASE1Tcelltech Inc.Started 2024-09-04
Anti-B7-H3 Chimeric Antigen Receptor T-Cell (CAR-T Cell) Injection/TX103
CTCL

A Phase 2 Study of PTX 100 in Patients With Relapsed/Refractory CTCL

RECRUITING
NCT06854653Phase PHASE2Prescient Therapeutics, Ltd.Started 2025-03-28
PTX-100
Advanced Breast CancerER-positive Breast CancerHER2-negative Breast Cancer

Elacestrant + Everolimus in Patients ER+/HER2-, ESR1mut, Advanced Breast Cancer Progressing to ET and CDK4/6i.

ACTIVE NOT RECRUITING
NCT06382948Phase PHASE3MedSIRStarted 2024-12-05
EverolimusElacestrantPlacebo
Solid Tumor

A Study to Evaluate the Efficacy and Safety of TL118 in Solid Tumors Patients

RECRUITING
NCT06010342Phase PHASE2Teligene USStarted 2023-03-16
TL118 Capsule
Duchenne Muscular Dystrophy (DMD)Becker's Muscular Dystrophy (BMD)

Urinary Titin Biomarker in DMD

RECRUITING
NCT07332013Phase NAChildren's Hospital of PhiladelphiaStarted 2026-03-01
Descending stair walk
Advanced Breast CancerAdvanced Breast CarcinomaHormone Receptor Positive Breast Carcinoma

Safety and Efficacy of T-DXd vs. CDK4/6i-based ET as First-line Therapy of HR-positive and HER2-low/Ultralow Advanced Breast Cancer Patients Classified as Non-luminal Subtype

RECRUITING
NCT06486883Phase PHASE2MedSIRStarted 2025-06-30
Trastuzumab deruxtecan (T-DXd, DS-8201a)CDK4/6i plus ET
Neoplasms

Master Protocol to Assess the Safety and Antitumor Activity of Genetically Engineered T Cells in NY-ESO-1 and/or LAGE-1a Positive Solid Tumors

ACTIVE NOT RECRUITING
NCT03967223Phase PHASE2USWM CT, LLCStarted 2019-12-31
Letetresgene autoleucel (lete-cel, GSK3377794)FludarabineCyclophosphamide
Recurrent Chronic Lymphocytic Leukemia/Small Lymphocytic LymphomaRefractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Nemtabrutinib and Lisocabtagene Maraleucel for the Treatment of Relapsed/Refractory Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

NOT YET RECRUITING
NCT07194980Phase PHASE2Fred Hutchinson Cancer CenterStarted 2026-04-01
NemtabrutinibLisocabtagene Maraleucel
CNS TumorSolid Tumor

INFORM2 Study Uses Nivolumab and Entinostat in Children and Adolescents With High-risk Refractory Malignancies

RECRUITING
NCT03838042Phase PHASE1, PHASE2University Hospital HeidelbergStarted 2020-05-26
Nivolumab and Entinostat
Relapsed/Refractory Multiple MyelomaPlasma Cell Leukemia

A Study of CAR-GPRC5D in Patients With Relapsed/Refractory Multiple Myeloma or Plasma Cell Leukemia

RECRUITING
NCT05219721Phase PHASE1Chunrui LiStarted 2022-03-17
CAR-T (CAR-GPRC5D)
Amyloidosis, HereditaryAmyloidosis CardiacAmyloidosis, Familial

Subclinical Transthyretin Cardiac Amyloidosis in V122I TTR Carriers

RECRUITING
NCT05489549University of Texas Southwestern Medical CenterStarted 2022-11-21