TBXA2R

Chr 19AD

thromboxane A2 receptor

Also known as: BDPLT13, TXA2-R

NCBI Gene: 6915 ENSG00000006638 UniProt: P21731

This gene encodes a member of the G protein-coupled receptor family. The protein interacts with thromboxane A2 to induce platelet aggregation and regulate hemostasis. A mutation in this gene results in a bleeding disorder. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2009]

Primary Disease Associations & Inheritance

{Bleeding disorder, platelet-type, 13, susceptibility to}MIM #614009

Active trials

Pathogenic / LP

277

ClinVar variants

Pubs (1 yr)

1.1

Missense Z

1.36

LOEUF

Clinical Summary— TBXA2R

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Gene-Disease Validity (ClinGen)

qualitative platelet defect · ADModerate

Moderate evidence — consider for supplementary testing

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Population Constraint (gnomAD)

Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.

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ClinVar Variants

23 Pathogenic / Likely Pathogenic· 155 VUS of 277 total submissions

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Tolerant — LoF & missense variants common in population

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.

1.36LOEUF

pLI 0.000

Z-score 0.78

OE 0.73 (0.41–1.36)

Tolerant

Highly tolerant — LoF variants common in population

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.

1.07Z-score

OE missense 0.82 (0.74–0.92)

239 obs / 290.4 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.0.73 (0.41–1.36)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.82 (0.74–0.92)

0≤0.61.4

Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.1.05

0≤1.21.6

LoF obs/exp: 7 / 9.6Missense obs/exp: 239 / 290.4Syn Z: -0.43

0.74top 25%

GOF

0.82top 10%

LOF

0.2580th %ile

This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function and dominant-negative). Both the Badonyi & Marsh prediction and the broader genomic evidence point to gain-of-function as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

GOFprediction above median

DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.