STAC3

Chr 12AR

SH3 and cysteine rich domain 3

Also known as: CMYO13, CMYP13, MYPBB, NAM

NCBI Gene: 246329 ENSG00000185482 UniProt: Q96MF2

The protein encoded by this gene is a component of the excitation-contraction coupling machinery of muscles. This protein is a member of the Stac gene family and contains an N-terminal cysteine-rich domain and two SH3 domains. Mutations in this gene are a cause of Native American myopathy. [provided by RefSeq, Nov 2013]

Primary Disease Associations & Inheritance

Congenital myopathy 13MIM #255995

Active trials

Pathogenic / LP

200

ClinVar variants

Pubs (1 yr)

0.9

Missense Z

0.75

LOEUF

Clinical Summary— STAC3

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Gene-Disease Validity (ClinGen)

Bailey-Bloch congenital myopathy · ARDefinitive

Definitive — sufficient evidence for diagnostic panels

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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

12 Pathogenic / Likely Pathogenic· 98 VUS of 200 total submissions

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GeneReview available — STAC3

Authoritative clinical overview · Recommended first read

Open GeneReview ↗

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.

0.75LOEUF

pLI 0.000

Z-score 2.44

OE 0.44 (0.27–0.75)

Tolerant

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.

0.91Z-score

OE missense 0.83 (0.73–0.94)

180 obs / 217.6 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.0.44 (0.27–0.75)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.83 (0.73–0.94)

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.0.82

0≤1.21.6

LoF obs/exp: 10 / 22.5Missense obs/exp: 180 / 217.6Syn Z: 1.26

0.6260th %ile

GOF

0.6639th %ile

LOF

0.4332th %ile

This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function, dominant-negative and loss-of-function). 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

LOF50% of P/LP variants are LoF

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. Mechanism ranking also informed by gnomAD constraint, ClinVar, and ClinGen data.