KRT33A

Chr 17

keratin 33A

Also known as: HA3I, Ha-3I, K33A, KRTHA3A, Krt1-3, hHa3-I

NCBI Gene: 3883 ENSG00000006059 UniProt: O76009

This gene encodes a member of the keratin gene family. This gene is one of multiple type I hair keratin genes that are clustered in a region of chromosome 17q12-q21 and have the same direction of transcription. As a type I hair keratin, the encoded protein is an acidic protein which heterodimerizes with type II keratins to form hair and nails. There are two isoforms of this protein, encoded by two separate genes, keratin 33A and keratin 33B. [provided by RefSeq, May 2012]

Active trials

Pathogenic / LP

113

ClinVar variants

Pubs (1 yr)

-1.0

Missense Z

1.69

LOEUF

Clinical Summary— KRT33A

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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

7 Pathogenic / Likely Pathogenic· 102 VUS of 113 total submissions

Some data sources returned errors (1)

pubtator: TypeError: fetch failed

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.

1.69LOEUF

pLI 0.000

Z-score -0.82

OE 1.20 (0.86–1.69)

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.

-1.02Z-score

OE missense 1.18 (1.07–1.30)

294 obs / 248.7 exp

Tolerant

Tolerant to missense variation

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.1.20 (0.86–1.69)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.1.18 (1.07–1.30)

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: 23 / 19.1Missense obs/exp: 294 / 248.7Syn Z: -0.41

0.92top 5%

GOF

0.89top 5%

LOF

0.2189th %ile

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

DNprediction above median

GOFprediction 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.