MAP3K3

Chr 17Somatic

mitogen-activated protein kinase kinase kinase 3

Also known as: CCM5, MAPKKK3, MEKK3

NCBI Gene: 4215 ENSG00000198909 UniProt: Q99759

This gene product is a 626-amino acid polypeptide that is 96.5% identical to mouse Mekk3. Its catalytic domain is closely related to those of several other kinases, including mouse Mekk2, tobacco NPK, and yeast Ste11. Northern blot analysis revealed a 4.6-kb transcript that appears to be ubiquitously expressed. This protein directly regulates the stress-activated protein kinase (SAPK) and extracellular signal-regulated protein kinase (ERK) pathways by activating SEK and MEK1/2 respectively; it does not regulate the p38 pathway. In cotransfection assays, it enhanced transcription from a nuclear factor kappa-B (NFKB)-dependent reporter gene, consistent with a role in the SAPK pathway. Alternatively spliced transcript variants encoding distinct isoforms have been observed. [provided by RefSeq, Jul 2008]

Primary Disease Associations & Inheritance

Cerebral cavernous malformations 5MIM #621032

Somatic

Active trials

Pathogenic / LP

124

ClinVar variants

Pubs (1 yr)

2.0

Missense Z

0.30

LOEUF· LoF intolerant

Clinical Summary— MAP3K3

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Population Constraint (gnomAD)

Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 0.99). One damaged copy is likely sufficient to cause disease.

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ClinVar Variants

11 Pathogenic / Likely Pathogenic· 91 VUS of 124 total submissions

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Clinical Trials

1 active or recruiting trial — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

LoF intolerant — likely haploinsufficient

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.

0.30LOEUF

pLI 0.985

Z-score 4.92

OE 0.15 (0.08–0.30)

Highly constrained

Highly LoF-intolerant (top ~10% of genes)

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.

2.04Z-score

OE missense 0.72 (0.65–0.79)

293 obs / 409.2 exp

Mild constraint

Moderately missense-constrained (top ~2.5%)

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.0.15 (0.08–0.30)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.72 (0.65–0.79)

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.0.92

0≤1.21.6

LoF obs/exp: 6 / 39.3Missense obs/exp: 293 / 409.2Syn Z: 0.80

0.5279th %ile

GOF

0.5071th %ile

LOF

0.67top 25%

The highest-scoring mechanism for this gene is loss-of-function (haploinsufficiency).

LOFprediction above median · LOEUF 0.30

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312. Mechanism ranking also informed by gnomAD constraint, ClinVar, and ClinGen data.