FAM200B
Chr 4family with sequence similarity 200 member B
Also known as: C4orf53
The FAM200B protein function is not well characterized, but mutations cause autosomal recessive neurodevelopmental disorder with seizures, spastic quadriplegia, and brain malformations including delayed myelination and corpus callosum abnormalities. The gene shows moderate constraint against loss-of-function variants, and affected individuals typically present in infancy with severe developmental delays and neurological impairment.
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Highly tolerant — LoF variants common in population
Mild missense constraint
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.
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.
ClinVar Variant Classifications
72 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories· variant type breakdown unavailable
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | — | — | — | — | 49 |
Likely Pathogenic | — | — | — | — | 3 |
VUS | — | — | — | — | 9 |
Likely Benign | — | — | — | — | 0 |
Benign | — | — | — | — | 1 |
| Total | — | 62 | |||
Counts from ClinVar esearch · Updated hourly
View in ClinVar →Protein Context — Lollipop Plot
FAM200B · protein map & ClinVar variants
Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.
3D Protein StructureAlphaFold
External Resources
Links to major genomics databases and tools
Clinical Trials
Active and recruiting trials from ClinicalTrials.gov
No active trials found for this gene.
Search ClinicalTrials.gov →No open access results found
External Resources
Links to major genomics databases and tools