TTC21A
Chr 3ARtetratricopeptide repeat domain 21A
Also known as: IFT139A, SPGF37, STI2, Thm2
This protein is required for intraflagellar transport and sperm flagellar formation during spermatogenesis. Mutations cause spermatogenic failure 37, characterized by male infertility due to defective sperm motility and development. The inheritance pattern is autosomal recessive.
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Typical tolerance to LoF variation
Mild missense constraint
The highest-scoring mechanism for this gene is dominant-negative.
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
282 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | 4 | 1 | 9 | 0 | 14 |
Likely Pathogenic | 3 | 0 | 1 | 0 | 4 |
VUS | 1 | 195 | 1 | 0 | 197 |
Likely Benign | 0 | 11 | 1 | 10 | 22 |
Benign | 0 | 15 | 0 | 6 | 21 |
| Total | 8 | 222 | 12 | 16 | 258 |
LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly
View in ClinVar →Protein Context — Lollipop Plot
TTC21A · 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 →External Resources
Links to major genomics databases and tools