SPAG1
Chr 8ARsperm associated antigen 1
Also known as: CILD28, CT140, DNAAF13, HEL-S-268, HSD-3.8, SP75, TPIS
SPAG1 encodes a GTPase that binds GTP and is involved in cytoplasmic assembly of ciliary dynein arms, with additional roles in spermatogenesis and fertilization. Mutations cause primary ciliary dyskinesia type 28, inherited in an autosomal recessive pattern. The gene shows very low constraint against loss-of-function variants (pLI near zero), consistent with the recessive inheritance pattern where heterozygous carriers are typically unaffected.
Definitive — sufficient evidence for diagnostic panels
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Typical tolerance to LoF variation
Mild missense constraint
Predictions shown for reference only — model trained on dominant genes, not applicable to AR conditions.
The Badonyi & Marsh prediction model was trained exclusively on dominant disease genes. Predictions are not reliable for genes with autosomal recessive inheritance and are shown at reduced opacity for reference only.
Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.
ClinVar Variant Classifications
0 submitted variants in ClinVar
Protein Context — Lollipop Plot
SPAG1 · 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