GPATCH1 (G-patch domain containing 1) is a conserved spliceosomal protein that functions as a splicing fidelity factor. It localizes to the nucleus and nucleoplasm where it participates in catalytic step 2 of the spliceosome 1. GPATCH1 functions as part of a conserved G-patch/helicase pair with DHX35 (human homolog of yeast Gih35), working together to promote splicing accuracy and suppress cryptic splice site usage 2. Structurally, GPATCH1 recognizes remodeled spliceosomal active sites and helps maintain catalytic dormancy during quality control surveillance 1. The protein interacts with host splicing machinery and can be competitively bound by viral factors; HTLV-1 Tax protein inhibits HBZ gene splicing by competing for GPATCH1 binding 3. Clinically, GPATCH1 variants are associated with multiple disease phenotypes. Genome-wide association studies identified GPATCH1 as a novel candidate gene for congenital heart disease (CHD), with mutations enriched in CHD patients 4. Additionally, SNPs in GPATCH1 (rs10416265) show significant associations with osteoporosis susceptibility and fracture risk in multiple populations 5 6. GPATCH1 appears to function as a tissue-specific splicing factor 7, suggesting its effects on bone metabolism and cardiac development may involve splicing regulation of lineage-specific genes.