Molecular abnormality observed in a patient with coagulation factor X (FX) deficiency: a novel three-base-pair (CTT) deletion within the polypyrimidine tract of the FX intron D

We investigated the molecular defect underlying congenital factor X (FX) deficiency in a Japanese patient, A novel three-base-pair deletion was identified within intron D of the FX gene, An allele-specific restriction analysis showed the propositus was homozygous and her two daughters were heterozygous for the deletion, It was not detected in 53 unrelated Japanese (106 alleles) indicating a probable cause of the FX deficiency The deletion resides within a polypyrimidine tract of the acceptor splicing site where U2 snRNP binds to form spliceosomes. The defect could alter the formation of spliceosomes, resulting in incorrect splicing and decreased FX production.