Two novel factor X gene mutations in a Chinese family with factor X deficiency

We report a factor X (FX)-deficient Chinese family with two novel FX gene (F10) mutations. Two sibling probands had a bleeding tendency since childhood. Both had very low FX:C (<0.01 IU/ml) and FX:Ag (5-6%) levels and were heterozygous for two novel F10 mutations, a 2-bp GC deletion involving nucleotides 33 and 34, leading to premature chain termination at residue 45, and a T237-->C mutation, leading to Phe71-->Ser. A family study confirmed that the mother had the 2-bp GC deletion and a type I FX deficiency. The father had the Phe71-->Ser mutation. Interestingly, a type I FX deficiency was also observed, suggesting that Phe71-->Ser, occurring at a site sandwiched between two Gla residues, might perturb FX protein stability.