Identification of an inframe deletion and a missense mutation in the factor XIIIA gene in two Turkish patients.

We report two novel mutations in factor XIIIA (FXIIIA) gene that caused congenital factor XIII deficiency in two unrelated patients. The first alteration, a missense mutation Leu235Arg in exon 6 of FXIIIA gene, is located in the putative calcium-binding part of the core domain of the enzyme. Replacement of non-polar hydrophobic leucine residue with positively charged arginine residue is likely to effect protein folding thus destabilizing the molecule. The second mutation is a 3-bp deletion in exon 14 of FXIIIA gene. This deletion is located in beta barrel 2 domain of the protein and results in translation of an aberrant FXIIIA molecule that lacks lysine residue either at positions 677 or 678. As this inframe deletion is located in a direct repetetive sequence of AAGAAG, that codes for two lysine residues, the exact location of deletion could not be detected.