Molecular characterization of total kininogen deficiency in Japanese patients

Kininogens are multifunctional plasma glycoproteins. There are two forms of human kininogen: low molecular weight kininogen (LK) and high molecular weight kininogen (HK). Both are derived from the same gene by alternative splicing. Some patients with kininogen deficiency have been reported to be deficient only in HK while others are deficient in both HK and LK (total kininogen deficiency). We analyzed three Japanese patients with total kininogen deficiency by the Csp45I digestion study of exon 5 as previously reported in Williams trait and found that two had the same point mutation of C to T at base 22 of exon 5, resulting in a transition of CGA (Arg) codon to TGA (Stop) codon. This is the first report of molecular characterization of total kininogen deficiency in the Japanese population.