Kininogens are multifunctional plasma glycoproteins. There are two forms of
human kininogen: low molecular weight kininogen (LK) and high molecular we
ight kininogen (HK). Both are derived from the same gene by alternative spl
icing. Same patients with kininogen deficiency have been reported to be def
icient only in HK while others are deficient in both HK and LK (total kinin
ogen deficiency). We analyzed three Japanese patients with total kininogen
deficiency by the Csp45I digestion study of exon 5 as previously reported i
n Williams trait and found that two had the same point mutation of C to T a
t base 22 of exon 5, resulting in a transition of CGA (Arg) codon to TGA (S
top) codon. This is the first report of molecular characterization of total
kininogen deficiency in the Japanese population. (C) 1999 The Japanese Soc
iety of Hematology.