Genetic analyses and expression studies identified a novel mutation (W486C) as a molecular basis of congenital coagulation factor XII deficiency.
We analyzed the factor XII (FXII) gene of a patient with congenital FXII deficiency and identified a novel amino acid substitution (W486C) in the catalytic domain. The proband was an asymptomatic 49-year-old Japanese female with abnormal coagulation test, discovered by chance. The FXII activity and antigen level were both under 10%, suggesting a cross-reacting material-negative FXII deficiency. Sequence analysis of the proband's FXII gene revealed a homozygous nucleotide substitution G --> C in exon 12, resulting in the amino acid substitution W486C in the catalytic domain. We constructed the mutant FXII cDNA in an expression plasmid vector and transfected it into Chinese hamster ovary cells. The recombinant wild-type FXII antigen was detected in the culture medium by immunoprecipitation assay, but the mutant FXII (W486C) was not observed. On the other hand, both the wild-type FXII and W486C cell lysates contained FXII antigen and FXII mRNA, as estimated by western blotting and quantitative reverse transcriptase-polymerase chain reaction. These findings suggest that the W486C substitution of FXII impairs intracellular processing of the protein and/or transport system.
Ishii
Keiko
K
Department of Laboratory Medicine, Division of Hematology, School of Medicine, Keio University, Tokyo, Japan.
Oguchi
Shuji
S
Moriki
Takanori
T
Yatabe
Yoko
Y
Takeshita
Eiko
E
Murata
Mitsuru
M
Ikeda
Yasuo
Y
Watanabe
Kiyoaki
K
D019943:Amino Acid Substitution / Q000235:genetics*; D001483:Base Sequence; D002648:Child; D005091:Exons / Q000235:genetics*; D005174:Factor XII / Q000235:genetics* / Q000378:metabolism; D005175:Factor XII Deficiency / Q000235:genetics*; D005260:Female; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D017354:Point Mutation; D011499:Protein Processing, Post-Translational / Q000235:genetics; D021381:Protein Transport / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
D011994:Recombinant Proteins; D005174:Factor XII