Factor XII Shizuoka, a novel mutation (Ala392Thr) identified and characterized in a patient with congenital coagulation factor XII deficiency.
We identified a novel mutation (Ala392Thr) in the factor XII (FXII) gene of a patient with congenital FXII deficiency, designated Factor XII Shizuoka. The proband was an asymptomatic 63-year-old Japanese male with an abnormal coagulation test, discovered by chance during preoperative testing. The FXII activity was under 3% and antigen level was under 10%. Sequence analysis of the proband's FXII gene revealed a homozygous nucleotide substitution G to A in exon 10, resulting in the amino acid substitution Ala392 to Thr in the catalytic domain. We constructed the mutant FXII cDNA in an expression plasmid vector and transfected it into Chinese hamster ovary (CHO) cells. The recombinant wild-type FXII antigen was detected in the culture medium by immunoprecipitation assay, but the mutant FXII (A392T) was not observed. Both the wild-type FXII and A392T cell lysates, however, contained equivalent levels of FXII antigen and FXII mRNA, as estimated by Western blotting and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), respectively. These findings suggest that the Ala392 to Thr substitution impairs intracellular protein processing and causes a cross-reacting material -negative FXII deficiency.
Oguchi
Shuji
S
Department of Laboratory Medicine, School of Medicine, Keio University, Tokyo, Japan.
Ishii
Keiko
K
Moriki
Takanori
T
Takeshita
Eiko
E
Murata
Mitsuru
M
Ikeda
Yasuo
Y
Watanabe
Kiyoaki
K
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D016466:CHO Cells; D020134:Catalytic Domain / Q000235:genetics; D006224:Cricetinae; D003412:Cricetulus; D003470:Culture Media / Q000032:analysis; D005091:Exons; D005174:Factor XII / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013912:Threonine / Q000378:metabolism*
D003470:Culture Media; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013912:Threonine; D005174:Factor XII