Protein C deficiency: Identification of a novel two‐base pair insertion and two point mutations in exon 7 of the protein C gene in Spanish families

We have applied single‐strand conformation polymorphism (SSCP) to the analysis of exon 7 of the anticoagulant protein C (PC) gene, in 13 PC‐deficient Spanish families. Abnormal patterns were visualized in three samples from type I or quantitative PC deficient proposita. A previously undescribed mutation due to a TT insertion after nucleotide 6139, between codons Gly‐142 and Arg‐143 was found in one family. The mutation (6139,ins TT) should result in a frameshift with a stop at codon 156, which agrees with the presence of a type I or quantitative PC deficiency in the affected members of the family. The second mutation identified was a C to T transition at nucleotide 6274, 9 base pairs into intron G. This mutation (6274,C→T), found for the first time in a Spanish family, is identical to the previously characterized PC Sant Louis. The third mutation was a G to A transition that replaces arginine 178 with glutamine (178,R→Q). This is the third case of 178,R→Q mutation in 17 apparently unrelated Spanish families with type I PC deficiency. Furthermore, SSCP analysis allowed the detection of another previously described mutation in a PC‐deficient Spanish family (178,R→W). © 1992 Wiley‐Liss, Inc.