Protein C deficiency Hong Kong 1 and 2: hereditary protein C deficiency caused by two mutant alleles, a 5-nucleotide deletion and a missense mutation.
We characterized a mutant protein C gene from an individual with no detectable protein C antigen in blood plasma. Southern blot hybridization analysis with human protein C cDNA demonstrated neither gross deletion nor rearrangement of the gene. Sequencing all the exons and exon-intron boundaries of the gene except the 3' noncoding region showed two mutant alleles. The one, derived from the mother, represents a deletion of 5 nucleotides (nt) (CCCGC) in the end of exon VI (mutation I), predicted to result in the generation of a new stop codon due to a reading frameshift and the premature termination of translation. The other, derived from the father, represents a point mutation (G to A) in exon IX (mutation II), resulting in an amino acid substitution, Gly-376(GGC) to Asp(GAC), in the catalytic domain of the protein. Allele-specific oligonucleotide probe hybridization confirmed the presence of the two mutations. Mutation I would result in a truncated polypeptide of 169 amino acid residues that lacks the heavy chain. Mutation II gives rise to an alteration of a highly conserved amino acid, Gly-376. These data indicate that this patient is a compound heterozygote of the two mutant alleles, each one inherited from each parent. Transient expression assays using COS-7 cells transfected with mutated protein C expression vectors suggested that each of the two mutations leads to the protein C deficiency by causing an impairment of secretion of the respective mutant proteins.
Sugahara
Y
Y
First Department of Medicine, Tokyo Medical and Dental University, Japan.
Miura
O
O
Yuen
P
P
Aoki
N
N
D000595:Amino Acid Sequence; D001483:Base Sequence; D015870:Gene Expression; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D010375:Pedigree; D016133:Polymerase Chain Reaction; D011486:Protein C / Q000235:genetics / Q000378:metabolism; D020151:Protein C Deficiency; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D014162:Transfection
D009838:Oligodeoxyribonucleotides; D011486:Protein C; D012333:RNA, Messenger