Homozygous protein C deficiency with purpura fulminans: report of a new case and a description of a novel mutation.

We report here a quite rare case of severe homozygous protein C deficiency. The index case is a 9-month-old Saudi boy who was born after an uneventful pregnancy at 39 weeks. The diagnosis of epidermoloysis bullosa and the appearance of scrotal haematoma raised the diagnosis of thrombosis due to protein C deficiency. The clinical presentation and extremely low level of protein C activity (< 0.01 U/ml) in the index case suggested a severe case of protein C deficiency. The father is 28 years old and the mother is 25 years old and are consanguineous. Neither had a personal or family history of thrombosis. Genomic DNA was extracted from peripheral blood of the patient and both parents, exons of protein C were amplified by polymerase chain reaction and sequenced. Sequencing revealed the presence of a novel CCTG duplicate nucleotide (effective insertion) after nucleotide 8826 in exon 9 of the protein C gene. This insertion is found in the homozygous state in the patient and in the heterozygous state in both parents. It results in a frame-shift mutation, which introduces a stop-codon, thereby generating a prematurely truncated protein. These molecular findings agree with the presence of quantitative protein C deficiency in the index case.