Three Novel ADAMTS-13 Gene Mutations in Thrombotic Thrombocytopenic Purpura (TTP).

ADAMTS-13 is an enzyme which cleave von Willebrand factor (VWF) to prevent excessive platelet thrombus formation. Mutation of ADAMTS-13 is associated with congenital thrombotic thrombocytopenic purpura (TTP). In this study, we report three novel missense mutations of ADAMTS-13 gene in TTP families. Genetic analysis of ADAMTS-13 gene was performed in 6 TTP families. Three novel ADAMTS-13 gene mutations (2708C>T [S903L], 3650T>C [I1217T] and 3941C>T [S1314L]) detected in 3 families. They were all found with heterozygous genotype in exon 21, 26 and 28, respectively. The 3650T>C mutation was found at exon 26 in the patient and his mother. A heterozygous guanine to adenine substitution was found at 5′ splicing site of intron 3(IVS+ 1) in the patient, his brother and his father. The plasma ADAMTS-13 activities of the patient, father, mother, and brother were less than 3%, 56%, 55% and 62% respectively. ADAMTS-13 inhibitors were not detected in all family members. 3941C>T was found at exon 28 in the patient and her father. The plasma ADAMTS-13 activities of the patient, father, and mother were 96%, 83%, and 83% respectively.