ADAMTS13 activity and genetic mutations in Japan

Area of Science:

• Genetics
• Hematology
• Molecular Biology

Background:

• Thrombotic thrombocytopenic purpura (TTP) is a severe condition caused by deficiency in the metalloprotease ADAMTS13.
• Over 100 genetic defects in the ADAMTS13 gene have been identified globally since 2001, significantly advancing TTP etiology understanding.

Purpose of the Study:

• To investigate age and gender differences in ADAMTS13 activity within the general population.
• To explore genotype-phenotype correlations of ADAMTS13 genetic polymorphisms.
• To estimate the prevalence of homozygous or compound heterozygous ADAMTS13 deficiencies.

Main Methods:

• Analysis of plasma ADAMTS13 activity using a quantitative assay.
• Genetic analysis of the ADAMTS13 gene in a Japanese general population cohort (3616 individuals, aged 30-80).
• Identification and characterization of genetic polymorphisms and mutations.

Main Results:

• ADAMTS13 activity decreased with age, while VWF antigen increased.
• VWF antigen levels were lowest in blood group O individuals; ADAMTS13 activity showed no association with ABO blood group.
• 25 polymorphisms were identified, including 6 missense and 19 synonymous mutations. P475S was specific to East Asians and associated with reduced ADAMTS13 activity.
• Prevalence of congenital ADAMTS13 deficiency in Japan was estimated at 1 in 1.1 million.
• Specific mutations (R193W, Q449*, C754Afs*24, C908Y) were found in multiple Japanese congenital TTP patients.

Conclusions:

• Genetic variations in ADAMTS13 significantly impact TTP risk and prevalence.
• Age is a key factor influencing ADAMTS13 activity.
• Certain ADAMTS13 mutations are disproportionately represented in the Japanese TTP population, suggesting founder effects or specific genetic predispositions.