Thrombotic thrombocytopenic purpura (TTP) is characterized by life-threatening destruction of intravascular erythrocytes and platelets, by mechanisms that remain poorly understood. In October 4 Nature Gallia Levy and colleagues from University of Michigan Medical Center, Ann Arbor show that a deficiency in a member of the ADAMTS family of zinc metalloproteinase genes (ADAMTS13) is the cause thrombotic thrombocytopenic purpura.

Levy et al. performed a genome-wide linkage analysis in four families with congenital TTP and mapped the responsible genetic locus to chromosome 9q34. Analysis of the genomic DNA of the patient showed 12 mutations in the ADAMTS13 gene on chromosome 9q34, accounting for 14 of the 15 disease alleles studied (Nature, 2001, 413:488-494).

"Because the exact location of the ADAMTS13 gene within the human genome has been mapped, gene therapy — along the lines being explored for treating haemophiliacs — may be a realistic option...