PAROXYSMAL-NOCTURNAL HEMOGLOBINURIA DUE TO AN 88-BP DIRECT TANDEM REPEAT INSERTION IN THE PIG-A GENE

Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired stem cell ab normality which frequently develops in patients with aplastic anaemia. The disease is due to somatic mutations in the PIG-A gene, and a vari ety of mutations have been reported, The majority are point mutations, or small insertions and deletions resulting in a frameshift. Previous insertions reported have all been within the range of 1-10 bp. We des cribe here a patient with PNH due to a large insertion of 88 bp; DNA s equencing showed this to be a tandem repeat of PIG-A sequences. The sa me mutation could be found in granulocytes and lymphocytes, indicating a pluripotent stem cell origin.