Constitutional aplastic anaemia: a family with a new X linked variety of amegakaryocytic thrombocytopenia.

A family is described in which three male members died in early infancy with severe thrombocytopenia and a fourth in adolescence with aplastic anaemia. One child was investigated in detail and shown to have amegakaryocytic thrombocytopenia, progressing to pancytopenia as a result of bone marrow hypoplasia. His associated congenital abnormalities differed from those described in Fanconi's aplastic anaemia, his chromosomes were normal, and the fetal haemoglobin level was 48%. Amegakaryocytic thrombocytopenia is itself rare and the index case appears unique. It is suggested that this family has a previously undescribed X linked variety of amegakaryocytic thrombocytopenia.