Congenital hypomegakaryocytic thrombocytopenia associated with bilateral absence of the radius - the TAR syndrome.

A case of the TAR syndrome is described which presented bilateral absence of the radius and pronounced thrombocytopenia at birth; when seen at the age of 6, growth and development was within normal limits, except for the upper extremities, and no signs of an haemorrhagic diathesis were seen. A careful family study brought 2 additional cases to light: a female second cousin was found to have bilateral absent radius, but no haematological abnormalities when seen at the age of 10. Her younger brother had died at the age of 3 months with severe thrombocytopenia and heavily malformed, flipper-like upper extremities. The broad clinical variation of the syndrome should be kept in mind in genetic studies and counselling.