Thrombocytopenia with absent radii (TAR) syndrome: a new increased cellular radiosensitivity syndrome.

Abstract A 70-year-old woman with congenital absence of both radii but preservation of the thumb developed a marked pancytopenia after two i.v. injections of 1 g of 5-fluorouracil (5-FU) 1 week apart. She developed bloody diarrhoea after nine fractions of 2 Gy to parallel opposed 16 × 15 cm abdominal fields. This unusual response prompted an investigation of the radiosensitivity of the patient's cells by the sensitive G 2 assay of transformed lymphocytes. The radiosensitivity of the patient's lymphoblastoid line appeared to be intermediate between that of normal individuals and an ataxia telangiectasia line. The clinical response and in vitro radiosensitivity testing suggest that the thrombocytopenia with absent radii (TAR) syndrome appears to be one of the inherited impaired DNA repair syndromes and is a very newly described radiation sensitivity syndrome. The development of three separate primary cancers in this patient (small bowel, ovary and bladder) suggests there is an increased risk of neoplasia in this condition.