Ataxia-without-telangiectasia. Progressive multisystem degeneration with IgE deficiency and chromosomal instability.

Three of five siblings developed a progressive neurological disorder during infancy or early childhood characterized by cerebellar ataxia, choreoathetosis and peripheral neuropathy. Immunological studies revealed a marked selective deficiency of serum IgE in all three affected siblings. There was evidence of chromosomal instability in the three affected siblings and in one of the parents. One of the affected siblings also developed acute lymphoblastic leukaemia. In spite of many resemblances, this syndrome differs from classical or complete ataxia telangiectasia in that oculocutaneous telangiectases were lacking, the serum IgA and alpha-fetoprotein levels in this family were normal, there was no gonadal dysgenesis, and the cytogenetic findings were atypical.