[Chromosomal instability in homo- and heterocygocity for microcephalia vera )author's transl)].

In a family with microcephalia vera, not only the 3 microcephalic probands, but also their healthy mother showed a significantly increased rate of spontaneous structural chromosomal aberrations in cultures of lymphocytes of the peripheral blood. Thus an increased aberration rate in the lymphocytes of asymptomatic family members could serve as a sign of heterocygocity. The qualitative analysis revealed aberrations of the chromatid and chromosomal type; exchanges that are frequently found in Fanconi's and Bloom's syndrome could not be detected. Therefore it can be assumed that the chromosomal instability of microcephalia vera is caused by a specific mechanism.