Chromosome analysis in a 31‐year‐old woman referred for primary amenorrhea, revealed a very high incidence of chromosome aberrations. She had microcephaly and immunodeficiency. Her healthy parents were consanguineous (1/32) and a younger sister, also with primary amenorrhea, died when 20 years old with a malignant lymphoma.
Chromosome studies were performed on lymphocytes and fibroblasts and in both tissues a high proportion of metaphases with multiple chromosome aberrations was found. Clonal and sporadic rearrangements, consisting of balanced and unbalanced translocations and dicentric chromosomes were more numerous than chromatid and chromosome breaks. In the lymphocytes the same unbalanced translocation t(8q;21q) was present in about 59% of the metaphases. Rearrangements involving chromosomes 7 and 14, similar to those described in patients with ataxia‐telangiectesia were found, but with a lower frequency. Sister Chromatid Exchanges were not increased. Chromosome and chromatid abnormalities were enhanced after exposure of cells to mitomycin C but not after exposure to the radiomimetic drug bleomycin.
Clinical and cytogenetic characteristics of the patient are compared with those of syndromes (Ataxia‐Telangiectesia and Werner's syndrome) or isolated cases (Weemaes et al. 1981, Sperling 1983, Spinner et al. 1985) whose features are similar to those of our patient. This case might represent a new chromosome instability syndrome due to a recessive mutation.
Two previous single case reports from the literature showed the presence or absence of centromeric antigens at the site of the inactive centromeres in one (X;X) and in one (9;11) dicentric chromosome. We studied nine different dicentric chromosomes using anticentromeric antibodies and immunofluorescence techniques. In the four autosomal dicentrics the inactive centromere was consistently positive while the dicentrics composed of two X chromosomes were either positive or negative; one case of (X;Y) dicentric was negative. The results indicate that the X chromosome mode of replication may be involved in the suppression of immunofluorescence at the site of the inactive centromere and that one centromere of the dicentric chromosome may lose its function but conserve some of its antigenic properties. This indicates that not all these antigens play a rôle in the microtubules-centromere interaction.
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