Reduced male fertility can be caused by genetic factors affecting gamete formation or function; in particular, chromosome abnormalities are a possible cause of male subfertility as shown by their higher frequency in infertile men than in the general male population. Meiotic studies in a number of these males have shown spermatogenesis breakdown, often related to alterations in the process of chromosome synapsis. Indeed, any condition that can interfere with X-Y bivalent formation and X-chromosome inactivation is critical to the meiotic process; furthermore, asynapsed regions may themselves represent a signal for the meiotic checkpoint that eliminates spermatocytes with synaptic errors. We performed cytogenetic, hormonal and seminal studies in 333 infertile patients selected because azoospermic, severely oligozoospermic or normozoospermic with failure to fertilize the partner's oocytes in an in vitro fertilization (IVF) program. Our findings: 1) confirm the high incidence of chromosomal anomalies among infertile males; 2) highlight the relevance in male infertility of quantitative/positional modifications of the constitutive heterochromatin; and 3) underline the relevance of cooperation between andrologists and cytogenetists prior to every kind of assisted reproduction, above all prior to intracytoplasmic sperm injection, in which selective hurdles eliminating abnormal germ cells are bypassed.

We identified a subgroup of ataxia-telangiectasia (AT) patients (2 sibs and 1 unrelated case) characterized by typical clinical manifestations of the disease and cellular radiosensitivity intermediate between classical AT and normal subjects. Our data and a literature review of the intermediate radiosensitivity AT cases show that radioresistant DNA synthesis, cellular radiosensitivity (measured in terms of survival and chromosome breakage), and the clinical hallmarks behave independently. This raises a number of interesting questions about the correlation between radiobiological and clinical features, and about the nature of the AT gene(s).

Cytogenetic investigations performed on lymphocytes from a 29-year-old woman with no severe anomalies, allowed us to recognize a mild form of Roberts syndrome. The proposita's metaphases showed a consistent centromere splitting, especially affecting chromosomes 16, 19, 21, and 22. This centromere separation sequence seems to be unique to Roberts syndrome cells. The experiments also showed that no diffusible factor, involved in the mechanism of sister chromatid pairing-disjunction, exists.

No abstract

In the present study we examined cells from several patients clinically diagnosed as having ataxia-telangiectasia (AT), for the capacity of their cells to inhibit DNA synthesis following exposure to gamma irradiation, and for the rate of spontaneous or bleomycin-induced chromosomal aberrations. Cells from two patients showed normal inhibition of DNA synthesis and levels of induced chromosomal aberrations intermediate between normal and AT cells. These two patients had only minimal immunologic impairment. These findings appear to define one distinct subset of AT.