The use of fluorescence in-situ hybridisation to clarify abnormal Y chromosomes in two infertile men.

OBJECTIVE

To characterise the structurally abnormal Y chromosomes present in two infertile men by means of the molecular technique of fluorescence in-situ hybridisation (FISH).

METHODS

Both men were phenotypically normal and had azoospermia. In Case 1 the karyotype with routine cytogenetics was 46,XX; in Case 2 it was complex, with 3 cell lines--45,X/46,X,i(Yp)/46,X,+?del(Y)(q11). We used probes from the Y chromosome and FISH to clarify these karyotypes.

RESULTS

In Case 1 a translocation of Y chromosome to the X chromosome was identified with FISH--t(X;Y). In Case 2, an isochromosome of the short arm of the Y chromosome was confirmed in one cell line, and another cell line was shown to contain a small Y chromosome with heterochromatic deletion. These findings explained the underlying pathogenesis in both cases.

CONCLUSIONS

Molecular investigation with FISH should become part of the routine investigation of infertile men with an abnormal Y chromosome.