Cytogenetic and molecular genetic analysis of dicentric Y chromosome and its relation to male azoospermia

Cytogenetic analysis, Y-chromosome microdeletion screening, FISH
techniques and other genetic methods have helped in finding the causes of infertility in
azoospermic or severe oligoazoospermic cases in the last decade.
Objective: In the present study, we characterized an abnormal Y-chromosome, detected
as a mosaic in an azoospermic male ascertained for infertility.
Materials and Methods: Chromosome analysis, using G, Q and C banding techniques
and FISH analyses with several different DNA probes specific for Y and X
chromosome sequences [XY centromeric α-satellite, Y non-α-satellite III, LSI-probes of
the Y chromosome, WCP of Chromosome Y, SRY gene, subtelomeric Xp and Yp,
which cover the SHOX (short stature-homeobox containing) gene, and subtelomeric Xq
and Yq probes] were performed. A total of 20 sequence tagged sites were analyzed
using primer sets specific for the Y-chromosome microdeletion loci. The primers were
chosen to cover AZFa, AZFb, and AZFc regions as well as the SRY gene.
Results: Chromosome analysis revealed a gonosomal mosaicism of monosomy X
(51%) and a pseudodicentric Y (49%) chromosome: mos 45, X/46,X psu dic (Y)
(qter→p11.32 :: p11.2→qter).
Molecular genetic studies did not show deletions in the AZFabc regions, but a deletion
was found in the short arms of the dicentric Y chromosome. One of the SRY genes was
also missing.
Conclusion: The azoospermia in this patient could be explained by either the presence
of an abnormal Y-chromosome that cannot form a sex vesicle (which appears to be
necessary for the completion of meiosis process and the formation of sperm), or the
presence of the 45, X cell line