A family case of fertile human 45,X,psu dic(15;Y) males

We report on a familial case including four male probands from
three generations with a 45,X,psu dic(15;Y)(p11.2;q12) karyotype.
45,X is usually associated with a female phenotype and only rarely
with maleness, due to translocation of small Y chromosomal
fragments to autosomes. These male patients are commonly infertile
because of missing azoospermia factor regions from the Y long arm.
In our familial case we found a pseudodicentric translocation
chromosome, that contains almost the entire chromosomes 15 and Y.
The translocation took place in an unknown male ancestor of our
probands and has no apparent effect on fertility and phenotype of
the carrier. FISH analysis demonstrated the deletion of the
pseudoautosomal region 2 (PAR2) from the Y chromosome and the loss
of the nucleolus organizing region (NOR) from chromosome 15. The
formation of the psu dic(15;Y) chromosome is a reciprocal event to
the formation of the satellited Y chromosome (Yqs). Statistically,
the formation of 45,X,psu dic(15;Y) (p11.2;q12) is as likely as the
formation of Yqs. Nevertheless, it has not been described yet. This
can be explained by the dicentricity of this translocation
chromosome that usually leads to mitotic instability and meiotic
imbalances. A second event, a stable inactivation of one of the two
centromeres is obligatory to enable the transmission of the
translocation chromosome and thus a stably reduced chromosome
number from father to every son in this family.