Two cases of Y; autosome translocations: A 45, X male and a clinically trisomy 18 patient

Abstract

We report on 2 cases of Y; autosome translocations. One is a male with normal external genitalia and 45,X karyotype without evidence of mosaicism or apparent translocation on cytogenetic analysis. In situ hybridization showed that the euchromatic portion of the Y-chromosome is translocated to the chromosome 15. The other case is a clinically trisomy 18 male patient, with modal number of 46, a small metacentric marker with appearance of an i(18p) and cytogenetic and molecular evidence of Y;18 translocation. The occurrence of Y;18 translocation associated with clinical signs of trisomy 18 is reported here for the first time.

Clinical management of a rarede novo translocation 46,X,t(Y;15) (p11.2∼11.3;q11.2).ish t(Y;15)(DYZ3+,AMELY+,SNRPN+;D15Z+) found prenatally

“…The Y/15 non-reciprocal translocation involving Yp with breakpoints on Yq and 15q is a frequent rearrangement in 45,X males (Farah et al, 1994) and has also been reported in patients with Prader-Willi syndrome (Qumsiyeh et al, 1992). In this prenatal study, a Y/15 reciprocal translocation was shown to involve rearrangement of the entire Y long arm up to the short arm breakpoint Yp11.211.3 to 15q11.2qter.…”

A 45,X sterile male with Yp disguised as 21p

“…So far, an apparent nonmosaic 45,X karyotype concomitant with a translocation of a Y chromosome euchromatic segment including all or part of Yp onto an autosome has been documented in about 24 male patients (mostly children) [Farah et al, 1994;Hsu, 1994;Gimelli et al, 1996]. Among these, there are five instances in which the translocation was ascertained in adult individuals: three sporadic sterile males [Turleau et al, 1980;Gal et al, 1987;Andersson et al, 1988;Arnemann et al, 1991] and two families with proven fertility of the male carriers [Subrt and Blehová , 1974;Callen et al, 1987;Andersson et al, 1988].…”

“…Indeed, the appurtenance of the Y and the acrocentric chromosomes to the alphoid suprachromosomal family 4 [Alexandrov et al, 1993] along with the hydrid Y;21 centromere here documented is consistent with this view. The exceptional participation of chromosome 21 and the still unreported involvement of chromosome 13 in 45,X males with a variable amount of Y-euchromatin resulting from a Y;autosome translocation (the male patients with obvious Y;13 translocations described by Boutouil et al [1997] and Shanske et al [1999] are excluded from this class mainly because the rearrangements involved the entire or almost entire Y chromosome including Yqh) plausibly reflect the poor representation of these chromosomes in the whole group of Y;autosome translocations [Farah et al, 1994;Hsu, 1994;Gimelli et al, 1996].…”

“…So-called 45,X males have seldom been described [Farah et al, 1994;Hsu, 1994;Gimelli et al, 1996]. Although they have male external genitalia and testes, sexual development may be abnormal, as it is illustrated by the sterility documented in four out of six 45,X instances documented in adult males [Subrt and Blehová , 1974;Turleau et al, 1980;Callen et al, 1987;Gal et al, 1987;Andersson et al, 1988;Arnemann et al, 1991;Copelli et al, 2000].…”

“…Although they have male external genitalia and testes, sexual development may be abnormal, as it is illustrated by the sterility documented in four out of six 45,X instances documented in adult males [Subrt and Blehová , 1974;Turleau et al, 1980;Callen et al, 1987;Gal et al, 1987;Andersson et al, 1988;Arnemann et al, 1991;Copelli et al, 2000]. This peculiar karyotype mostly results from Y;autosome translocations allowing for the preservation of Yp or at least of SRY; so, the resulting phenotype heavily depends on the amount of Y-euchromatin present and on whether or not an euchromatic autosomal deletion has occurred [Andersson et al, 1987;Farah et al, 1994;Hsu, 1994;Gimelli et al, 1996]. We report on the first case of a Y;21 translocation in a 45,X patient who represents the fifth sterile male with apparent loss of the long arm of the Y chromosome.…”