Abstract
Reciprocal Y autosome translocations are rare but frequently associated with male infertility. We report on the meiotic outcome in embryos fathered by two males with the karyotypes 46,X,t(Y;4)(q12;p15.32) and 46,X,t(Y;16)(q12;q13). The two couples underwent preimplantation genetic diagnosis (PGD) enabling determination of the segregation types that were compatible with fertilization and preimplantation embryo development. Both PGD and follow up analysis were carried out via fluorescence in situ hybridization (FISH) or array comparative genomic hybridization (aCGH) allowing the meiotic segregation types to be determined in a total of 27 embryos. Interestingly, it was seen that the number of female embryos resulting from alternate segregation with the chromosome combination of X and the autosome from the carrier gamete differed from the corresponding balanced males with derivative Y and the derivative autosome by a ratio of 7:1 in each case (P = 0.003) while from the adjacent-1 mode of segregation, the unbalanced male embryos with the combination of der Y and the autosome were seen in all embryos from couple A and in couple B with the exception of one embryo only that had the other chromosome combination of X and derivative autosome (P = 0.011). In both cases the deficit groups have in common the der autosome chromosome that includes the segment Yq12 to qter. The most likely explanation may be that this chromosome is associated with the X chromosome at PAR2 (pseudoautosomal region 2) in the sex-body leading to inactivation of genes on the autosomal segment that are required for the meiotic process and that this has led to degeneration of this class of spermatocytes during meiosis.
Highlights
Reciprocal Y autosome translocations are rare but frequently associated with male infertility
Follow up of the remaining three embryos by array comparative genomic hybridization (aCGH) gave results showing two embryos (C1E2, C1E3), to be female but with additional aneuploidies unrelated to the chromosomes involved in the translocation and confirmed one (C3E3) as an unbalanced male embryo with additional aneuploidy (Table 3)
We have reported the detailed analysis of the translocated chromosome constitution of the embryos generated by preimplantation genetic diagnosis (PGD) in two couples where the male partner has a Y- autosome translocation
Summary
Reciprocal Y autosome translocations are rare but frequently associated with male infertility. An infertile man with severe oligoasthenospermia was found to have the karyotype 46,X,t(1;Y) (q11;q11) His father who was proved to have the same translocation, had two daughters and one other son [5]. The report of the family investigated by (Sklower Brooks et al in 1998), describes a couple where the male had the abnormal karyotype 46,X,t(Y;8)(q12;p21.3) and the woman had reported a third miscarriage involving the t(Y;8) translocation. The investigation revealed that their deceased father must have carried the abnormal karyotype which was passed on to four of his sons in a balanced state and in an unbalanced state to the remaining one [6]
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