Klinefelter syndrome in a patient with double Y-autosomal translocation

Klinefelter syndrome is one of the most common chromosomal abnormalities and the most common genetic cause of male infertility. About 85 % of patients have 47,XXY karyotype, other patients have other non-mosaic and mosaic Klinefelter syndrome variants. We report a unique clinical case — Klinefelter syndrome patient with double Y autosomal translocation. The proband is a 15-year-old male patient (height 180 cm, weight 50 kg, normal IQ) who was admitted for cytogenetic examination and genetic counseling due to delayed puberty. He was diagnosed with testicular hypoplasia, hypergonadotropic hypogonadism, pituitary microadenoma and left-sided varicocele. The proband was born in a nonconsanguineous marriage after in vitro fertilization due to paternal male factor infertility. Cytogenetic analysis was performed on cultured peripheral blood lymphocytes using standard chromosome analysis with GTG staining and FISH analysis. Molecular analysis of the Y chromosome was performed by multiplex PCR. Complex cytogenetic examination revealed a 46,XX,der(Y) t(Y;15)(q12;q11.1),der(13)t(Y;13)(q12;p11.2),-15 karyotype in the proband. Molecular analysis showed that the proband is SRY positive; no microdeletion of the Y chromosome was found. The detected double Y autosomal translocation is a chromosomal abnormality independent of KS. The father of the proband is an oligozoospermic man with robertsonian translocation 13;15 — 45,XY,der(13;15)(q10;q10), the mother has a normal karyotype 46,XX. Apparently, the der(13) and der(Y) chromosomes result from abnormal meiotic recombination in paternal meiosis between the heterochromatic region Yq12 and the centromeric/pericentromeric heterochromatin of chromosomes 13 and 15 involved in the paternal robertsonian translocation, and Klinefelter syndrome is due to the presence of two X chromosomes in the karyotype in the presence of a derivative Y chromosome. The detected double Y-autosomal translocation is a chromosomal abnormality unrelated to Klinefelter syndrome, arising on the background of the paternal robertsonian translocation.