A rare variant Klinefelter syndrome seen 40 years later: 47,X,del(Xq24),Y

Patients with Klinefelter syndrome (KS) show a typically 47,XXY karyotype; however, some variations have been observed, including 47,XX,der(Y), 46,XY/47,XXY, 48,XXXY, 48,XXYY, and mosaicism or structural sex chromosome abnormalities in some patients. In the literature, a rare KS variant, 47,X,del(Xq),Y karyotype, was reported in only a few cases prior to 1981. A 40-year-old man (IV-3) was referred to our department due to infertility. His phenotype did not differ from the classic KS phenotype. He had two siblings (1-male; 1-female). His brother (IV-5) had mental retardation and died one year earlier at age 32. Additionally, his sister (IV-2) also had a history of infertility due to her husband's azoospermia. His mother had a history of 12 miscarriages. Karyotype analysis revealed the 47,X,del(Xq24),Y karyotype, and no deletions were seen in the AZF and SRY regions. We thought this chromosomal abnormality in the patient might have resulted from X-autosome translocation in one of his parents since his mother had recurrent pregnancy loss and his sibling had mental retardation. However, we could not confirm it due to his parents were not alive. This study shows the first case of a long-arm X-chromosome deletion after a long period and reviews current knowledge concerning variant KS (deletion Xq).