A rare case in literature: Isochromosome Xq in Klinefelter syndrome

Klinefelter syndrome(KS), affecting 1 in 500-1,000 newborn males, is the most common sex chromosome aneuploidy among males with primary hypogonadism. Isochromosome Xq on the other hand is a rare variant of Klinefelter syndrome, accounting approximately 0.3% of all KS and associated with normal height and androgenisation compared to classical KS. Here, we present a case of isochromosome Xq variant of KS with similar clinical and cytogenetic findings with the few cases reported before.

A 25-year-old male patient referred to our clinic with complaint of infertility. He is the son of a consanguineous couple who are first cousins and there was no family history of reproductive difficulty. In physical examination synophrys, prominent ear and small testicles noted. The patient's spermiogram showed azoospermia and scrotal USG revealed testicular atrophy.

Karyotype analysis using G-banding resulted as 47,X,i(X)(q10),Y, and STR analysis showed no deletion in AZF and SRY loci of interest.

Although several isochromosome Xq variant of KS cases can be found in literature, it is our duty to emphasise the importance of karyotyping for patients with reproductive difficulty who may not have all features of classical Klinefelter syndrome.