45,X/46,X,i(Yp): Importance of Assessment and Support during Puberty and Adolescence.

The Y-chromosome genes are primarily involved in sex determination, stature control, spermatogenesis, and fertility. Among structural rearrangements of the Y chromosome, the isochromosome of Yp, i(Yp), appears to be the most uncommon. We describe a detailed evolution of puberty in a boy with 45,X/46,X,i(Yp). Array CGH found 2 cell lines, one with i(Yp) and the other with monosomy X. Genetic analysis of currently known genes involved in Kallmann syndrome/normosomic central hypogonadotropic hypogonadism showed no abnormality. The patient presented with a pubertal course suggestive of a delayed puberty with gynecomastia, reduced growth rate, and infertility that need testosterone treatment to induce the appearance of the secondary sex characteristics. This patient shows the potential effects of i(Yp) and emphasizes the importance of appropriate management of puberty in people with 45,X/46,X,i(Yp). Early hormone treatment, concerns regarding fertility, emotional support, and a successful transition to adult care may help improve the physical and psychosocial well-being of affected patients.