Cytogenetic and FISH analysis in a boy with 48,xxyy syndrome

Numerical sex chromosome aberrations that include an addition or a deficiency of one of the sex chromosomes are relatively frequent in human pathology, occurring in 1 per 400 births. At the other hand, the addition of two or more sex chromosomes is an uncommon event, and little is known about the mechanism of origin, clinical symptoms and incidence of those disorders. 48,XXYY is a rare syndrome without pathognomonic clinical features, and therefore is usually diagnosed at late puberty or in adulthood. At this period the most constant and characteristic symptoms like tall stature, hypogonadism, gynaecomastia, mental retardation and behavioural problems come to full manifestation. In this report we present the results of cytogenetic and clinical studies in a child with hypotonia, mild dysmorphic features and developmental delay in whom cytogenetic analysis established the diagnosis of the 48,XXYY syndrome already in early childhood. The standard karyotype was confirmed by fluorescent in situ hybridization using centromere specific probes for chromosomes X and Y.