Clinical and Molecular Cytogenetic Characteristics of Five Cases with Isodicentric Y Chromosome

Isodicentric Y chromosome [idic(Y)] is one of the most common structural abnormalities of the Y chromosome; it has been observed in patients with reproductive disorders and in patients with disorders of sexual development. Most idic(Y) chromosomes are found in mosaics with a 45,X cell line. These chromosomes are highly unstable during mitosis due to the presence of two centromers, which explains their probable loss in early mitosis or mitosis of the embryo, and therefore the presence of the 45,X line. It has been hypothesized that the proportion of 45,X cells in various tissues probably influences the phenotypic sex of individuals carrying an idic(Y) chromosome, ranging from infertile men, hypospadias, ambiguous genitalia, Turner syndrome to sex reversal. In this article we present five cases of patients with idic(Y) referred for suspected disorder of sex development (DSD), 3 with male assignment and 2 with female assignment, all cases have variable clinical characteristics, which were assessed by the transdisciplinary group of Disorders of Sex Development of the Hospital Universitario San Ignacio, Bogotá, Colombia. Patients were analyzed by conventional and molecular cytogenetics, using high-resolution G-band and fluorescence in-situ hybridization (FISH) techniques. Our findings highlight the importance of cytogenetic studies in the diagnosis of DSD patients.