ESPE Abstracts

Introduction: Isodicentric Y chromosome[idic(Y)] is one of the most common structural abnormalities of the Y chromosome and has been observed in patients with disorders of sexual development. Most idic(Y) chromosomes are found in mosaic form with a 45, X cell line.

Methods: The aim of this study was to investigate the genotype and phenotype variability of patients with idic(Y). The clinical data from five patients was extracted from medical records in a tertiary care centre after consent was obtained.

Results: Isodicentric Y chromosomes were found in all five patients. Four out of the five isodicentric Y chromosomes had a breakpoint in Yq11.2. i),ii) Two cases presented at birth with hypospadias, phallus, bifid scrotum and unilateral cryptorchidism. No Mullerian structures were noted on imaging and both children were raised as male. Proportion of 45 X cell line was 30% in one and 73% in the other. iii) A 4 month old baby presented with perineal hypospadias, 2.7 cm phallus, bifid scrotum and bilateral cryptorchidism. Uterine like structure was noted on imaging. Child was raised as male. Proportion of 45 X cell line was 30%. iv) A 2.5 years old child presented at birth with hypospadias, 2.1 cm phallus, bifid scrotum and bilateral cryptorchidism. Pelvic ultrasound revealed an uterine-like structure. Child underwent laparoscopic examination whereby left orchidopexy was done and right gonad was removed. Pathology showed no ovarian stroma and was consisted with immature testicular tissue. Proportion of X cell line was 37% and the child was raised as a boy. v) A15 year old raised as female presented with delayed puberty and virilization (cliteromegaly, deepening of voice). Uterine like structure was noted on imaging however no gonads were identified. Proportion of 45X cell line was 36%.

Conclusion: There is a wide range of somatic, genital, and gonadal phenotypic manifestations among patients with an isodicentric Y. This phenotypic variability could be attributed to various factors such as the proportion of the 45,X cell line and on the various locations of the breakpoints. However it is likely that there may be other factors which may influence this. The incorporation of cytogenetic and molecular techniques would offer a more comprehensive understanding of this structural chromosomal abnormality. This would aid counselling in terms of gender assignment and fertility.