Male with 45,X/46,X(r)Y Mosaicism due to a Ring Y Chromosome: A Case Report

Figure 1: Credit: U.S. National Library of Medicine. A ring chromosome is an extremely rare chromosomal aberration, which can occur in autosomes and sex chromosomes. The frequency of a ring chromosome in clinically detectable conceptions is 1/25,000 however, the incidence of the ring Y chromosome is unknown [1]. The formation of a ring Y chromosome involves terminal breakage in both chromosomal arms (p and q arms) and fusion of the resulting ends with loss of the deleted distal material (Figure 1). Because of the instability of a ring Y chromosome during mitosis, a second monosomic cell line is often present in these patients [2]. There are several mosaicisms reported with ring Y chromosomes including 45,X/46,XX/46X(r)Y, 45,X/46,XY/46,X(r)Y, 46,XX/47,XX(r) Y, 45,X/46,X(r)Y, 45,X/46,X(r)Y/46, X, dicr Y [3]. Patients with mosaic 45, X/46,X(r)Y karyotype, present with phenotypes ranging from females with Turner-like phenotypes, phenotypic males and females with mixed gonadal dysgenesis, to almost phenotypic normal males [4,5]. Variability of phenotype depends on the percentage of monosomic cells in different tissues and Abstract