Ring chromosome Y syndrome

Ring chromosome Y syndrome (also known as ring Y chromosome or r(Y) syndrome) is a rare chromosomal disorder in which the Y chromosome forms a ring structure due to deletions of genetic material at both ends (short arm and long arm) of the chromosome, followed by fusion of the remaining ends. The clinical presentation is highly variable and depends on the size and location of the deleted segments, as well as the degree of mosaicism (the proportion of cells carrying the ring chromosome versus those with a normal or absent Y chromosome). Ring Y chromosomes are often unstable during cell division, leading to mosaic karyotypes that frequently include a 45,X cell line. The syndrome primarily affects the reproductive and endocrine systems. Clinical features can range from a phenotypically normal male with infertility to ambiguous genitalia, mixed gonadal dysgenesis, or features consistent with Turner syndrome (45,X) in individuals where the ring Y is lost in a significant proportion of cells. Common manifestations include short stature, gonadal dysgenesis, hypospadias, cryptorchidism, and impaired spermatogenesis leading to azoospermia or severe oligospermia. In some cases, individuals may present with female or ambiguous external genitalia despite carrying Y-chromosomal material. The presence of Y-chromosomal material in individuals with gonadal dysgenesis carries an increased risk of gonadoblastoma, a gonadal tumor, which necessitates careful monitoring and potential prophylactic gonadectomy. There is no cure for ring chromosome Y syndrome. Management is multidisciplinary and tailored to the individual's phenotype. Treatment may include hormone replacement therapy (testosterone supplementation in males with hypogonadism or estrogen/progesterone in individuals raised female), surgical correction of genital anomalies, growth hormone therapy for short stature, fertility counseling, and surveillance for gonadal tumors. Psychological support and genetic counseling are important components of care.

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