Turner syndrome is characterized by short stature, gonadal dysgenesis and a variety of somatic features and major organ malformations. About 50% of the patients have a 45,X karyotype, while the remainder have structurally abnormal sex chromosomes or mosaicism including mos 45,X/46XY. Those with Y chromosomal material are at increased risk for developing gonadoblastoma or dys­germinoma later in life. The SRY gene on Yp has a major role in sexual differentiation, being the primary testicular determinant. Detection of the SRY gene in Turner syndrome patients has important clinical and therapeutic implications.

      We performed a genetic study of 40 Turner syndrome patients for cytogenetics (G banding) and polymerase chain reaction (PCR) for the SRY gene using XES7/XES2 and SRY 1F/SRY 2R primer sets. Cytogenetics identified a 45,X karyotype in 50%, isochromosomes in 25%, proximal long or short arm deletions and markers in 7.5% and mos 45,X/46XY in 5% of the patients. The SRY gene was detected in blood leucocytes of only two of the patients with the mos 45,X/46XY karyotype. Our low incidence of SRY-gene positive results in Turner syndrome patients contrasts with reported studies using more sensitive techniques that have detected a higher percentage. The increased risk of gonadoblastoma and the necessity of timely referral for gonadectomy require that analysis of the SRY gene should be offered to all Turner syndrome patients.

      Key words: Karyotype, SRY gene, Turner syndrome