Endocrine Abstracts

Case history: A 30 years old male Caucasian had his saliva tested on a self-funded commercial DNA testing to identify his ancestral roots. The markers for Y chromosome were found to be absent and further evaluation revealed him to have 46 XX karyotype.This was consistent with the diagnosis of De la Chapelle syndrome or XX male syndrome. Fluorescence in situ hybridization (FISH) studies confirmed the presence of SRY (sex determining region Y) gene which was responsible for his male phenotype. In view of the symptoms of hypogonadism he was referred to our endocrinology clinic for further investigations and management. He described himself as generally fit and well but struggled to manage his weight despite going to the gym regularly. He had a difficult time with bullying at school. Puberty was achieved at around age 14 but he had concerns over the years regarding his development in comparison to other boys of a similar age. On examination he was obese with BMI of 49.9 kg/m². He had sparse pubic and axillary hair and bilateral gynaecomastia. Scrotal sac was small with only left testis palpable which was about 3 ml in size. The right testis was absent and his penis was small. Rest of the systemic examination was unremarkable.

Investigations: Testosterone level 6.2 nmol/l (normal range: 8.0–30.0); Follicle stimulating hormone (FSH) – 20.3 IU/l (normal: 1.0–12.0), Luteinising Hormone (LH) – 9.9 IU/l (normal: 1.0–9.0). Oestradiol was 122 pmol/l (normal: <160). Thyroid function test, prolactin and insulin like growth factor (IGF-1) were normal. Testicular ultrasound showed small left testis measuring 25×10×22 mm but right testis was absent in the scrotal sac as well as inguinal canal. MRI pelvis confirmed that there was no testicular tissue along the course of the right inguinal canal or within the right sided retroperitoneum.

Treatment: He was commenced on topical testosterone with Testogel 50 mg daily which markedly improved his hypogonadal symptoms as well as his serum testosterone. He had an improvement in energy levels, libido and facial hair growth.

Conclusions and Discussion points: De la Chapelle syndrome is a rare cause of hypogonadism. Commerical DNA testing is becoming increasingly common. (1) Is there a need to regulate this industry? (2) What is the best management strategy to address all the issues in XX male syndrome?