Endocrine Abstracts

Introduction: Prader–Willi syndrome (PWS) is characterised by hypotonia, obesity, short stature, and hypogonadism probably due to hypothalamic dysfunction (hypogonadotropic hypogonadism (HH)). Exaggerated adrenarche is however commonly noted in these patients. Early puberty is rarely described: we report two girls with PWS diagnosed with premature sexual maturation.

Case reports: Case 1: this 8-year-old girl was neonatally diagnosed with PWS (maternal uniparental disomy (MUPD)) of chromosome 15. At 2 years of age she started GH treatment to improve final height and muscle tone. At 6.5 years she was growing rapidly (height velocity 8.8 cm/year) and was B2 and PH3. On LHRH testing FSH increased from 6 to 39.3 U/l and LH from <0.2 to 7.6 U/l: compatible with her stage of puberty. Oestrogen was undetectable. Pelvic US showed 3.8×0.8×1.6 cm uterus; the right ovary was unidentified and the left ovary had a volume of 1 cc with a 6 mm follicle. GnRH analogue treatment was started for psychological reasons, and also to optimise growth potential. She has remained B2, P3.

Case 2: this 7-year-old girl was diagnosed with PWS due to MUPD of chromosome 15 at 2 years of age. GH therapy was commenced at 3.5 years to improve final height, tone, muscle mass and overall global development. At 6 years she developed pubic hair with no axillary hair or clitoromegaly. The height velocity was 7.5 cm/year. Investigations showed normal 17 OHP and adrenal androgens. Bone age was advanced by 1.8 years. She is currently PH3, Ax1 with B2: LHRH test and pelvic USS are ongoing.

Conclusion: Early puberty is uncommon in PWS, as patients characteristically have hypogonadotropic hypogonadism. Clinicians need to be aware that early puberty may also occur, although due to obesity initial signs of breast development may be masked.