Pubertal development in the Prader-Labhart-Willi syndrome.

The sexual maturation in the Prader-Labhart-Willi (PLW) syndrome was investigated in 14 patients, 10 females and 4 males. A wide variability in the pattern of pubertal development was found including delayed puberty in 5 patients and normal puberty in 4 patients; sexual precocity was also observed in 5 patients, true precocious puberty in one patient and incomplete sexual precocity in the form of precocious pubarche in 4 patients. In 5 patients, 3 of them with precocious pubarche, the appearance of the pubertal signs was followed by a delay or arrest in their future development. An LH-RH stimulation test was performed in 11 patients. In the 6 patients who eventually developed normal puberty, the basal levels and the peak responses of both LH and FSH were within the range of those observed in normal controls of the same pubertal stage. In 4 patients showing marked delay or arrest of puberty, the basal levels were normal or low and the responses of LH and FSH to LH-RH were blunted. Priming with repeated LH-RH stimulation in one of the male patients led to an augmented LH response, suggesting a hypothalamic hypogonadotrophism. It is concluded that the lack of uniformity in the pattern of sexual maturation in the PLW syndrome is due to a variability in the location and extent of a hypothalamic lesion, which may comprise an active process continuing beyond the perinatal period.