Nouveaux mécanismes moléculaires impliqués dans l’insensibilité à l’hormone de croissance

[Laron syndrome: Presentation, treatment and prognosis]

Laron syndrome is a rare cause of short stature due to an abnormality of growth hormone receptor (GHR). It is characterized by poor phenotype-genotype correlation and geographic predilection essentially in the Mediterranean rim, the Middle East and Indian subcontinent. This syndrome corresponds to an endogenous and exogenous complete insensitivity of GH and manifests by early hypoglycemia, an extremely severe short stature and dysmorphic features contrasting with high levels of circulating GH. To date, treatment with recombinant IGF1 is the only treatment option that has improved the terrible prognosis in these patients but does not actually realize the conditions for genuine replacement therapy.

[Noonan's syndrome and growth hormone treatment]

Noonan's syndrome is a clinical entity associating short stature, facial dysmorphy and congenital cardiomyopathy. In 50 % of cases, PTPN11 mutations are found, transmitted as an autosomal dominant trait. Mutations of other genes (KRAS, SOS1) were also recently reported. Short stature could be due to GH deficiency, abnormal neurosecretory function or GH insensitivity. GH treatment induces height gain, even if only few studies reported data on final height. Response to GH varies, depending on the presence of PTPN11 mutations. No cardiac adverse effects were reported to date with GH treatment in Noonan's syndrome.