Hypogonadotropic Hypogonadism and Short Stature in Patients with Diabetes Due to Neurogenin 3 Deficiency

CONTEXT: Biallelic mutations in NEUROG3 are known to cause early-onset malabsorptive diarrhea due to congenital anendocrinosis and diabetes mellitus at a variable age. No other endocrine disorders have been described so far. We report four patients with homozygous NEUROG3 mutations who presented with short stature and failed to show any signs of pubertal development. CASE DESCRIPTION: Four patients (two males, two females) were diagnosed with homozygous mutations in NEUROG3 on the basis of congenital malabsorptive diarrhea and diabetes. All four had severe short stature and failed to develop secondary sexual characteristics at an appropriate age, despite some having normal body mass index. The absence of gonadal function persisted into the third decade in one patient. Upon testing, both basal and stimulated LH and FSH levels were low, with the remaining pituitary hormones within the normal range. Magnetic resonance imaging scans of the hypothalamic-pituitary axis did not reveal structural abnormalities. A diagnosis of hypogonadotropic hypogonadism was made, and replacement therapy with sex hormones was started. CONCLUSIONS: The high reproducibility of this novel phenotype suggests that central hypogonadism and short stature are common findings in patients with mutations in NEUROG3. Growth rate needs to be carefully monitored in these patients, who also should be routinely screened for hypogonadism when they reach the appropriate age. NEUROG3 mutations expand on the growing number of genetic causes of acquired hypogonadotropic hypogonadism.