Efficacy and safety of sirolimus therapy in familial hypoinsulinemic hypoglycemia caused by AKT2 mutation inherited from the mosaic father.

Activating mutation in the insulin signal-transducing kinase AKT2 results in severe hypoinsulinemic hypoketotic hypoglycemia and a characteristic phenotype of possible overgrowth and, sometimes, acanthosis nigricans. Herein, we describe a metabolic and hormonal profile before and during treatment with sirolimus in two brothers with AKT2 mutation inherited from the mosaic father, who showed low-level mosaicism in sperm. The boys, aged 1 and 14, who had severe non-insulin-dependent hypoketotic hypoglycemia and a typical dysmorphism, were admitted to endocrinology department for the analysis of their metabolic parameters: lipids, lactate, ammonia, glucose, insulin, c-peptide, and hormones (GH, IGF1, IGFBP3, TSH, fT4, cortisol, ACTH) before and during treatment with sirolimus. Previously, they had been treated with high-carbohydrate diet. The brothers were started on sirolimus with subsequent normalization of glycemia and reduced carbohydrate feedings overnight. The lowest fasting glucose levels improved from 20 mg/dl to 45 mg/dl in both sibs. The BMI of both brothers significantly dropped. After 6 months of sirolimus therapy we did not observe any laboratory or clinical side effects of the treatment.