MECASERMIN TREATMENT OF A CHILD WITH CONGENITAL HYPERINSULINISM LINKED TO INS-R MUTATION

Objectives: Mecasermin is recombinant human insulin-like growth factor 1 (IGF1) which is approved for the treatment of short stature in children with documented primary IGF1 deficiency. Leprechaunism, also known as Donohue syndrome, is a severe disease, secondary to a severe congenital insulin resistance, with prenatal and neonatal growth retardation, typical dysmorphic features, glycaemic dysregulation characterized by hyperinsulinemia and hyperandrogenism. These patients have a poor prognosis with death in the first year of life. Methods: We describe the case of a 3.5 years child, born at 35,4 weeks, with severe fetal growth restriction (weight 1149 gr; length: 38 cm; cranial circumference: 28 cm), typical facial features with low implant ears, low implant hairs, hypertrichosis, hypertrophic external genitalia, postnatal growth failure, and severe hyperglycaemia (327 mg/dl) alternated with hypoglycaemia (10 mg/dl) also during i.v. infusion of glucose; significant hyperinsulinism (1000 mcU/dl) with elevated C peptide levels (43,41 ng/ml), persistent hypertension (113/74 mmHg). He has consanguineous parents (cousins) and the mother underwent abortions before the baby was born. Results: A treatment with diazoxide (5 mg/kg/day) was tried with limited efficacy. He was treated with ACE-inhibitor (Captopril) at the dose of 0,02 mg/kg/day with a low response. The Captopril dose was increased at 0,04 mg/kg/day with a regulation of the blood pressure (76/54 mmHg). The genetic study of INS-R was showed a homozygote mutation in the insulin receptor (INS-R) gene. The mutation reported was c.3289C>T (CAG->TAG) p.Gln1097Stop (Q1097X). For the growth delay and the hypotrophic muscular masses he started a off-label treatment with mecasermin at increasing doses. He had no adverse events linked to the treatment. Otherwise, he improved growth and muscular strength. Conclusions: The singular case is of relieve for the rarity of the disease and for the good response to the treatment with mecasermin, the real opportunity for these children with a severe disease otherwise with a poor prognosis.