A case report of hyperinsulinemic hypoglycemia caused by a heterozygous novel mutation in the insulin receptor gene

Abstract

Introduction: Mutations in the insulin receptor (INSR) gene usually progress with insulin resistance and hyperglycemia. However, rare heterozygous INSR gene mutations that cause hyperinsulinemic hypoglycemia (HH) have also been described. A case with hyperinsulinemic hypoglycemia due to a new variant mutation in the INSR gene, is presented. Case: A 13-month-old male patient was referred to us with complaints of contractions in his entire body and low blood sugar in his history. He was born 3900 grams with spontaneous vaginal delivery as term birth. He had a similar seizure history 1 month ago. In family history; There was no consanguinity between father and mother. His father had a growth hormone treatment history and he had iris coloboma. Anthropometric measurements; Height: 78 cm (SDS: 0.24), weight: 12.1 kg (SDS: 1.08), head circumference: 45 cm (SDS: -0.37) was normal. In the physical examination of the patient, anterior fontanel was 0.5*0,5 cm open, elongated penis length was 3,5 cm, testicles were bilaterally palpable, other system examinations were normal. Laboratory values measured in hypo glycemic state (glucose: 35 mg/dL) are given in the table. In addi tion, the patient’s metabolic tests (tandem, blood amino acid, urine organic acid, ammonia) were normal.Hydrocortisone and diazoxide treatment were started simulta neously because the cortisol levels measured at the time of hypo glycemic attack were 3.9 ug/dL (low) and insulin was 7.6 uU/mL. Abdominal ultrasound was requested for the examination of pan creatic anomaly and it was found to be normal. Genetic result showed in INSR NM_000208.2 Exon 20 c.3634G>A p mutation. Anew mutation was detected in Val1212lle. During the follow-up the basal cortisol value measured was 16.2 ug/dL. After this result and genetical diagnosis, hydrocortisone treatment was discontin ued and diazoxide treatment was continued. The patient’s blood sugar is followed closely, and the follow-up continues in terms of conversion to diabetes. Conclusion: In conclusion, heterozygous INSR gene mutation causing hyper insulinemic hypoglycemia was detected in our case. This case is presented because INSR mutations are rare in the eti ology of hyperinsulinism in hypoglycemic patients and also the detected mutation is new.