A New Heterozygous Variant of c.1225_1227delTTC (p.Phe409del) in Insulin Receptor Gene Associated with Severe Insulin Resistance and Hyperandrogenemia in an Adolescent Female with Type A Severe Insulin Resistance Syndrome.

Background: Functional defects caused by mutations in the insulin receptor (INSR) gene often lead to severe hereditary insulin resistance syndromes, including but not limited to type A insulin resistance syndrome.

Method and result: Here, we report a case of a 12-year-old girl with elevated fasting blood glucose detected by opportunistic testing, associated with severe insulin resistance and hyperandrogenemia. She had axillary hair, acne, clitoral hypertrophy, prominent labia minora hypertrophy and thickened voice with BMI 20.57kg/m², and ultrasound imaging showed that she had multiple follicles in both ovaries. Insulin was initially administered, but the glycemic control was poor. Accordingly, the prescription was later switched to metformin, maintaining euglycemic blood glucose level. The whole exome sequencing from peripheral blood revealed that the patient carries NM_000208.2:c.1225_1227delTTC (p.Phe409del) heterozygous mutation in the INSR gene. She was tentatively diagnosed as type A insulin resistance syndrome based on her clinical features and heterozygous mutation in the INSR gene.

Conclusion: Our results demonstrated that type A insulin resistance syndrome in patients presenting with severe insulin resistance and hyperandrogenemia was associated with a heterozygous variant of c.1225_1227delTTC (p.Phe409del), suggesting that exon sequencing would be beneficial to detect the potential mutations in the INSR gene of these patients for precise diagnosis and intervention in clinical practice.