Monogenic diabetes due to an INSR mutation in a child with severe insulin resistance

Summary We report a case of an 11-year-old girl presenting with a new diagnosis of diabetes associated with a heterozygous missense mutation in the insulin receptor (INSR) gene. This case highlights that INSR gene variants can be a cause for monogenic diabetes in children and adolescents and the need for genetic evaluation in atypical presentations of diabetes. We also describe the possible role of metformin in treating individuals with type A insulin resistance syndrome due to INSR gene variants. Learning points Insulin receptor (INSR) gene variants can be a cause of monogenic diabetes in children and adolescents. Genetic evaluation should be considered in children and adolescents with type 2 diabetes (T2D), particularly where there is an atypical presentation and/or positive family history. Metformin may have a role in the treatment of type A insulin resistance syndrome due to heterozygous mutation of the INSR gene.

A New Mutation of the INSR Gene in a 13-Year-Old Girl with Severe Insulin Resistance Syndrome in China

Background. Mutations in insulin receptor genes can cause severe insulin resistance syndrome. Compared with Rabson-Mendenhall Syndrome and Donohue’s Syndrome, type A insulin resistance syndrome is generally not serious. The main manifestations in woman with type A insulin resistance syndrome are hyperinsulinemia, insulin resistance, acanthosis nigricans, hyperandrogenism, and polycystic ovary. Case Presentation. A 13-year-old girl (Han nationality) visited the hospital due to hairiness and acanthosis nigricans. Further examination revealed severe hyperinsulinemia, insulin resistance, elevated blood glucose, hyperandrogenism, and polycystic ovary. Analysis of the insulin receptor gene by sequencing showed the presence of a nucleotide change in intron 7 (c. 1610+1G > A). The mutation was a splicing mutation, which can obviously affect the mRNA splicing of the insulin receptor and cause its function loss. The patient was finally diagnosed with type A insulin resistance syndrome. After 2 months of metformin treatment, the patient had spontaneous menstrual cramps and significantly improved acanthosis nigricans and sex hormones. Conclusion. We report for the first time a new splicing mutation on the insulin receptor gene at the 7th intron (c.1610+1G > A), which leads to type A insulin resistance syndrome. In clinically suspected patients with polycystic ovary syndrome, if there are extremely high blood levels of insulin in the blood, genetic testing should be performed to detect insulin receptor gene mutation of type A insulin resistance syndrome.

Type A insulin resistance syndrome misdiagnosed as polycystic ovary syndrome: a case report

Background Type A insulin resistance syndrome, one type of the hereditary insulin resistance syndromes, is a rare disorder. Patients with type A insulin resistance syndrome are nonobese and demonstrate severe hyperinsulinemia, hyperandrogenism, and acanthosis nigricans. The clinical features are more severe in affected females than in males, and they mostly become apparent at the age of puberty. In many cases, when severe insulin resistance is covered up by other signs or symptoms of type A insulin resistance syndrome, patients are often easily misdiagnosed with other diseases, such as polycystic ovary syndrome. Case presentation Our patient was a 27-year-old Han Chinese woman who sought treatment because of a menstrual disorder and hirsutism. Tests showed that her levels of insulin and testosterone were elevated, and gynecological color Doppler ultrasound suggested multiple cystic changes in the bilateral ovaries. After a diagnosis of polycystic ovary syndrome was made, pulsatile gonadotropin-releasing hormone therapy and metformin were administered, but the patient’s symptoms did not improve in 1 year of follow-up. Considering that the previous diagnosis might have been incorrect, venous blood samples were collected from the patient and her relatives for genetic analysis. Subsequently, using Illumina sequencing, it was found that the proband, her father, and two brothers all had the c.3601C>T heterozygous missense mutation in exon 20 of the insulin receptor gene. The diagnosis was corrected to type A insulin resistance syndrome, and the patient’s treatment was modified. Conclusion We report a case of a young woman with type A insulin resistance syndrome that was misdiagnosed as polycystic ovary syndrome. We discuss the causes, clinical features, diagnosis, and treatment of type A insulin resistance syndrome to improve the recognition of the disease and reduce its misdiagnosis. Female patients with high androgen levels and severe hyperinsulinemia should be considered for the possibility of hereditary insulin resistance syndromes (such as type A insulin resistance syndrome). Gene sequencing helps in making an early diagnosis and developing a targeted treatment strategy.