ESPE Abstracts

Introduction: Rabson-Mendenhall Syndrome (RMS) is an autosomal recessive, extremely rare, serious insulin resistance syndrome that occurs as a result of mutation in the insulin receptor (INSR) gene. Pathogenic variants in the INSR gene cause a broad spectrum of inherited insulin resistance syndromes. Here, a male case who presented with the complaint of diffuse acanthosis nigricans and was diagnosed with RMS is shared.

Case Report: A 12-year-old 4-month-old male patient, who had no known disease before, applied with the complaint of darkening on the body for the last 3 years. On physical examination, his general condition was good, his body weight was 32.6 kg (-1.05 SDS), his height was 140.1 cm (-1.71 SDS), and his body mass index was 16.61 (-1.05 SDS). Puberty examination was compatible with tanner stage 3. The patient had extensive acanthosis nigricans, hyperkeratosis and hypertrichosis, more prominently in the neck, axilla, umbilical region and genital region. He had a rough face and muscular body appearance. In her family history, the patient's mother and uncles had a heavy history of type 2 diabetes, who was born from a first-degree cousin marriage. In the laboratory tests, fasting blood glucose of 68mg/dl and simultaneous fasting insulin of 227µIU/ml were found in the patient, and insulin resistance syndromes were considered. HbA1c level was measured as 6.2%. In the oral glucose tolerance test, 0hr glucose was 50mg/dl, insulin was 386.4 µIU/ml, 2hr glucose was 182, and insulin was 1000 µIU/ml. Diabetic diet was started and blood glucose was monitored. Metformin treatment was started in the patient who had hyperglycemia-hypoglycemia attacks with diet. Genetic analysis with next-generation sequencing revealed a c.3529+5G>A homozygous mutation in the INSR gene. In the in slico analysis, the mutation was evaluated as pathogenic and Rabson-Mendenhall syndrome was diagnosed. The segregation analysis of the patient continues.

Conclusion: As a result, a 12-year-old male patient with only skin darkening was diagnosed with RMS, and he is being followed up with metformin treatment because he has postprandial hyperglycemia. However, RMS patients in need of recombinant IGF-1 and high-dose insulin therapy have been reported in the literature. This shows the variability of the clinic. In this syndrome, which has no definitive treatment, preimplantation genetic analysis, genetic counseling and close follow-up of the patients are required.