Insulin resistance syndrome in subjects with mutated RING finger protein TRIM37.

We evaluated the glucose and lipid metabolism in 65 patients (aged 1.1-55 years) with mulibrey (muscle-liver-brain-eye) nanism (MUL), which is a monogenic disorder with prenatal-onset growth failure and typical clinical characteristics. MUL is caused by mutations in the TRIM37 gene, encoding a peroxisomal protein (TRIM37) with E3 ubiquitin-ligase activity. The subjects underwent clinical evaluation, abdominal ultrasonography, and laboratory measurements, including a 3-h oral glucose tolerance test. The results showed a dramatic change in glucose and lipid metabolism with age in MUL subjects. While the children had low fasting glucose and insulin levels, 90% of the adults had high fasting and postload insulin values (up to 1,450 mU/l). A 10-fold decrease in the fasting glucose-to-insulin ratio and a 4-fold decrease in whole-body insulin sensitivity index were observed. Insulin resistance, fatty liver, high serum leptin, hypertension, and acantosis nigricans were already evident in many slim prepubertal children. Half of the adults had type 2 diabetes, and an additional 42% showed impaired glucose tolerance. Seventy percent fulfilled the National Cholesterol Education Program criteria for metabolic syndrome. The peroxisomal targeting and the functional link of TRIM37 to the ubiquitin-proteosome pathway may provide novel clues to the development of metabolic syndrome.