No abstract

Mulibrey nanism (MUL) is a monogenic disorder with prenatal-onset growth failure, typical clinical characteristics, cardiopathy and tendency for a metabolic syndrome. It is caused by recessive mutations in the TRIM37 gene encoding for the peroxisomal TRIM37 protein with ubiquitin-ligase activity. In this work, the frequency and pathology of malignant and benign tumours were analysed in a national cohort of 89 Finnish MUL patients aged 0.7-76 years. The subjects had a clinical and radiological evaluation, and histological and immunohistocemical analyses on specimens obtained from biopsy, surgery or autopsy, were performed. The results show that the MUL patients have disturbed architecture with ectopic tissues and a high frequency of both benign and malignant tumours detectable in several internal organs. A total of 210 tumorous lesions were detected in 66/89 patients (74%). Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL). Tumours detected by radiology in the liver and other organs mainly comprised strongly dilated blood vessels (peliosis), vascularized cysts and nodular lesions. The lesions showed strong expression of the endothelial cell markers CD34 and CD31 as well as the myocyte marker alpha-smooth muscle actin (alpha-SMA). Our findings show that MUL is associated with frequent malignant tumours and benign adenomatous and vascular lesions, as well as disturbed organ development.

We evaluated the glucose and lipid metabolism in 65 patients (aged 1.1-55 years) with mulibrey (muscle-liverbrain-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. Diabetes 54: [3577][3578][3579][3580][3581] 2005

Mulibrey nanism (MUL) is a rare autosomal recessive multi-organ disorder characterized by severe prenatal-onset growth failure, infertility, cardiopathy, risk for tumors, fatty liver, and type 2 diabetes. MUL is caused by loss-of-function mutations in TRIM37, which encodes an E3 ubiquitin ligase belonging to the tripartite motif (TRIM) protein family and having both peroxisomal and nuclear localization. We describe a congenic Trim37 knock-out mouse (Trim37−/−) model for MUL. Trim37−/− mice were viable and had normal weight development until approximately 12 months of age, after which they started to manifest increasing problems in wellbeing and weight loss. Assessment of skeletal parameters with computer tomography revealed significantly smaller skull size, but no difference in the lengths of long bones in Trim37−/− mice as compared with wild-type. Both male and female Trim37−/− mice were infertile, the gonads showing germ cell aplasia, hilus and Leydig cell hyperplasia and accumulation of lipids in and around Leydig cells. Male Trim37−/− mice had elevated levels of follicle-stimulating and luteinizing hormones, but maintained normal levels of testosterone. Six-month-old Trim37−/− mice had elevated fasting blood glucose and low fasting serum insulin levels. At 1.5 years Trim37−/− mice showed non-compaction cardiomyopathy, hepatomegaly, fatty liver and various tumors. The amount and morphology of liver peroxisomes seemed normal in Trim37−/− mice. The most consistently seen phenotypes in Trim37−/− mice were infertility and the associated hormonal findings, whereas there was more variability in the other phenotypes observed. Trim37−/− mice recapitulate several features of the human MUL disease and thus provide a good model to study disease pathogenesis related to TRIM37 deficiency, including infertility, non-alcoholic fatty liver disease, cardiomyopathy and tumorigenesis.