Liver pathology and biochemistry in patients with mutations in TRIM37 gene (Mulibrey nanism).

BACKGROUND AND AIMS: Mulibrey nanism (MUL) is a multiorgan disease caused by recessive mutations in the TRIM37 gene. Chronic heart failure and hepatopathy are major determinants of prognosis in MUL patients, which prompted us to study liver biochemistry and pathology in a national cohort of MUL patients. METHODS: Clinical, laboratory and imaging data were collected in a cross-sectional survey and retrospectively from hospital records. Liver histology and immunohistochemistry for 10 biomarkers were assessed. RESULTS: Twenty-one MUL patients (age 1-51 years) with tumour suspicion showed moderate congestion, steatosis and fibrosis in liver biopsies and marginally elevated levels of serum GGT, AST, ALT and AST to platelet ratio index (APRI) in 20%-66%. Similarly, GGT, AST, ALT and APRI levels were moderately elevated in 12%-69% of 17 MUL patients prior to pericardiectomy. In a cross-sectional evaluation of 36 MUL outpatients, GGT, total bilirubin and galactose half-life (Gal½) correlated with age (r = 0.45, p = .017; r = 0.512, p = .007; r = 0.44, p = .03 respectively). The frequency of clearly abnormal serum values of 15 parameters analysed, however, was low even in patients with signs of restrictive cardiomyopathy. Transient elastography (TE) of the liver revealed elevated levels in 50% of patients with signs of heart failure and TE levels correlated with several biochemistry parameters. Biomarkers of fibrosis, sinusoidal capillarization and hepatocyte metaplasia showed increased expression in autopsy liver samples from 15 MUL patients. CONCLUSION: Liver disease in MUL patients was characterized by sinusoidal dilatation, steatosis and fibrosis with individual progression to cirrhosis and moderate association of histology with cardiac function, liver biochemistry and elastography.

Restriction of lung volumes but normal function of pulmonary tissue in mulibrey nanism.

BACKGROUND: Mulibrey nanism (MUL) is a rare growth restriction disorder with multiple organ manifestations caused by genetic defects affecting the TRIM37 protein. A perimyocardial heart disease is the most serious manifestation. Many MUL children appear to suffer from airway obstruction related to infection or exercise, prompting use of inhaled therapies. Asthma medication is continued up to adolescence or even to adulthood due to persisting of symptoms. The pulmonary pathophysiology has previously not been evaluated in any MUL cohort. METHODS: Thirty three finnish MUL patients (median age 20 years) were investigated with several lung function tests: spirometry with bronchodilatation test, single-breath diffusing capacity for carbon monoxide, single-breath lung volume measurements with helium dilution, and thoracic gas volume, airway resistance and specific conductance measurements with a body plethysmograph. As MUL typically affects body proportions, all variables were compared with reference values and with predicted values calculated from sitting height. RESULTS: Total lung capacity and forced vital capacity were markedly reduced (total lung capacity [TLC] and forced vital capacity [FVC], P < .001, 51%-63% of predicted) and also forced expiratory volume in the first second was reduced (FEV1; P < .001, 47%-57%). No signs of airway obstruction was seen (normal FEV1/FVC and specific airway conductance SGaw). Diffusing capacity (DLCO) was decreased (P < .001, 60%-67%) but when related to alveolar volume it was increased (DLCO/VA, P < .001, 130%-148%). Bronchodilatation suggesting active asthma (FEV1 change ≥12% and ≥​​200 mL) was found only in one patient. CONCLUSION: MUL patients typically have volume restriction of the lungs, but function of the pulmonary tissue remains intact. Evidence of asthma in lung function testing at adult age is rare.

Renal findings in patients with Mulibrey nanism.

BACKGROUND: Mulibrey nanism (MUL) is a rare inherited disease caused by genetic defects affecting peroxisomal TRIM37 protein. MUL affects multiple organs, leading to growth retardation and early onset type 2 diabetes. We aimed to characterize the structure and function of kidneys and the urinary tract in a large cohort of Finnish MUL patients. METHODS: Ultrasound, magnetic resonance imaging (MRI), and autopsy findings of the kidneys and urinary tract from 101 MUL patients were retrospectively analyzed. Renal function was examined using blood and urine biochemistry. Kidney pathology was assessed by histology and immunohistochemistry from biopsy and autopsy samples. RESULTS: Structural anomalies of the kidneys and urinary tract were found in 13 % of MUL patients and renal tumors and macroscopic cystic lesions in 14 % and 43 % respectively. Overall, kidney histology was well preserved, but glomerular cysts with a wide Bowman's space were observed in most samples (87 %). Also, prominent and abundant blood vessels with thick walls were typically seen. Expression of endothelial cell markers and angiogenic growth factors PDGF-B and FGF1 (but not VEGF-A) was significantly increased in MUL kidneys. Markers of fibrosis and epithelial-mesenchymal transformation, α-SMA, and vimentin were moderately up-regulated. Despite radiological and histological changes, most MUL patients (age 0.2-51 years) had normal kidney function. However, 9 out of 36 patients (25 %) had hypertension and 6 out of 26 (23 %) had mildly decreased glomerular filtration. CONCLUSIONS: Genetic defects in the TRIM37 gene lead to an increased risk for kidney anomalies, renal tumors, and solitary cysts in addition to glomerular cystic lesions, but not to progressive deterioration of renal function.