Mulibrey nanismissa ilmenevän hypogonadismin, infertiliteetin ja kasvainalttiuden tutkimus

Mulibrey nanism (MUL; OMIM 253250) is an autosomal recessive disorder belonging to the Finnish disease heritage and currently classified as a peroxisomal disorder. MUL is characterized by intrauterine-onset growth restriction, typical dysmorphic features, restrictive perimyocardial heart disease, and severe insulin resistance. The causative gene, TRIM37, is located on chromosome 17q22-q23 and encodes for a peroxisomal protein (TRIM37) with ubiquitin E3-ligase activity, suggesting its role in proteasomal protein degradation. All 19 mutations identified to date, including 4 in Finnish patients, are likely to produce a non-functioning protein. For many decades, the clinical care and follow-up of Finnish MUL patients were based at the Children s Hospital in Helsinki, generating a unique clinical experience and data set for this patient group. In follow-up, it became evident that a substantial proportion of these patients developed hypogonadism, were infertile, and had an increased risk of developing tumors. Thus, the principal focus of this study was to characterize the hypogonadism and infertility associated with this disorder, and furthermore to define the tumors and tumor predisposition in MUL, both clinically and immunohistochemically. A total of 92 Finnish patients (0.7-77 years) were included in the study; 22 post pubertal females participated in the female hypogonadism study, and 28 male patients participated in the male hypogonadism study. All hospital records were evaluated, and physical, laboratory, and radiological examinations were performed according to clinical protocols. Biopsies (taken on clinical grounds) and autopsy samples were used for histological and immunohistochemical studies. In addition, 15 freshly frozen samples from sporadic ovarian fibrothecomas were analyzed for the role of TRIM37 in the development of these tumors. All MUL patients developed hypogonadism due to a primary gonadal defect and were either infertile or severely subfertile. Women demonstrated spontaneous puberty, incomplete breast development, and early irregularity of menstrual periods with subsequent ovarian failure. Their ovaries were hypoplastic and their uteri were small. The men also experienced spontaneous puberty with somewhat small testes characterized by varying degrees of degeneration and few mature germ cells. Semen samples showed either severe oligoasthenozoospermia or azoospermia. No spontaneous pregnancies had been conceived among the MUL patients. Four men had undergone infertility treatment, which in one case was successful, resulting in the delivery of a healthy child. The MUL patients displayed a high frequency of both benign and malignant tumors especially of endocrine origin. A total of 232 tumorous lesions in several different organs were discovered in the patient cohort. Histologically, the architecture of several organs was disturbed, indicating aberrant organogenesis. One of the most frequent tumors was ovarian fibrothecomas, which are fairly uncommon in the general population, found in 55% of the female patients. The study of inherited monogenic disorders has contributed substantially to our understanding of gene function and human disease. In MUL, mutations in TRIM37 lead to failure of sexual maturation in both females and males, and fertility is seriously compromised. In addition, the patients are at a very high risk for developing benign and malignant tumors in several different organs. This study suggests a role for TRIM37 protein in the cellular functions governing gametogenesis, gonadal function, and proliferation.Mulibrey nanismi (MUL) on suomalaiseen tautiperintöön kuuluva, peittyvästi periytyvä sairaus, jolle on tyypillistä sikiöaikana alkava kasvuhäiriö, poikkeavat kasvonpiirteet, restriktiivinen sydäntauti sekä insuliiniresistenssi ja tyypin 2 diabetes. Taudin aiheuttaa mutaatiot TRIM37-geenissä kromosomissa 17q22-q23. TRIM37-proteiini paikantuu solujen peroksisomeihin, mutta sen fysiologinen tehtävä soluissa on avoin. Tutkimusaineistona oli 92:n suomalaisen 0.7-77 vuotiaan MUL-potilaan kohortti, jonka seuranta käynnistyi 1980-luvulla HYKS:in Lastenklinikassa. Tutkimuksessa selvitettiin potilaiden murrosiän kehitystä, kivesten ja munasarjojen toimintaa, fertiliteettiä sekä MUL:iin liittyvää kasvainalttiutta. Tutkimusmenetelminä käytettiin kliinisen tiedonkeruun ja seurannan ohella radiologisia tutkimuksia, laboratoriomäärityksiä sekä histologisia ja immunohistokemiallisia analyyseja. Viime mainittuihin tutkimuksiin käytettiin kliinisin indikaatioin otettuja koepaloja ja obduktioista saatuja kudosnäytteitä. Tutkimuksessa kävi ilmi, että MUL:iin liittyy sukupuolirauhasten vaurio sekä munasolu- ja siittiökato. Gonadien toiminnan heikentyminen oli kliinisesti ja sukupuolihormonimäärityksin todettavissa murrosiän kehityksen aikana tai sen jälkeen. Lisäksi potilaat olivat täysin infertiilejä tai heidän hedelmällisyytensä oli vahvasti heikentynyt. Naisilla murrosiän kehitys käynnistyi spontaanisti, mutta rintojen kehitys jäi vajaaksi ja kuukautiskierrossa ilmeni jo loppupuberteetissa epäsäännöllisyyttä, joka vaiheittain päättyi kuukautisten loppumiseen merkkinä munasarjatoiminnan ennenaikaisesta hiipumisesta. Myös MUL-poikien murrosiän kehitys käynnistyi spontaanisti ja veren sukupuolihormonipitoisuudet olivat normaalit. Kivesten koko jäi kuitenkin pieneksi ja kivesvaurion merkit näkyivät histologisesti vaihtelevanasteisena degeneraationa ja sukusolujen niukkuutena. Murrosiän jälkeen kivesvaurio oli todettavissa myös hormonimäärityksin. Siemennestenäytteissä ei ollut lainkaan siittiöitä tai niiden määrä oli vahvasti alentunut. MUL-potilailla ei ole esiintynyt spontaaneja raskauksia. Neljä miestä on toistaiseksi osallistunut hedelmöityshoitoihin, joista yhdessä tapauksessa hoito on päättynyt terveeseen lapseen. MUL-potilailla esiintyi runsaasti sekä hyvänlaatuisa kasvaimia että syöpää. Vajaalla sadalla potilaalla todettiin yhteensä 232 tuumoriksi luokiteltavaa muutosta useassa eri elimessä. Monissa sisäelimissä oli havaittavissa myös kehityshäiriöitä. Yksi tavallisimpia kasvaimia oli harvinainen munasarjojen fibrotekooma, jota tavattiin 55%:lla MUL-naisista. Tutkimus osoittaa, että MUL:iin liittyy sekä nais- että miespuolinen hedelmättömyys. Sairaudessa on myös selvät syöpäoireyhtymän piirteet. Tulokset viittaavat siihen, että TRIM37-proteiinilla on merkitystä sukupuolirauhasten kehityksessä ja toiminnassa, samoin kuin normaalissa organogeneesissä ja syövän synnyssä. Harvinaisuudestaan huolimatta MUL voikin toimia yleisten lääketieteellisten ongelmien, kuten lapsettomuuden ja syövän synnyn kliinisenä ja solutason mallina

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 (Gal1/2) 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.Peer reviewe

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 = 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.Peer reviewe

Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism

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 wildtype. 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.Peer reviewe

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, a-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.Peer reviewe