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.

Premature ovarian insufficiency and early depletion of the ovarian reserve in the monogenic Mulibrey nanism disorder.

STUDY QUESTION: What is the timing of onset and clinical course of premature ovarian insufficiency (POI) in patients with Mulibrey nanism (MUL), a monogenic disorder caused by mutations of the peroxisomal TRIM37 gene? SUMMARY ANSWER: The number of ovarian follicles is highly reduced already in infant and young MUL girls and the majority of them will have early depletion of follicles resulting in clinical and biochemical signs of POI. WHAT IS KNOWN ALREADY: Both female and male patients with MUL show failure of sexual maturation, signs of hypogonadism and infertility. STUDY DESIGN, SIZE, DURATION: We studied the gonadal function, pubertal development and ovarian reserve in 33 MUL patients aged 5.1-47.3 years (median age 22.3) at the end of observation. The patients were followed between 2004 and 2014 and 19 pubertal or postpubertal patients were enrolled in a cross-sectional study. PARTICIPANTS/MATERIALS, SETTING, METHODS: The period of postnatal activation of the hypothalamic-pituitary-gonadal axis (minipuberty), pubertal development and menstrual history were assessed longitudinally. The cross-sectional study included gynecological examination, analysis of reproductive hormones and ultrasonography with evaluation of ovarian volume and antral follicle count. MAIN RESULTS AND THE ROLE OF CHANCE: Infant girls experienced a transient minipuberty with a high FSH surge. In childhood, gonadotropins were normal or slightly elevated but began to rise to hypergonadotropic levels in prepuberty. Anti-Müllerian hormone (AMH) levels remained undetectable or low throughout childhood. The onset of puberty occurred spontaneously and the median age at menarche was 12.5 years. Of the patients, 54% never attained regular menses and 10 years from menarche, only 8% of the women menstruated regularly. In the cross-sectional study, none of the patients had normal ovarian morphology under ultrasonography. Ovaries were hypoplastic and 82% had no or fewer than two visible antral follicles. AMH levels were undetectable in the vast majority (89%). LIMITATIONS, REASONS FOR CAUTION: The Finnish MUL patients genotypically form a homogenous group and therefore it is possible, that different TRIM37 mutations lead to different hypogonadal phenotypes. However, to date there is no known genotype-phenotype correlation in MUL. WIDER IMPLICATIONS OF THE FINDINGS: In MUL, AMH is a useful marker of ovarian function. MUL should be added to the list of syndromes associated with POI and correspondingly, TRIM37 should be added to the list of genes associated with POI. To our knowledge, TRIM37 is the first known gene coding for a peroxisomal membrane protein associated with female gonadal failure and infertility. Elucidating the role of syndromic genes in reproduction may aid in a greater understanding of ovarian biology. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by the Finnish Foundation for Pediatric Research, Finska Läkaresällskapet, the Sigrid Jusélius Foundation and Helsinki University Hospital Research Funds. The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: Not applicable.

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.

[Update on Current Care guidelines: obesity (children)]. / Käypä hoito -suosituksen päivitystiivistelmä: Lihavuus (lapset).

Childhood obesity is an increasing health problem. There may be possibilities to prevent obesity in childhood, and efficient interventions to treat obese children have been published. Local and regional strategies to prevent and to treat childhood obesity are needed.

Pericardial Constriction and Myocardial Restriction in Pediatric Mulibrey Nanism: A Complex Disease With Diastolic Dysfunction.

BACKGROUND: Mulibrey nanism (MUL) is a rare condition with profound growth delay. Congestive heart failure is a major determinant of prognosis. The aim was to delineate pericardial constriction and myocardial functional abnormalities in a pediatric MUL sample. METHODS: A total of 23 MUL patients and 23 individually sex- and age-matched healthy control subjects were prospectively assessed in a cross-sectional study with echocardiography. RESULTS: Clinical signs of heart failure were present in 7 MUL patients, with severe congestive heart failure in 2. Significant diastolic dysfunction, mainly related to constriction, was found in MUL patients without pericardiectomy (N = 18)-septal bounce, pronounced hepatic vein atrial reversal and right heart inflow-outflow variations, and decreased inferior vena cava collapse during respiration. The appearance of the pericardium was not different from that of control subjects. Longitudinal diastolic myocardial velocities were similar to those in control subjects, suggesting an absence of significant myocardial restriction. Right ventricular free wall longitudinal systolic strain and bilateral longitudinal myocardial systolic velocities were decreased in MUL patients, indicating mild biventricular systolic dysfunction. Myocardial motion abnormalities and persistent congestive heart failure were common (in 3 of 6) in MUL patients with a history of pericardiectomy. Cardiac dimensions were similar between MUL patients and control subjects when adjusting for body size, except for smaller biventricular volumes. CONCLUSIONS: MUL disease presents with significant constriction-related diastolic dysfunction and mild bilateral systolic dysfunction. Constriction-restriction assessments during follow-up could be of benefit in decision-making regarding pericardiectomy in MUL disease. Myocardial abnormalities were prevalent among MUL patients who had undergone pericardiectomy and are consistent with progression of myocardial disease in a significant proportion of patients.

CONTEXTE: Le nanisme Mulibrey (MUL) est une maladie rare qui donne lieu à un retard de croissance marqué. L'insuffisance cardiaque congestive est un déterminant majeur du pronostic. L'objectif de cette étude était de caractériser la constriction péricardique et les anomalies fonctionnelles myocardiques dans un échantillon de cas de MUL pédiatrique. MÉTHODOLOGIE: Au total, 23 patients atteints de MUL et 23 sujets témoins en bonne santé ont été appariés individuellement selon le sexe et l'âge et soumis à une évaluation prospective dans le cadre d'une étude transversale avec échocardiographie. RÉSULTATS: Sept patients atteints de MUL présentaient des signes cliniques d'insuffisance cardiaque, et deux, une insuffisance cardiaque congestive sévère. Une dysfonction diastolique significative, principalement liée à la constriction, a été observée chez les patients atteints de MUL n'ayant pas subi de péricardiectomie (N = 18) ­ rebond septal, inversion auriculaire marquée du flux de la veine hépatique, variations prononcées du flux entrant et sortant du cœur droit, diminution du collapsus de la veine cave inférieure pendant la respiration. L'apparence du péricarde n'était pas différente de celle notée chez les sujets témoins. Les vélocités myocardiques longitudinales pendant la diastole étaient similaires à celles relevées chez les sujets témoins, ce qui suggère l'absence de restriction myocardique significative. La déformation longitudinale de la paroi libre du ventricule droit et les vélocités myocardiques longitudinales bilatérales étaient diminuées pendant la systole chez les patients atteints de MUL, ce qui indique une dysfonction systolique biventriculaire légère. Les anomalies de la cinétique myocardique et la persistance de l'insuffisance cardiaque congestive étaient fréquentes (dans trois cas sur six) chez les patients atteints de MUL ayant des antécédents de péricardiectomie. Les dimensions cardiaques chez les patients atteints de MUL étaient similaires à celles observées chez les sujets témoins après les ajustements en fonction de la taille corporelle, à l'exception des volumes biventriculaires, qui étaient plus petits. CONCLUSIONS: Le MUL entraîne une dysfonction diastolique significative liée à la constriction et une légère dysfonction systolique bilatérale. Les évaluations axées sur la constriction et la restriction effectuées au cours du suivi pourraient être utiles pour la prise de décisions concernant le recours à la péricardiectomie dans les cas de MUL. Les anomalies myocardiques étaient fréquentes chez les patients atteints de MUL qui avaient subi une péricardiectomie et concordent avec la progression de la myocardiopathie dans une proportion significative de cas.

Case report: A novel de novo IGF2 missense variant in a Finnish patient with Silver-Russell syndrome.

Silver-Russell syndrome (SRS, OMIM 180860) is a rare imprinting disorder characterized by intrauterine and postnatal growth restriction, feeding difficulties in early childhood, characteristic facial features, and body asymmetry. The molecular cause most commonly relates to hypomethylation of the imprinted 11p15.5 IGF2/H19 domain but remains unknown in about 40% of the patients. Recently, heterozygous paternally inherited pathogenic variants in IGF2, the gene encoding insulin-like growth factor 2 (IGF2), have been identified in patients with SRS. We report a novel de novo missense variant in IGF2 (c.122T > G, p.Leu41Arg) on the paternally derived allele in a 16-year-old boy with a clinical diagnosis of SRS. The missense variant was identified by targeted exome sequencing and predicted pathogenic by multiple in silico tools. It affects a highly conserved residue on a domain that is important for binding of other molecules. Our finding expands the spectrum of disease-causing variants in IGF2. Targeted exome sequencing is a useful diagnostic tool in patients with negative results of common diagnostic tests for SRS.

Submicroscopic genomic alterations in Silver-Russell syndrome and Silver-Russell-like patients.

BACKGROUND: Silver-Russell syndrome (SRS, OMIM 180860) features fetal and postnatal growth restriction and variable dysmorphisms. Genetic and epigenetic aberrations on chromosomes 7 and 11 are commonly found in SRS. However, a large fraction of SRS cases remain with unknown genetic aetiology. METHODS: 22 patients with a diagnosis of SRS (10 with H19 hypomethylation and 12 of unknown molecular aetiology) and their parents were studied with the Affymetrix 250K Sty microarray. Several analytical approaches were used to identify genomic aberrations such as copy number changes (CNCs), loss of heterozygosity (LOH) and uniparental disomy (UPD). Selected CNCs were verified with quantitative real-time PCR. RESULTS: The largest unambiguous CNCs were found in patients with previously molecularly unexplained SRS with relatively mild phenotypes: a heterozygous deletion of chromosome 15q26.3 including the IGF1R gene (2.6 Mb), an atypical distal 22q11.2 deletion (1.1 Mb), and a pseudoautosomal region duplication (2.7 Mb) in a male patient. LOH regions of potential relevance to the SRS phenotype were also identified. Importantly, no duplications or UPD of chromosomes 7 or 11 were identified. CONCLUSION: Unexpected submicroscopic genomic events with pathogenic potential were found in three patients with molecularly unexplained SRS that was mild. The findings emphasise that SRS is heterogeneous in genetic aetiology beyond the major groups of H19 hypomethylation and maternal UPD7 and that unbiased genome-scale screens may reveal novel genotype-phenotype correlations.

TRIM37 prevents formation of centriolar protein assemblies by regulating Centrobin.

TRIM37 is an E3 ubiquitin ligase mutated in Mulibrey nanism, a disease with impaired organ growth and increased tumor formation. TRIM37 depletion from tissue culture cells results in supernumerary foci bearing the centriolar protein Centrin. Here, we characterize these centriolar protein assemblies (Cenpas) to uncover the mechanism of action of TRIM37. We find that an atypical de novo assembly pathway can generate Cenpas that act as microtubule-organizing centers (MTOCs), including in Mulibrey patient cells. Correlative light electron microscopy reveals that Cenpas are centriole-related or electron-dense structures with stripes. TRIM37 regulates the stability and solubility of Centrobin, which accumulates in elongated entities resembling the striped electron dense structures upon TRIM37 depletion. Furthermore, Cenpas formation upon TRIM37 depletion requires PLK4, as well as two parallel pathways relying respectively on Centrobin and PLK1. Overall, our work uncovers how TRIM37 prevents Cenpas formation, which would otherwise threaten genome integrity.

High frequency of tumours in Mulibrey nanism.

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.

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.

Rare Variants in Genes Linked to Appetite Control and Hypothalamic Development in Early-Onset Severe Obesity.

Context: The hypothalamic circuit has an essential role in the regulation of appetite and energy expenditure. Pathogenic variants in genes involved in the hypothalamic leptin-melanocortin pathway, including melanocortin-4-receptor (MC4R), have been associated with monogenic obesity. Objective: To determine the rate and spectrum of rare variants in genes involved in melanocortin pathway or hypothalamic development in patients with severe early-onset obesity (height-adjusted weight >60% before age 10 years). Methods: We used a custom-made targeted exome sequencing panel to assess peripheral blood DNA samples for rare (minor allele frequency <0.5%), pathogenic/likely pathogenic variants in 24 genes related to the hypothalamic circuit in 92 subjects (51% males, median age 13.7 years) with early-onset severe obesity (median body mass index (BMI) Z-score + 4.0). Results: We identified a novel frameshift deletion in MC4R (p.V103Afs5*) in two unrelated patients and a previously reported MC4R variant (p.T112M) in one patient. In addition, we identified rare heterozygous missense variants in ADCY3 (p.G1110R), MYT1L (p.R807Q), ISL1 (p.I347F), LRP2 (p.R2479I, and p.N3315S) and a hemizygous missense variant in GRPR (p.L87M) (each in one patient), possibly contributing to the obesity phenotype in these patients. Altogether 8 % (7/92) of the subjects had rare pathogenic/likely pathogenic variants in the studied genes. Conclusions: Rare genetic variants within the hypothalamic circuit are prevalent and contribute to the development of severe early-onset obesity. Targeted exome sequencing is useful in identifying affected subjects. Further studies are needed to evaluate the variants' clinical significance and to define optimal treatment.

Clinically distinct epigenetic subgroups in Silver-Russell syndrome: the degree of H19 hypomethylation associates with phenotype severity and genital and skeletal anomalies.

CONTEXT: The H19 imprinting control region (ICR), located on chromosome 11p15.5, has been reported hypomethylated in 20-65% of Silver-Russell syndrome (SRS) patients. OBJECTIVE: We investigated the methylation status of 11p15.5 ICRs in SRS patients and children born small for gestational age (SGA) to clarify the relationship between phenotype and H19 methylation status. METHODS: We performed methylation screens of the H19 and KCNQ1OT1 ICRs in 42 SRS patients, including seven maternal uniparental disomy of chromosome 7 patients, and 90 SGA children without SRS. Clinical data were evaluated from patient records, and seven hypomethylated patients were clinically and radiologically reexamined. RESULTS: H19 ICR hypomethylation was found in 62% of SRS patients but in no SGA children. A clinical severity score demonstrated strong correlation between hypomethylation level and phenotype severity. Hypomethylation related to a more severe SRS phenotype, in which especially asymmetry and micrognathia were significantly more common. Extremely hypomethylated patients had abnormally high lumbar vertebrae, lumbar hypomobility, elbow subluxations, and distinct hand and foot anomalies. They also presented with congenital aplasia of the uterus and upper vagina, equivalent to the Mayer-Rokitansky-Küster-Hauser syndrome in females, and cryptorchidism and testicular agenesis in males. CONCLUSIONS: We found a dose-response relationship between the degree of H19 hypomethylation and phenotype severity in SRS. We report for the first time the association of specific anomalies of the spine, elbows, hands and feet, and genital defects in SRS with severe H19 hypomethylation. Classical SRS features were found in H19 hypomethylation and milder symptoms in maternal uniparental disomy of chromosome 7, thus distinguishing two separate clinical and etiological subgroups.

Gynecological tumors in Mulibrey nanism and role for RING finger protein TRIM37 in the pathogenesis of ovarian fibrothecomas.

Mulibrey nanism is an autosomal recessive growth disorder caused by mutations in the TRIM37 gene encoding a protein of unknown function. More than half of female patients with Mulibrey nanism develop benign mesenchymal tumors of ovarian sex cord-stromal origin. In this work, we characterize the gynecological tumors of female patients with Mulibrey nanism in detail. In addition to tumors of the fibrothecoma group, 18% (4/22) of the patients were observed with epithelial neoplasias, including 2 ovarian adenofibromas, 1 ovarian poorly differentiated adenocarcinoma and 1 endometrial adenocarcinoma. To investigate the possible involvement of TRIM37 alterations in the pathogenesis of sporadic fibrothecomas, we analyzed the TRIM37 cDNA for mutations and alternatively spliced transcripts and TRIM37 expression in fibrothecomas of women without Mulibrey nanism. No mutations in the open-reading frame of TRIM37 were detected. Two alternatively spliced variants were found, one lacking exon 23 and one exon 2. TRIM37del2 was also found in normal ovary but in a proportion of sporadic fibrothecomas, the TRIM37del2:TRIM37 ratio was increased. In normal ovary, TRIM37 was localized in the cytoplasm of stromal cells, especially theca cells surrounding developing follicles. TRIM37 transcript was found in all sporadic fibrothecomas examined, but 80% (20/25) of the tumors showed reduced or absent expression of TRIM37 protein. Allelic loss at the TRIM37 locus (17q22-23) was observed in 6% of sporadic fibrothecomas. Nearly half of the sporadic fibrothecomas showed evidence of CpG promoter methylation, suggesting promoter downregulation as one mechanism of reduced TRIM37 expression. In conclusion, inherited biallelic inactivation of TRIM37 (Mulibrey nanism) predisposes to both mesenchymal and epithelial ovarian tumors and dysregulation of TRIM37 may also be involved in the pathogenesis of sporadic fibrothecomas.

Testicular Function and Bone in Young Men with Severe Childhood-Onset Obesity.

BACKGROUND: Previous studies suggest increased risk for hypoandrogenism and fractures in men with obesity. We aimed to describe the effects of severe childhood-onset obesity on the cross talk between metabolic state, testes, and skeleton at late puberty. METHODS: A cohort of adolescent and young adult males with severe childhood-onset obesity (n = 21, mean age 18.5 years) and an age-matched control group were assessed for testicular hormones and X-ray absorptiometry-derived bone mass. RESULTS: Current median body mass indexes for the obese and control subjects were 37.4 and 22.9. Severe early-onset obesity manifested with lower free testosterone (median [interquartile range] 244 [194-332] vs. 403 [293-463] pmol/L, p = 0.002). Lower insulin-like 3 (1.02 [0.82-1.23] vs. 1.22 [1.01-1.46] ng/mL, p = 0.045) and lower ratio of testosterone to luteinizing hormone (2.81 [1.96-3.98] vs. 4.10 [3.03-5.83] nmol/IU, p = 0.008) suggested disrupted Leydig cell function. The degree of current obesity inversely correlated with free testosterone (τ = -0.516, p = 0.003), which in turn correlated positively with bone area at all measurement sites in males with childhood-onset obesity. CONCLUSIONS: Severe childhood-onset obesity is associated with impaired Leydig cell function in young men and lower free testosterone may contribute to impaired skeletal characteristics.

Hypomethylation of HOXA4 promoter is common in Silver-Russell syndrome and growth restriction and associates with stature in healthy children.

Silver-Russell syndrome (SRS) is a growth retardation syndrome in which loss of methylation on chromosome 11p15 (11p15 LOM) and maternal uniparental disomy for chromosome 7 [UPD(7)mat] explain 20-60% and 10% of the syndrome, respectively. To search for a molecular cause for the remaining SRS cases, and to find a possible common epigenetic change, we studied DNA methylation pattern of more than 450 000 CpG sites in 44 SRS patients. Common to all three SRS subgroups, we found a hypomethylated region at the promoter region of HOXA4 in 55% of the patients. We then tested 39 patients with severe growth restriction of unknown etiology, and found hypomethylation of HOXA4 in 44% of the patients. Finally, we found that methylation at multiple CpG sites in the HOXA4 promoter region was associated with height in a cohort of 227 healthy children, suggesting that HOXA4 may play a role in regulating human growth by epigenetic mechanisms.

Two missense mutations in KCNQ1 cause pituitary hormone deficiency and maternally inherited gingival fibromatosis.

Familial growth hormone deficiency provides an opportunity to identify new genetic causes of short stature. Here we combine linkage analysis with whole-genome resequencing in patients with growth hormone deficiency and maternally inherited gingival fibromatosis. We report that patients from three unrelated families harbor either of two missense mutations, c.347G>T p.(Arg116Leu) or c.1106C>T p.(Pro369Leu), in KCNQ1, a gene previously implicated in the long QT interval syndrome. Kcnq1 is expressed in hypothalamic GHRH neurons and pituitary somatotropes. Co-expressing KCNQ1 with the KCNE2 ß-subunit shows that both KCNQ1 mutants increase current levels in patch clamp analyses and are associated with reduced pituitary hormone secretion from AtT-20 cells. In conclusion, our results reveal a role for the KCNQ1 potassium channel in the regulation of human growth, and show that growth hormone deficiency associated with maternally inherited gingival fibromatosis is an allelic disorder with cardiac arrhythmia syndromes caused by KCNQ1 mutations.

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.

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 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.

Mulibrey heart disease: clinical manifestations, long-term course, and results of pericardiectomy in a series of 49 patients born before 1985.

BACKGROUND: Mulibrey nanism is a rare inherited disease characterized by growth failure and multiorgan manifestations, including constrictive pericarditis. Its long-term course, the results of pericardiectomy, and the details of myocardial involvement have not been reported previously. METHODS AND RESULTS: We studied 49 patients (26 men) born before 1985 and followed for up to 25 years. By 1999, 25 patients (51%) had developed congestive heart failure (CHF), 19 (39%) had undergone pericardiectomy for constrictive pericarditis, 10 (22%) had died of cardiac causes, and 5 (10%) had died of noncardiac causes. Of the 19 pericardiectomized patients, 12 derived lasting clinical benefit, whereas 1 patient suffered an early noncardiac death and 6 died later of unrelieved or recurrent CHF. At echocardiography in 34 living patients, left ventricular mass adjusted for body height and weight averaged (+/-SEM) 149+/-5 g in 21 unoperated patients, 144+/-8 g in 13 pericardiectomized patients, and 104+/-7 g in 16 healthy persons matched for age and sex (P=0.000). Autopsies of 11 patients showed fibrotic thickening of the pericardial leaves with myocardial hypertrophy and variable but mostly mild myocardial fibrosis. Endocardial thickening was seen in 3 patients. CONCLUSIONS: Constrictive pericarditis, myocardial hypertrophy, and variable myocardial fibrosis constitute the main elements of Mulibrey heart disease. At least one half of patients ultimately develop CHF. Pericardiectomy generally provides clinical benefit, but in approximately one third of patients, CHF may recur because of coexisting myocardial involvement.

Low Copy Number of the AMY1 Locus Is Associated with Early-Onset Female Obesity in Finland.

BACKGROUND: The salivary α-amylase locus (AMY1) is located in a highly polymorphic multi allelic copy number variable chromosomal region. A recent report identified an association between AMY1 copy numbers and BMI in common obesity. The present study investigated the relationship between AMY1 copy number, BMI and serum amylase in childhood-onset obesity. PATIENTS: Sixty-one subjects with a history of childhood-onset obesity (mean age 19.1 years, 54% males) and 71 matched controls (19.8 yrs, 45% males) were included. All anthropometric measures were greater in the obese; their mean BMI was 40 kg/m2 (range 25-62 kg/m2) compared with 23 kg/m2 in the controls (15-32 kg/m2). RESULTS: Mean AMY1 copy numbers did not differ between the obese and control subjects, but gender differences were observed; obese men showed the highest and obese women the lowest number of AMY1 copies (p=0.045). Further, only in affected females, AMY1 copy number correlated significantly with whole body fat percent (r=-0.512, p=0.013) and BMI (r=-0.416, p=0.025). Finally, a clear linear association between AMY1 copy number and serum salivary amylase was observed in all subgroups but again differences existed between obese males and females. CONCLUSIONS: In conclusion, our findings suggest that AMY1 copy number differences play a role in childhood-onset obesity but the effect differs between males and females. Further studies in larger cohorts are needed to confirm these observations.