Screening for rare variants in the PNPLA3 gene in obese liver biopsy patients.

Background: Previous research has clearly implicated the PNPLA3 gene in the etiology of nonalcoholic fatty liver disease as a polymorphism in the gene was found to be robustly associated to the disease. However, data on the involvement of rare PNPLA3 variants in the development of nonalcoholic fatty liver disease (NAFLD) is currently limited. Therefore, we performed an extensive mutation analysis study on a cohort of obese liver biopsy patients to determine PNPLA3 variation and its correlation with fatty liver disease.

Investigation of common and rare genetic variation in the BAMBI genomic region in light of human obesity.

The aim of this study was to confirm the previously identified link between BAMBI and human obesity by means of a genetic and functional analysis. We performed both a mutation analysis, using high-resolution melting curve analysis, and a genetic association study, including 8 common tagSNPs in the BAMBI gene region. Three of the identified genetic variants (R151W, H201R, and C229R) were evaluated for their Wnt signaling enhancing capacity in a Wnt luciferase reporter assay.

No mutations in the serotonin related TPH1 and HTR1B genes in patients with monogenic sclerosing bone disorders.

Since the identification of LRP5 as the causative gene for the osteoporosis pseudoglioma syndrome (OPPG) as well as the high bone mass (HBM) phenotype, LRP5 and the Wnt/β-catenin signaling have been extensively studied for their role in the differentiation and proliferation of osteoblasts, in the apoptosis of osteoblasts and osteocytes and in the response of bone to mechanical loading. However, more recently the direct effect of LRP5 on osteoblasts and bone formation has been questioned. Gene expression studies showed that mice lacking lrp5 have increased expression of tph1, the rate limiting enzyme for the production of serotonin in the gut.

A common LRP4 haplotype is associated with bone mineral density and hip geometry in men-data from the Odense Androgen Study (OAS).

Osteoporosis is a common disease characterized by an increased susceptibility to fracture. It is a complex disorder resulting from the interaction of several polymorphisms in different genes and environmental factors. Since we recently reported a role for low density lipoprotein-related protein (LRP)-4 in monogenic disorders with bone overgrowth, we now wanted to evaluate whether genetic variation in the LRP4 gene has an effect on the susceptibility to osteoporosis in a population based cohort from the Odense Androgen Study.

Identification of mutations in the NUCB2/nesfatin gene in children with severe obesity.

Nesfatin-1 is the N-terminal fragment of nucleobindin-2 (NUCB2) that was identified as a novel satiety molecule in rodents. The protein is reported to exert anorexigenic effects and appears to play an important role in hypothalamic pathways regulating energy homeostasis and food intake. In this study, we hypothesized that mutations in the nesfatin encoding gene NUCB2 might cause obesity in humans.

Association study of polymorphisms in the SOST gene region and parameters of bone strength and body composition in both young and elderly men: data from the Odense Androgen Study.

By means of different genetic association studies the SOST gene, encoding sclerostin, has repeatedly been suggested to regulate bone mineral density (BMD) and osteoporosis susceptibility. This study aimed at a further understanding of the importance of two previously studied single-nucleotide polymorphisms in the SOST gene, rs10534024 (SRP3) and rs9902563 (SRP9), in the Odense Androgen Study (OAS) cohort. This cohort includes a total of 1,383 Danish men from two different age groups, 20-29 years (n = 783) and 60-74 years (n = 600), and is well characterized.

Indications for a genetic association of a VCP polymorphism with the pathogenesis of sporadic Paget's disease of bone, but not for TNFSF11 (RANKL) and IL-6 polymorphisms.

Paget's disease of bone (PDB) is, after osteoporosis, the second most common metabolic bone disorder in the elderly Caucasian population. Mutations in the sequestosome 1 gene (SQSTM1) are responsible for the etiology of PDB in a subset of patients, but the disease pathogenesis in the remaining PDB patients is still unknown. Therefore association studies investigating the relationship between genetic polymorphisms and sporadic PDB have been performed in order to find the susceptibility polymorphisms.

Bone overgrowth-associated mutations in the LRP4 gene impair sclerostin facilitator function.

Humans lacking sclerostin display progressive bone overgrowth due to increased bone formation. Although it is well established that sclerostin is an osteocyte-secreted bone formation inhibitor, the underlying molecular mechanisms are not fully elucidated. We identified in tandem affinity purification proteomics screens LRP4 (low density lipoprotein-related protein 4) as a sclerostin interaction partner.

Identification and functional characterization of a missense mutation in resistin in two patients with severe obesity and insulin resistance.

Objective: In this study, we hypothesized that mutations in the resistin encoding gene, RETN, may cause a monogenic form of obesity.

Design/methods: We screened the coding region of RETN in 81 morbidly obese adults, 263 overweight and obese children/adolescents, and 116 healthy lean subjects. In vitro experiments include qPCR, ELISA, and western blot for WT and mutant resistin transfected into 3T3-L1 adipocytes.

Association study of MC4R with complex obesity and replication of the rs17782313 association signal.

Recently, genome-wide association studies have discovered several single nucleotide polymorphisms (SNPs) involved in the etiology of complex obesity. A variant downstream from the melanocortin-4 receptor gene (MC4R), a gene known to be involved in monogenic obesity, was reported to be highly associated with BMI. In the present study, we performed a replication study with the previously reported SNP rs17782313.

Identification and functional characterization of novel mutations in the melanocortin-4 receptor.

Objective: Melanocortin-4 receptor (MC4R) deficiency is the most common cause of monogenic obesity. In the present study, we screened the MC4R gene for mutations in a population of overweight and obese children and adolescents.

Method: Cross-sectional mutation analysis of 112 overweight/obese children and adolescents and 121 lean individuals.

First missense mutation in the SOST gene causing sclerosteosis by loss of sclerostin function.

Sclerosteosis is a rare bone dysplasia characterized by greatly increased bone mass, especially of the long bones and the skull. Patients are tall, show facial asymmetry and often have syndactyly. Clinical complications are due to entrapment of cranial nerves.

Genetic variation in the TNFRSF11A gene encoding RANK is associated with susceptibility to Paget's disease of bone.

RANK (receptor activator of nuclear factor-κB), encoded by TNFRSF11A, is a key protein in osteoclastogenesis. TNFRSF11A mutations cause Paget's disease of bone (PDB)-like diseases (ie, familial expansile osteolysis, expansile skeletal hyperphosphatasia, and early-onset PDB) and an osteoclast-poor form of osteopetrosis. However, no TNFRSF11A mutations have been found in classic PDB, neither in familial nor in isolated cases.

Identification of three novel genetic variants in the melanocortin-3 receptor of obese children.

The melanocortin-3 receptor (MC3R), a G-protein-coupled receptor expressed in the hypothalamus, is a key component of the leptin-melanocortin pathway that regulates energy homeostasis. It is suggested that an MC3R defect leads to an increased feed efficiency, by which nutrients are partitioned preferentially into fat. In this study, we hypothesized that early-onset obesity could be induced by mutations in MC3R.

Osteopathia striata with cranial sclerosis owing to WTX gene defect.

Osteopathia striata with cranial sclerosis (OSCS) is an X-linked dominant condition marked by linear striations mainly affecting the metaphyseal region of the long bones and pelvis in combination with cranial sclerosis. Recently, the disease-causing gene was identified as the WTX gene (FAM123B), an inhibitor of WNT signaling. A correlation was suggested between the position of the mutation and male lethality.

Association study and mutation analysis of adiponectin shows association of variants in APM1 with complex obesity in women.

We performed an association study and mutation analysis of the adiponectin (APM1) gene to study its involvement in the development of obesity. We also studied the interaction with peroxisome proliferator-activated receptor gamma (PPARgamma). 223 obese women and 87 healthy female control subjects were used for association analysis.

Analysis of genetic variations in the resistin gene shows no associations with obesity in women.

Resistin is thought to be involved in the development of obesity and insulin resistance. Polymorphisms in the gene encoding resistin could contribute to this link, but different studies have yielded contradictory results. In this study, we investigated whether polymorphisms in resistin are involved in the development of obesity in a Belgian female population.

A new heterozygous mutation (R714C) of the osteopetrosis gene, pleckstrin homolog domain containing family M (with run domain) member 1 (PLEKHM1), impairs vesicular acidification and increases TRACP secretion in osteoclasts.

Unlabelled: We studied phenotypic and cellular aspects in a patient with a heterozygous mutation of the PLEKHM1 gene and obtained some indications regarding the role of the protein in bone cell function. Plekhm1 is involved in osteoclast endosomal vesicle acidification and TRACP exocytosis, contributing to events involved in osteoclast-osteoblast cross-talk.

Introduction: The gene PLEKHM1 encodes a nonsecretory adaptor protein that localizes to endosomal vesicles.

Identification of sex-specific associations between polymorphisms of the osteoprotegerin gene, TNFRSF11B, and Paget's disease of bone.

Unlabelled: We studied the role of TNFRSF11B polymorphisms on the risk to develop Paget's disease of bone in a Belgian study population. We observed no association in men, but a highly significant association was found in women, and this was confirmed in a population from the United Kingdom.

Introduction: Juvenile Paget's disease has been shown to be caused by mutations in TNFRSF11B encoding osteoprotegerin.