👤 Steven A Berkowitz

This systematic review synthesized research evaluating the relationship between genetic predictors and weight loss after bariatric surgery. Fifty-seven studies were identified that examined single genes or genetic risk scores. Uncoupling protein (UCP) rs660339 was associated with excess weight loss after surgery in 4 of 6 studies. The most commonly assessed genes were fat mass and obesity-associated (FTO) gene (n = 10) and melanocortin-4 receptor (MC4R) (n = 14). Both were inconsistently related to weight loss. Genetic risk scores predicted weight loss in 6 of 7 studies. This evidence suggests the potential of using genetic variants and genetic risk scores to predict the amount of weight loss anticipated after bariatric surgery and identify patients who may be at risk for suboptimal weight reduction. Show less

Although hundreds of genome-wide association studies-implicated loci have been reported for adult obesity-related traits, less is known about the genetics specific for early-onset obesity and with only a few studies conducted in non-European populations to date. Searching for additional genetic variants associated with childhood obesity, we performed a trans-ancestral meta-analysis of 30 studies consisting of up to 13 005 cases (≥95th percentile of body mass index (BMI) achieved 2-18 years old) and 15 599 controls (consistently <50th percentile of BMI) of European, African, North/South American and East Asian ancestry. Suggestive loci were taken forward for replication in a sample of 1888 cases and 4689 controls from seven cohorts of European and North/South American ancestry. In addition to observing 18 previously implicated BMI or obesity loci, for both early and late onset, we uncovered one completely novel locus in this trans-ancestral analysis (nearest gene, METTL15). The variant was nominally associated with only the European subgroup analysis but had a consistent direction of effect in other ethnicities. We then utilized trans-ancestral Bayesian analysis to narrow down the location of the probable causal variant at each genome-wide significant signal. Of all the fine-mapped loci, we were able to narrow down the causative variant at four known loci to fewer than 10 single nucleotide polymorphisms (SNPs) (FAIM2, GNPDA2, MC4R and SEC16B loci). In conclusion, an ethnically diverse setting has enabled us to both identify an additional pediatric obesity locus and further fine-map existing loci. Show less

Obesity is a serious health concern for children and adolescents, particularly in Western societies, where its incidence is now considered to have reached epidemic proportions. A number of genetic determinants of adult BMI have already been established through genome wide association studies (GWAS), most recently from the GIANT meta-analysis of such datasets combined. In this current study of European Americans, we examined the 32 loci detected in that GIANT study in the context of common childhood obesity within a cohort of 1,097 cases (defined as BMI ≥95th percentile), together with 2,760 lean controls (defined as BMI <50th percentile), aged between 2 and 18 years old. Nine of these single-nucleotide polymorphims (SNPs) yielded at least nominal evidence for association with common childhood obesity, namely at the FTO, TMEM18, NRXN3, MC4R, SEC16B, GNPDA2, TNNI3K, QPCTL, and BDNF loci. However, overall 28 of the 32 loci showed directionally consistent effects to that of the adult BMI meta-analysis. We conclude that among the 32 loci that have been reported to associate with adult BMI in the largest meta-analysis of BMI to date, at least nine also contribute to the determination of common obesity in childhood in European Americans, as demonstrated by their associations in our pediatric cohort. Show less

Monoclonal antibodies (Mabs) are a favorite drug platform of the biopharmaceutical industry. Currently, over 20 Mabs have been approved and several hundred others are in clinical trials. The anti-LINGO-1 Mab Li33 was selected from a large panel of antibodies by Fab phage display technology based on its extraordinary biological activity in promoting oligodendrocyte differentiation and myelination in vitro and in animal models of remyelination. However, the Li33 Fab had poor solubility when converted into a full antibody in an immunoglobulin G1 framework. A detailed analysis of the biochemical and structural features of the antibody revealed several possible reasons for its propensity to aggregate. Here, we successfully applied three molecular approaches (isotype switching, targeted mutagenesis of complementarity determining region residues, and glycosylation site insertion mutagenesis) to address the solubility problem. Through these efforts we were able to improve the solubility of the Li33 Mab from 0.3 mg/mL to >50 mg/mL and reduce aggregation to an acceptable level. These strategies can be readily applied to other proteins with solubility issues. Show less