👤 C F Dalton

Genetic factors are thought to play an important role in antipsychotic-induced weight gain (AIWG). Polygenic risk scores (PRS) could provide a measure of genetic predisposition to antipsychotic drug induced weight gain (AIWG).We conducted a study to examine how a PRS, generated using SNPs, identified from a recent meta-analysis, related to weight-change over time in people with first episode-psychosis. The PRS included SNPs in six different genes, identified as having significant associations (p < 0.05) with AIWG. These were HTR2C rs3813929; MTHFR rs1801133; ADRA2A rs1800544; MC4R rs489693; LEPR rs1137101 and CNR1 rs1049353. An additive PRS and a risk allele based weighted PRS were created based on risk allele counts and presence or absence of risk alleles respectively. The additive PRS was also used to create low/high genetic risk groups for analysis. The association between PRS and weight gain per day (WGPD) in grams/day as well as BMI percentage change (=> 7%) was investigated using regression models. In multiple regression analysis, the additive PRS significantly predicted AIWG in females (adjusted r We report a PRS that is predictive of weight gain in women treated for first episode psychosis, accounting for 59% of the variance daily weight-gain over time. Validation in an independent cohort is required, as is determining whether it is feasible to apply the PRS prospectively. Show less

Metabolic side effects represent a major long-term concern in antipsychotic (AP)-treated early psychosis. We evaluated the weight gain and changes in related metabolic parameters in patients followed up for 12 months. We also explored DNA methylation of four genes associated with weight gain (ADRA2A, INSIG2, LEP, MC4R). We included patients aged 15-64 years followed in the Ribeirão Preto Early Intervention in Psychosis Program from two different cohorts (Clinical sample, n = 147; Epigenetic sample, n = 59). DNA methylation was analysed by pyrosequencing only at baseline, after several weeks of AP exposure. In both cohorts, 40% of patients initially received second-generation antipsychotics (SGAs), increasing to over 70% after one year. Clinical sample: At follow-up, patients exhibited significant increases in body mass index (p < 0.001), triglycerides (p < 0.001), HDL-c (p = 0.001) and LDL-c (p < 0.001). Patients predominantly on SGAs during the 12 months had almost three times higher chance of weight gain than those using haloperidol. Other factors associated with weight gain included non-white skin colour (OR = 2.6), fewer years of schooling (OR = 2.5) and a weight gain of at least 7% at three months (OR = 3.1). Epigenetic sample: Patients receiving SGA treatment (median = 23.4 weeks) at baseline showed hypermethylation within the MC4R promoter region in relation to patients using haloperidol (median = 18.6 weeks). No changes in the baseline methylation of other genes related to weight gain or AP drugs were observed longitudinally. MC4R promoter hypermethylation in SGA-treated patients suggests drug-induced metabolic alterations and a potential role of MC4R as a biomarker for predicting AP-related metabolic risk. Show less

Genetic factors are thought to play an important role in antipsychotic-induced weight gain (AIWG). This study conducted a meta-analysis of current research of the pharmacogenetic associations of adult AIWG. The analysis included papers providing comparisons of weight gain across at least two allele combinations for at least one single nucleotide polymorphism (SNP). Inclusion criteria were, patients 18 years of age or older and had received a diagnosis of severe mental illness, for which antipsychotic medication was prescribed. The association with AIWG needed to be replicated across at least two papers reporting separate sample sets. Two hundred twenty-three papers were assessed for eligibility. Of the 223 papers, 148 were excluded, leaving 75 studies to be included. Six SNPs in six different genes were identified as having significant associations ( The study identified six SNPs that predispose adult individuals to AIWG, with Show less

The Koolen-de Vries syndrome (KdVS; OMIM #610443), also known as the 17q21.31 microdeletion syndrome, is a clinically heterogeneous disorder characterised by (neonatal) hypotonia, developmental delay, moderate intellectual disability, and characteristic facial dysmorphism. Expressive language development is particularly impaired compared with receptive language or motor skills. Other frequently reported features include social and friendly behaviour, epilepsy, musculoskeletal anomalies, congenital heart defects, urogenital malformations, and ectodermal anomalies. The syndrome is caused by a truncating variant in the KAT8 regulatory NSL complex unit 1 (KANSL1) gene or by a 17q21.31 microdeletion encompassing KANSL1. Herein we describe a novel cohort of 45 individuals with KdVS of whom 33 have a 17q21.31 microdeletion and 12 a single-nucleotide variant (SNV) in KANSL1 (19 males, 26 females; age range 7 months to 50 years). We provide guidance about the potential pitfalls in the laboratory testing and emphasise the challenges of KANSL1 variant calling and DNA copy number analysis in the complex 17q21.31 region. Moreover, we present detailed phenotypic information, including neuropsychological features, that contribute to the broad phenotypic spectrum of the syndrome. Comparison of the phenotype of both the microdeletion and SNV patients does not show differences of clinical importance, stressing that haploinsufficiency of KANSL1 is sufficient to cause the full KdVS phenotype. Show less

Pediatric osteosarcoma is characterized by multiple somatic chromosomal lesions, including structural variations (SVs) and copy number alterations (CNAs). To define the landscape of somatic mutations in pediatric osteosarcoma, we performed whole-genome sequencing of DNA from 20 osteosarcoma tumor samples and matched normal tissue in a discovery cohort, as well as 14 samples in a validation cohort. Single-nucleotide variations (SNVs) exhibited a pattern of localized hypermutation called kataegis in 50% of the tumors. We identified p53 pathway lesions in all tumors in the discovery cohort, nine of which were translocations in the first intron of the TP53 gene. Beyond TP53, the RB1, ATRX, and DLG2 genes showed recurrent somatic alterations in 29%-53% of the tumors. These data highlight the power of whole-genome sequencing for identifying recurrent somatic alterations in cancer genomes that may be missed using other methods. Show less

Olfactory receptor (OR) expression requires the transcriptional activation of 1 out of 1,000s of OR alleles and a feedback signal that preserves this transcriptional choice. The mechanism by which olfactory sensory neurons (OSNs) detect ORs to signal to the nucleus remains elusive. Here, we show that OR proteins generate this feedback by activating the unfolded protein response (UPR). OR expression induces Perk-mediated phosphorylation of the translation initiation factor eif2α causing selective translation of activating transcription factor 5 (ATF5). ATF5 induces the transcription of adenylyl cyclase 3 (Adcy3), which relieves the UPR. Our data provide a role for the UPR in defining neuronal identity and cell fate commitment and support a two-step model for the feedback signal: (1) OR protein, as a stress stimulus, alters the translational landscape of the OSN and induces Adcy3 expression; (2), Adcy3 relieves that stress, restores global translation, and makes OR choice permanent. Show less

Heparan sulfate (HS) has been implicated in regulating cell fate decisions during differentiation of embryonic stem cells (ESCs) into advanced cell types. However, the necessity and the underlying molecular mechanisms of HS in early cell lineage differentiation are still largely unknown. In this study, we examined the potential of EXT1(-/-) mouse ESCs (mESCs), that are deficient in HS, to differentiate into primary germ layer cells. We observed that EXT1(-/-) mESCs lost their differentiation competence and failed to differentiate into Pax6(+)-neural precursor cells and mesodermal cells. More detailed analyses highlighted the importance of HS for the induction of Brachyury(+) pan-mesoderm as well as normal gene expression associated with the dorso-ventral patterning of mesoderm. Examination of developmental cell signaling revealed that EXT1 ablation diminished FGF and BMP but not Wnt signaling. Furthermore, restoration of FGF and BMP signaling each partially rescued mesoderm differentiation defects. We further show that BMP4 is more prone to degradation in EXT1(-/-) mESCs culture medium compared with that of wild type cells. Therefore, our data reveal that HS stabilizes BMP ligand and thereby maintains the BMP signaling output required for normal mesoderm differentiation. In summary, our study demonstrates that HS is required for ESC pluripotency, in particular lineage specification into mesoderm through facilitation of FGF and BMP signaling. Show less

Many ion channels and transporters are regulated by ubiquitination mediated by the Nedd4 family of HECT-type ubiquitin ligases (E3s). These E3s commonly interact with substrates via their WW domains that bind to specific motifs in target proteins. However, not all potential targets of these E3s contain WW-binding motifs. Therefore, accessory proteins may mediate the interaction between Nedd4 family members and their targets. Here we report that the divalent metal ion transporter DMT1, the primary nonheme iron transporter in mammals, is regulated by ubiquitination mediated by the Nedd4 family member WWP2. DMT1 interacts with 2 WW domain-interacting proteins, Ndfip1 and Ndfip2, previously proposed to have roles in protein trafficking. This promotes DMT1 ubiquitination and degradation by WWP2. Consistent with these observations, Ndfip1(-/-) mice show increased DMT1 activity and a concomitant increase in hepatic iron deposition, indicating an essential function of Ndfip1 in iron homeostasis. This novel mechanism of regulating iron homeostasis suggests that Ndfips and WWP2 may contribute to diseases involving aberrant iron transport. Show less