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Neurons expressing pro-opiomelanocortin (Pomc) regulate food intake and body weight. Here the authors show that Steroid Receptor Coactivator-1 (SRC-1) regulates the function of Pomc expressing neurons, and that rare heterozygous variants found in obese individuals lead to loss of SRC-1 function.

The authors explore the impact of MC4R deficiency on lipid metabolism in humans, based on two large cohorts. Findings indicate that individuals with obesity due to MC4R deficiency have lower cholesterol and triglyceride levels, as well as reduced cardiovascular risk.

Sadaf Farooqi, Inês Barroso and colleagues report genome-wide SNP and CNV association analyses for severe obesity in children, selected at the extreme of the distribution for body mass index. They identify four loci newly associated with severe obesity, an enrichment of rare CNVs in severely obese cases and overlap in the loci associated with severe obesity in children and with BMI and obesity in the general population.

Hypothalamic melanocortin-4-receptors (MC4R) regulate food preference in rodents, but their role in humans is unclear. Here, the authors perform food preference and liking tests in humans with MC4R mutations and find that they prefer fatty food more, but sweet food less, than people without MC4R mutations.

Analyzing data from the SURMOUNT-1 trial, the authors show that the weight loss effects of tirzepatide treatment are similar in carriers and noncarriers of MC4R pathogenic mutations.

The brain-expressed receptor GPR10 is involved in energy homeostasis in mice. Here the authors identify rare loss of function variants in GPR10 in people with severe obesity and showed that one of these variants causes obesity when modelled in mice, suggesting that future studies could explore GPR10 as a potential target for weight-loss therapy.

Epidemiological analyses coupled with immunological phenotyping suggest that humoral immunity induced by COVID-19 vaccines wanes more rapidly in individuals with severe obesity compared to individuals with a BMI within the normal range.

A multi-ancestry genome-wide association study for age at menarche followed by fine mapping and downstream analysis implicates 665 pubertal timing genes, such as the G-protein-coupled receptor 83 (GPR83) and other genes expressed in the ovaries involved in the DNA damage response.

The contribution of copy number variation to obesity — a highly heritable and genetically heterogeneous disorder — is investigated in 300 Caucasian patients to reveal that large, rare deletions are significantly enriched in patients compared to controls. Several rare copy number variants are identified that are recurrent in patients but absent or at much lower prevalence in controls.

Analyses of whole-exome sequencing data identify rare loss-of-function variants in BSN associated with adult-onset obesity, type 2 diabetes and fatty liver disease, with stronger effect sizes than those observed for variants in known obesity risk genes such as MC4R.

A growing field of research aims to examine the potential overlap between the characteristics and underlying mechanisms of drug addiction and obesity. Here, Fletcher and colleagues argue that there is not yet sufficient evidence to support a 'food addiction' model and call for caution in the application of this model to clinical and policy recommendations.

Ruth Loos and colleagues report results of a large genome-wide association study for body mass index. They identify 18 new loci associated with this trait, some of which map near key hypothalamic regulators of energy balance.

Identification and characterization of variants in HTR2C in people with severe obesity, reveals a role for serotonin 2C receptor in regulation of appetite, weight and behavior.

The hypothalamus controls systemic energy homeostasis. Here, the authors show that loss of microRNA-7 in hypothalamic neurons causes obesity, increased growth and endocrine dysfunction in mice, and report genetic evidence that links microRNA-7 to height and adiposity in humans.

The global obesity epidemic is clearly driven by environmental factors; however, inherited factors can also influence human adiposity. In this Review, the authors focus on the genes implicated in monogenic obesity syndromes. These genes encode components of the leptin–melanocortin pathway, which is critical for regulation of food intake and body weight.

Treatment with setmelanotide, a new-generation MC4R agonist, provides durable weight loss in hyperphagic, leptin receptor–deficient patients, suggesting a pharmacological avenue to treat patients with various MC4R pathway defects.

Exome-wide analysis identifies rare and low-frequency coding variants associated with body mass index. Gene-based meta-analysis and functional studies implicate 13 genes, eight of which are novel, and neuronal pathways as factors in human obesity.

Analysis of mutations in MC4R and associated anthropometric phenotypes in the ALSPAC birth cohort reveals a prevalence of heterozygous loss of function of 0.30% and provides evidence that these mutations are associated with substantial excess adiposity in early life.

Morris Brown and colleagues identify somatic mutations in ATP1A1 and CACNA1D in aldosterone-producing adenomas with features resembling zonaglomerulosa cells. They further show that the ATP1A1 mutations cause inward leak currents under physiological conditions, whereas the CACNA1D mutations induce a shift of voltage-dependent gating to more negative potentials and suppress channel inactivation.

Low read depth sequencing of whole genomes and high read depth exomes of nearly 10,000 extensively phenotyped individuals are combined to help characterize novel sequence variants, generate a highly accurate imputation reference panel and identify novel alleles associated with lipid-related traits; in addition to describing population structure and providing functional annotation of rare and low-frequency variants the authors use the data to estimate the benefits of sequencing for association studies.

Well over ten years ago, hints begin to emerge that the melanocortin system, implicated in adrenal function and skin pigmentation, might also regulate energy balance. In the 1990s, speculation gave way to hard data: a melanocortin receptor highly expressed in the brain was firmly established as a central regulator of food intake and fat mass.

Imputation uses genotype information from SNP arrays to infer the genotypes of missing markers. Here, the authors show that an imputation reference panel derived from whole-genome sequencing of 3,781 samples from the UK10K project improves the imputation accuracy and coverage of low frequency variants compared to existing methods.

Joel Hirschhorn and colleagues report results of a large-scale genome-wide association and replication study for obesity-related traits. The newly discovered loci are enriched for genes expressed in the central nervous system, and may thus contribute to weight gain by modulating food intake. Similar results are reported in a related study by Gudmar Thorleifsson and colleagues.

Size and shape of the brain are, among others, influenced by the dimensions of the skull. Here, the authors report genome-wide association studies for head circumference and intracranial volume in children and adults and the identification of nine common or low-frequency variants associated with these traits.

Severe congenital development defects such as Jeune syndrome can result from the malfunction of primary cilia and dynein. Here Schmidts et al. report unique biallelic null mutations in a gene encoding a dynein light chain, helping to explain the nature of ciliopathies in human patients.

Struan Grant and colleagues perform a meta-analysis of genome-wide association studies to identify loci influencing childhood obesity. They discover variants near OLFM4 and HOXB5 associated with this trait and show that these loci are also associated with increased body mass index in adults.