title: [Genetic causes of obesity].
abstract: BACKGROUND
  Overweight and obesity represent an increasing health problem. Both genetic and environmental factors contribute to the development of obesity. This article summarises the genetic aspects of these conditions.
  
  
  METHODS
  A literature search was conducted using PubMed and OMIM. Both original and review articles were included.
  
  
  CONCLUSIONS
  The genetic influence on body weight is shown by twin and family studies. Environmental changes in recent decades have promoted the development of obesity in individuals at risk because of their genetic composition. Our understanding of the molecular pathways underlying common obesity is limited. During the last decade a handful of monogenic disorders leading to early, severe obesity in humans have been identified. All affect the central regulation of appetite. These conditions are rare, except for mutations in the melanocortin 4 receptor that account for about 5% of morbidly obese patients (BMI > 40 kg/m). The identification of monogenic forms of obesity has contributed valuable insight into the regulation of appetite and development of obesity, although causal treatment only exists for leptin deficiency. In addition, several well defined Mendelian syndromes are associated with overweight and obesity. The molecular genetic cause is known for some of these syndromes, but how appetite and energy balance are affected is still unclear.
authors.affiliation: Avdeling for medisinsk genetikk, Ullevål universitetssykehus, og Institutt for medisinsk genetikk, Universitetet i Oslo. teresia.wangensteen@medisin.uio.no
authors.forename: Teresia
authors.initials: T
authors.lastname: Wangensteen
authors.forename: Dag
authors.initials: D
authors.lastname: Undlien
authors.forename: Serena
authors.initials: S
authors.lastname: Tonstad
authors.forename: Lars
authors.initials: L
authors.lastname: Retterstøl
mesh_terms: D000328:Adult; D001066:Appetite / Q000235:genetics; D002648:Child; D020022:Genetic Predisposition to Disease; D006801:Humans; D009765:Obesity / Q000209:etiology / Q000235:genetics*; D009767:Obesity, Morbid / Q000235:genetics; D050177:Overweight / Q000235:genetics*; D044105:Receptor, Melanocortin, Type 4 / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D054411:Receptors, Leptin; D012307:Risk Factors; D013577:Syndrome
chemical_list: D044105:Receptor, Melanocortin, Type 4; D011956:Receptors, Cell Surface; D054411:Receptors, Leptin