title: Identification and functional characterization of a missense mutation in resistin in two patients with severe obesity and insulin resistance.
abstract: OBJECTIVE
  In this study, we hypothesized that mutations in the resistin encoding gene, RETN, may cause a monogenic form of obesity.
  
  
  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.
  
  
  RESULTS
  Mutation analysis identified five sequence variants in our patient populations: 3'-UTR +87 G/A, 3'-UTR +100 A/G, T73T, IV3-61 C/A, and C78S. In our control population, we only found the 3'-UTR +87 G/A variant. We started functional experiments for the C78S mutation that was found in a 20-year-old obese male (body mass index (BMI)=39.7 kg/m(2)) and his obese mother (BMI=31.9 kg/m(2)). In vitro testing demonstrated that the mutation does not impair mRNA expression. We identified a 100-fold lower extracellular protein concentration for mutant resistin compared with WT levels using a resistin ELISA on cell culture medium (P=4.87×10(-6)). We also detected a decreased intracellular concentration for the mutant protein (tenfold lower relative levels, P=0.007). The plasma resistin levels of the proband and his mother, however, did not differ significantly from lean control individuals.
  
  
  CONCLUSIONS
  In conclusion, we identified the first missense mutation in resistin in a morbidly obese proband and his obese mother. Functional testing of the mutant protein suggests that the C78S mutant protein is degraded, possibly resulting in a decreased extracellular concentration, which may predispose to obesity.
authors: Department of Medical Genetics, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
authors: Sigri
authors: S
authors: Beckers
authors: Fenna
authors: F
authors: de Freitas
authors: Doreen
authors: D
authors: Zegers
authors: An
authors: A
authors: Verrijken
authors: Armand V
authors: AV
authors: Peeters
authors: Frida
authors: F
authors: Peiffer
authors: Stijn L
authors: SL
authors: Verhulst
authors: Guy
authors: G
authors: Massa
authors: Ilse L
authors: IL
authors: Mertens
authors: Kristine N
authors: KN
authors: Desager
authors: Luc F
authors: LF
authors: Van Gaal
authors: Wim
authors: W
authors: Van Hul
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D041721:3T3-L1 Cells; D000293:Adolescent; D000328:Adult; D000818:Animals; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D002648:Child; D004252:DNA Mutational Analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005091:Exons / Q000235:genetics; D005190:Family; D005260:Female; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins; D006579:Heterozygote; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics*; D008297:Male; D051379:Mice; D008875:Middle Aged; D020125:Mutation, Missense / Q000235:genetics*; D009767:Obesity, Morbid / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D052243:Resistin / Q000235:genetics*; D014162:Transfection; D055815:Young Adult
chemical_list: D020413:3' Untranslated Regions; D012333:RNA, Messenger; D052243:Resistin; D049452:Green Fluorescent Proteins