Mutation analysis of the MCHR1 gene in human obesity.
OBJECTIVE
The importance of the melanin-concentrating hormone (MCH) system for regulation of energy homeostasis and body weight has been demonstrated in rodents. We analysed the human MCH receptor 1 gene (MCHR1) with respect to human obesity.


METHODS
This consisted of genomic screening of 13.4 kb encompassing the MCHR1 in extremely obese German children and adolescents and association analyses for two coding single nucleotide polymorphisms (SNPs). To confirm initial positive association results, additional association studies and transmission disequilibrium tests in further German, Danish, French and American samples were conducted. Selected SNPs were investigated using functional in vitro studies and reporter gene assays.


METHODS
Single-stranded conformation polymorphism analysis, re-sequencing, PCR-restriction fragment length polymorphism analyses, tetra-primer amplification refractory mutation systems, matrix-assisted laser desorption/ionization time of flight mass spectrometry and reporter gene assays were carried out as well as measuring inositol phosphate formation, inhibition of cAMP formation and activation of p42/44 MAP kinase.


RESULTS
We identified 11 infrequent variations and two SNPs in the MCHR1 coding sequence and 18 SNPs (eight novel) in the flanking sequence. Association and transmission disequilibrium with obesity were detected for several SNPs in independent study groups of German obese children and adolescents and controls. In two German samples, encompassing 4056 and 295 individuals, trends towards association with obesity were detected. Findings in a second epidemiological German sample and in Danish, French and American samples were negative. Functional in vitro studies as well as reporter gene assays revealed no significant results.


CONCLUSIONS
Our initial association of MCHR1 alleles/haplotype detected might be related to juvenile-onset obesity, conditional on a particular genetic and/or environmental background. Alternatively, we could not exclude the possibility that the initially detected association represented a false positive finding.
Wermter
Anne-Kathrin
AK
Clinical Research Group, Department of Child and Adolescent Psychiatry, Rheinische Kliniken Essen, University of Duisburg-Essen, 45147 Essen, Germany.
Reichwald
Kathrin
K
Büch
Thomas
T
Geller
Frank
F
Platzer
Cornelia
C
Huse
Klaus
K
Hess
Claudia
C
Remschmidt
Helmut
H
Gudermann
Thomas
T
Preibisch
Gerald
G
Siegfried
Wolfgang
W
Goldschmidt
Hans-Peter
HP
Li
Wei-Dong
WD
Price
R Arlen
RA
Biebermann
Heike
H
Krude
Heiko
H
Vollmert
Caren
C
Wichmann
H-Erich
HE
Illig
Thomas
T
Sørensen
Thorkild I A
TI
Astrup
Arne
A
Larsen
Lesli Hingstrup
LH
Pedersen
Oluf
O
Eberlé
Delphine
D
Clément
Karine
K
Blundell
John
J
Wabitsch
Martin
M
Schäfer
Helmut
H
Platzer
Matthias
M
Hinney
Anke
A
Hebebrand
Johannes
J
D000293:Adolescent; D000328:Adult; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000037:antagonists & inhibitors; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009765:Obesity / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D020641:Polymorphism, Single Nucleotide; D018807:Polymorphism, Single-Stranded Conformational; D011979:Receptors, Pituitary Hormone / Q000235:genetics*; D017422:Sequence Analysis, DNA
D007295:Inositol Phosphates; D011979:Receptors, Pituitary Hormone; C092274:melanin-concentrating hormone receptor; D004247:DNA; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases