Objective: Melanocortin 1 receptor (MC1R) is involved in various functions, such as pigmentation, antipyretic and anti-inflammatory actions, development of melanoma, susceptibility to ultraviolet-induced sun damage, modification of oculocutaneous albinism, development of freckles, and mediation of female-specific mechanisms of analgesia. MC1R's natural agonists include α-melanocyte-stimulating hormone and corticotrophin (ACTH1-39), which are important components of hypothalamic pituitary adrenal axis and increase in response to stress. Given the multiple relevant roles of MC1R, we studied whether the MC1R gene would be associated with susceptibility to major depressive disorder or with response to antidepressant treatment.
Methods: The human MC1R gene is highly polymorphic; therefore, we sequenced the entire MC1R coding region of 1122 bp in 181 depressed Mexican–American patients and 185 Mexican-American controls.
Results: A total of 23 single nucleotide polymorphisms (SNPs, 15 known and eight new) were found within the sequenced region. Among the common SNPs, the nonsynonymous SNP, rs885479 (R163Q) was associated with the diagnosis of depression (P=0.04). The nonsynonymous SNP, rs2228479 (V92M) and the synonymous SNP, rs2228478 were found to be associated with the remission with desipramine treatment. No associations were found for remission with fluoxetine treatment or for the combined sample treated with fluoxetine or desipramine. The frequency of one (H2) of the five haplotypes identified was higher in depressed patients when compared with controls (P=0.05). In-silico functional analysis indicates that SNPs rs885479 and rs2228479 have significant impact on the protein function.
Conclusion: The MC1R gene might be associated with major depressive disorder and with treatment response to desipramine.
aCenter for Drug Screening and Research, State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, The Chinese Academy of Sciences, Yunnan, China
bDepartments of Neurology, and Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, Florida, USA
cJohn Curtin School of Medical Research, Australian National University, Australian Capital Territory, Australia
Correspondence to Dr Ma-Li Wong, MD, John Curtin School of Medical Research, Australian National University, Building 131, Garran Road, Canberra, ACT 2601, Australia Tel: +61 2 6125 8557; fax: +61 2 6125 2337; e-mail: email@example.com
Received January 31, 2010
Accepted May 8, 2010