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Lack of concordance and linkage disequilibrium among brothers for androgenetic alopecia and CAG / GGC haplotypes of the androgen receptor gene in Mexican families
Author(s) -
ArteagaVázquez Jazmín,
LópezHernández María A.,
Svyryd Yevgeniya,
Mutchinick Osvaldo M.
Publication year - 2015
Publication title -
journal of cosmetic dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.626
H-Index - 44
eISSN - 1473-2165
pISSN - 1473-2130
DOI - 10.1111/jocd.12159
Subject(s) - haplotype , genetics , linkage disequilibrium , concordance , exon , sanger sequencing , genetic predisposition , medicine , biology , genotype , gene , mutation
Summary Background Androgenetic alopecia ( AGA ) or common baldness is the most prevalent form of hair loss in males. Familial predisposition has been recognized, and heritability estimated in monozygotic twins suggests an important genetic predisposition. Several studies indicate that the numbers of CAG / GGC repeats in exon 1 of the androgen receptor gene ( AR ) maybe associated with AGA susceptibility. Aims To investigate a possible correlation between AR CAG / GGC haplotypes and the presence or not of alopecia in sibships with two or more brothers among them at least one of them has AGA . Patients/Methods Thirty‐two trios including an alopecic man, one brother alopecic or not, and their mother were enrolled. Sanger sequencing of the exon 1 of the AR gene was conducted to ascertain the number of CAG / GGC repeats in each individual. Heterozygous mother for the CAG / GGC haplotypes was an inclusion criterion to analyze the segregation haplotype patterns in the family. Concordance for the number of repeats and AGA among brothers was evaluated using kappa coefficient and the probability of association in the presence of genetic linkage between CAG and GGC repeats and AGA estimated by means of the family‐based association test ( FBAT ). Results The median for the CAG and GGC repeats in the AR is similar to that reported in other populations. The CAG / GGC haplotypes were less polymorphic than that reported in other studies, especially due to the GGC number of repeats found. Kappa coefficient resulted in a concordance of 37.3% ( IC 95%, 5.0–69.0%) for the AGA phenotype and identical CAG / GGC haplotypes. There was no evidence of linkage disequilibrium. Conclusion Our results do not confirm a possible correlation or linkage disequilibrium between the CAG / GGC haplotypes of the AR gene and androgenetic alopecia in Mexican brothers.