The exon-1 of the androgen receptor (AR) gene contains two repeat length polymorphisms which modify either the amount of AR protein inside the cell (GGNn, polyglycine) or its transcriptional activity (CAGn, polyglutamine). Shorter CAG and/or GGN repeats provide stronger androgen signalling and vice versa. To test the hypothesis that CAG and GGN repeat AR polymorphisms affect muscle mass and various variables of muscular strength phenotype traits, the length of CAG and GGN repeats was determined by PCR and fragment analysis and confirmed by DNA sequencing of selected samples in 282 men (28.6±7.6 years). Individuals were grouped as CAG short (CAGS) if harbouring repeat lengths of ≤21 and CAG long (CAGL) if CAG >21. GGN was considered short (GGNS) or long (GGNL) if GGN ≤23 or >23, respectively. No significant differences in lean body mass or fitness were observed between the CAGS and CAGL groups, or between GGNS and GGNL groups, but a trend for a correlation was found for the GGN repeat and lean mass of the extremities (r=−0.11, p=0.06). In summary, the lengths of CAG and GGN repeat of the AR gene do not appear to influence lean mass or fitness in young men.
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Competing interests None.
Funding The study was supported by Ministerio de Educación y Ciencia (DEP2006-56076-C06-04/ACTI) and FEDER, Consejería de Educación, Cultura y Deportes del Gobierno de Canarias (2006/179 0001 and FEDER), Proyecto Interreg IIIB BIOPOLIS, Fundación del Instituto Canario de Investigación del Cáncer (FICIC), Cabildo de Gran Canaria, Cabildo de Tenerife and La Caja de Canarias, and Proyecto Estructurante “Integración de los grupos de investigación en Ciencias de la Salud entorno al estudio de la obesidad y el síndrome metabólico con un enfoque molecular, celular, fisiopatológico, epidemiológico y psicosocial”, ULPGC, Gobierno de Canarias.
Ethics approval This study was conducted with the approval of the University of Las Palmas de Gran Canaria.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent Obtained.