ACEandACTN3Genotypes in Older Women: Muscular Phenotypes

Abstract

This study examined the association between ACE I/D and ACTN3 R577X polymorphisms and muscle-related phenotypes and their adaptation to resistance training in older women. Volunteers (n=246;age=66.7 ± 5.5 years) underwent quadriceps strength assessment using isokinetics and fat-free mass by dual energy X-ray absorptiometry. 79 volunteers performed 24 weeks of resistance training and 75 were studied as controls. Genotypes were identified by standard procedures. No associations were observed for muscle strength for either gene, but volunteers carrying the D/D genotype presented higher appendicular fat-free mass compared to the I-allele carriers (6.3 ± 0.1 vs. 6.1 ± 0.1 kg/m (2)). The X-allele carriers presented higher relative fat-free mass when compared to homozygous R/R (16.3 ± 0.1 vs. 15.9 ± 0.1 kg/m (2)). All fat-free mass variables were significantly greater for carriers of both X/X and D/D genotypes. In response to RT, only the I-allele carriers significantly increased fat-free mass and a significant training × genotype interaction was noted. These findings do not support a pivotal role for the studied polymorphisms in determining muscle strength in older women, but suggest a modest role in fat-free mass determination. Of note, the results provide a novel insight that these genetic variations may interact to determine muscle mass in older women.

Genes and the ageing muscle: a review on genetic association studies

“…McCauley et al found no association with indices of muscularity (whole body or thigh non-skeletal lean mass) in older Caucasian men (McCauley et al 2010). In contrast, in the aforementioned study by Lima et al women who were X allele carriers presented higher relative FFM at baseline compared with RR women (Lima et al 2011). Zempo et al (2010) showed that Japanese women with the XX genotype had lower thigh muscle CSA compared with RR and RX genotypes.…”

“…strength (using isokinetics) at baseline in Brazilian old women (Lima et al 2011). In contrast, others found an association between the ACTN3 R577X variation and muscle phenotypes in old people, yet with controversial results with regards to which allele (R or X) has a favourable or unfavourable effect.…”

“…In men, absolutes changes in peak power after training approached a significantly higher value in the XX group, whereas women with the RR genotype showed significantly greater training improvements in relative peak power than their XX counterparts. However, Lima et al (2011) reported no significant association between ACTN3 genotypes and RT adaptations. Finally, a recent report showed that carriage of the X allele (one or two copies) was significantly associated with increased risk of falling over time (Judson et al 2011).…”

“…However, no genotype association was found with the muscle volume adaptation in response to RT. Lima et al (2011) recently reported that, among old Brazilian women who performed quadriceps RT during 24 weeks, FFM was increased after training only in the I allele carriers.…”

“…Published findings are also controversial in older people, starting with the possible association between this polymorphism and muscle mass. Some studies reported a positive association between the D allele and the following phenotypes: muscle mass in healthy inactive old men and women (Charbonneau et al 2008), lean mass (as well as handgrip force) in advanced cancer patients (Vigano et al 2009) or appendicular fat free fat (FFM) in old women (Lima et al 2011). In contrast, McCauley et al found no association with whole body and thigh lean mass in old Caucasians (McCauley et al 2010).…”