Results
While DNA methylation of the
COX7A1 promoter was increased in muscle from elderly compared with young twins (19.9 ± 8.3% vs 1.8 ± 2.7%;
p = 0.035), the opposite was found for
COX7A1 mRNA expression (elderly 1.00 ± 0.05 vs young 1.68 ± 0.06;
p = 0.0005). The heritability of
COX7A1 expression was estimated to be 50% in young and 72% in elderly twins. One of the polymorphisms investigated, rs753420, influenced
basal
COX7A1 expression in muscle of young (
p = 0.0001) but not of elderly twins. The transcript level of
COX7A1 was associated with increased in vivo glucose uptake and
\mathop V· \textO\text2max \mathop V\limits^ \cdot {\text{O}}_{{\text{2max}}} (
p = 0.009 and
p = 0.001, respectively). We did not observe any genetic association between
COX7A1 polymorphisms and type 2 diabetes after correcting for multiple testing.