Variants of the MSTN gene are associated with muscle hypertrophy phenotypes in a range of mam- malian species (Grobet et al. 1997; McPherron et al. 1997; McPherron and Lee 1997; Mosher et al. 2007). Myostatin expression increases might contribute to muscle wasting, as suggested by research in animal (immobilised mice) (Carlson et al. 1999) and human models, i.e. HIV infection (Gonzalez-Cadavid et al. 1998), critically ill patients (Constantin et al. 2011) or cachexia (Dasarathy et al. 2004). One study showed that serum myostatin levels increased with age, sug- gesting an association between myostatin and age- associated sarcopenia (Yarasheski et al. 2002). However, others have shown that myostatin expres- sion does not increase (Kawada et al. 2001; Welle et al. 2002), and can even decrease (Baumann et al. 2003), in ageing-induced sarcopenia in humans or rodents, thus questioning its involvement in muscle mass wasting during ageing. In fact, the R allele has not been associated with higher muscle mass/function in old Caucasian people (aged <80 years) (see Garatachea and Lucía (2013) for a review). Carriage of one R allele does not seem to exert a major influ- ence in the muscle phenotypes of non-agenarians (Gonzalez-Freire et al. 2010) whereas, surprisingly, the only two reported Caucasian old people with the RR genotype (i.e. a Spanish woman aged 96 years and an Italian person with assumed age <80 years) seemed to have lower muscle strength than their age-matched peers (Corsi et al. 2002; Gonzalez-Freire et al. 2010). Nonetheless, given the low frequency of the R allele, further research with larger population samples is

In summary, the variant R allele of the MSTN K153R polymorphism was significantly more frequent in centenarians than in the control group. Although more research is needed, this genetic variation could

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/j.biocel.

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Acknowledgments This study was funded by the Fondo de Investigaciones Sanitarias (FIS, ref. # PS09/00194).

References