With age, some people develop a condition called "sarcopenia" where they lose critical amounts of muscle mass, to the point that they develop functional impairments and disabilities. With the study, scientists hoped to pinpoint the genes associated with lean mass that may one day lead to therapies that will curtail loss of lean mass and prevent the onset of such disabilities.

The study published in the journal Nature Communications confirmed that lean mass is highly heritable. By understanding the genetic contributions to lean mass - an indicator of muscle mass - future treatments may be developed to prevent the loss of lean mass with aging.

This project involved more than 50 individual studies and a total of about 100,000 study participants from around the world that all contributed data to discover the genetic determinants of lean mass. The scientists also used information from many large pre-existing sources of genetic data to understand their findings, including information from individuals who had undergone muscle biopsies.

Authors found five single-nucleotide polymorphisms in/near HSD17B11, VCAN, ADAMTSL3, IRS1, and FTO for total lean body mass and for three single-nucleotide polymorphisms in/near VCAN, ADAMTSL3, and IRS1 for appendicular lean body mass. 

Ultimately the goal is to understand the biologic processes that lead to a loss of muscle mass, reduced physical strength, and frailty as people get older.

https://www.nature.com/articles/s41467-017-00031-7