FAM210A is a novel determinant of bone and muscle structure and strength.

Osteoporosis and sarcopenia are common comorbid diseases, yet their shared mechanisms are largely unknown. We found that genetic variation near FAM210A was associated, through large genome-wide association studies, with fracture, bone mineral density (BMD), and appendicular and whole body lean mass, in humans. In mice, Fam210a was expressed in muscle mitochondria and cytoplasm, as well as in heart and brain, but not in bone. Grip strength and limb lean mass were reduced in tamoxifen-inducible Fam210a homozygous global knockout mice (TFam210a(-/-) ), and in tamoxifen-inducible Fam210 skeletal muscle cell-specific knockout mice (TFam210aMus(-/-) ). Decreased BMD, bone biomechanical strength, and bone formation, and elevated osteoclast activity with microarchitectural deterioration of trabecular and cortical bones, were observed in TFam210a(-/-) mice. BMD of male TFam210aMus(-/-) mice was also reduced, and osteoclast numbers and surface in TFam210aMus(-/-) mice increased. Microarray analysis of muscle cells from TFam210aMus(-/-) mice identified candidate musculoskeletal modulators. FAM210A, a novel gene, therefore has a crucial role in regulating bone structure and function, and may impact osteoporosis through a biological pathway involving muscle as well as through other mechanisms.