Circulating amounts of osteoprotegerin and RANK ligand: Genetic influence and relationship with BMD assessed in female twins

Serum OPG and RANKL levels have only a weak relation to BMD in healthy women. Phenotype correlations indicate that the genes that contribute to twin similarity for BMD are not genes regulating serum levels of RANKL or OPG. The weak correlation with BMD appears to consist in shared environmental factors.