Correction to: Interplay between low plasma RANKL and VDR-FokI polymorphism in lumbar disc herniation independently from age, body mass, and environmental factors: a case–control study in the Italian population

Under the headline “Correlation of RANKL concentrations and VDR-FokI polymorphism on disc herniation” in the description text for Table 2, the term “allelic frequency” was used erroneously for “genotypic frequency”