Low levels of vitamin D have been long linked to lack of sufficient dietary sources and sun exposure, but new research published online in the Lancet journal (Epub ahead of print, June 10, 2010) may add another clue: genetics. Researchers in the SUNLIGHT (Study of Underlynig Genetic Determinants of Vitamin D and Highly Related Traits) Consortium found 3 genetic variants may correlate to vitamin D deficiency in the body.
The researchers conducted a genome-wide association study of vitamin D biomarker 25-hydroxyvitamin D in 33,996 people of European descent and divided the subjects into three groups: 16,125 people used for discovery and the rest divided between two different methods of replication to strengthen results.
They also looked vitamin D concentrations in the blood, with deficiency defined as less than 75nmol/L or 50 nmol/L. To measure 25-hydroxyvitamin D they used radioimmunoassay, chemiluminescent assay, ELISA, or mass spectrometry.
In the discovery subject, who were U.S., Canadian and/or European citizens, variants near three genes (GC, DHCR7 and CYP2R1) reached significance for association with hydroxyvitamin D concentrations. The results were confirmed in the replication groups.
“Vitamin D is crucial for maintenance of musculoskeletal health, and might also have a role in extraskeletal tissues. Determinants of circulating 25-hydroxyvitamin D concentrations include sun exposure and diet, but high heritability suggests that genetic factors could also play a part,” the researchers wrote, noting variants near genes involved in cholesterol synthesis, hydroxylation, and vitamin D transport affect vitamin D status. “Whether genetic predisposition modifies response to sun exposure or dietary supplementation warrants further study.”