Vitamin D is a precursor to the calcitriol hormone. Vitamin D can be obtained from the diet or synthesized in the skin from a cholesterol derivative. Skin synthesis of vitamin D requires exposure to ultraviolet sunlight. The active hormone of vitamin D has several functions in the body including maintaining calcium levels and bone health, stimulating immune system action and muscle function. A review in the "Mayo Clinic Proceedings" journal reports that nearly 36 percent of healthy young adults have an inadequate intake of vitamin D and the incidence of vitamin D deficiency is greater in certain populations like the elderly in long-term care facilities and people with certain diseases.
Genetics
More than half of the variation in serum vitamin D levels is influenced by genes and the other half by diet and sun exposure, a study in "PLoS One" notes. The specific genes haven't been well identified but are likely involved in vitamin D skin synthesis and vitamin D absorption, transport and storage. A study in the July 2010 issue of the "Lancet" reports that alterations in specific locations on chromosome 4 and 11 are linked to vitamin D deficiency. This study notes that the alterations are near genes that play a role in cholesterol synthesis, vitamin D metabolism and transport.
Hereditary Rickets
A rare genetic disorder of vitamin D deficiency is caused by a mutation in the gene that encodes for the vitamin D receptor. This protein is required for calcitriol to function in cells. Another rare mutation in the gene that encodes for a liver enzyme that is required for activation of vitamin D to calcitriol also causes vitamin D deficiency with rickets. Children with hereditary vitamin D resistance display severe bone abnormalities known as rickets.
Associated Diseases
Vitamin D deficiency is more prevalent in people with certain diseases like osteoporosis, chronic obstructive pulmonary disease, type-1 and type-2 diabetes, and breast, colon or prostate cancer. Alterations in genes that encode for the vitamin D receptor and vitamin D binding protein, which transports it to target tissues have been associated with osteoporosis, a study in "Calcified Tissue International" notes. A study in the journal "Thorax" reports that people with stage 3 and 4 chronic obstructive pulmonary disease that also had a gene alteration in the vitamin D binding protein were 76 and 100 percent, respectively to have excessively low levels of vitamin D.
References
- Mayo Clinic Proceedings: High Prevalence of Vitamin D Inadequacy and Implications for Health
- PubMed Central: PLoS One: Seasonal Genetic Influence on Serum 25-Hydroxyvitamin D Levels: A Twin Study
- The Lancet: Common Genetic Determinants of Vitamin D Insufficiency: A Genome-Wide Association Study
- PubMed Central: Calcified Tissue International: Vitamin D Binding Protein Genotype and Osteoporosis
Member Comments