Vitamin D is vital for forming strong, healthy bones. Researchers have identified genetics variations associated with of low vitamin D levels in children, opening up the possibility of identifying and treating individuals who are predisposed to have low vitamin D.
Adequate levels of vitamin D are vital for healthy growth and development, as it helps the body absorb calcium, a key mineral in bones. Low levels of vitamin D lead to rickets, in which the bones become deformed as a result of low mineralization during growth, or osteomalacia, in which the bones become soft in adulthood due to the loss of mineralization. Vitamin D is typically generated by the skin in response to sunlight or consumed in the diet. However, many populations live at very high latitudes where high seasonal sun exposure leads to variable levels of vitamin D throughout the year. Some of this variation in vitamin D levels appears to be inherited, which could have important implications for supplementation. As a result, there is a great deal of interest in determining the genetics of low vitamin D.
In the British Journal of Nutrition, Petersen and colleagues investigated genetic mutations linked to vitamin D variation in a group of 642 Danish children. The researchers asked children and their parents to record daily food intake, including vitamin D supplements, for seven days prior to assessing blood vitamin D levels. In addition, the researchers recorded the height, weight, and activity levels of each child. These assessments were made at three points representing three different seasons—autumn, winter, and spring. Petersen and colleagues also analyzed the genetic sequence of several genes related to vitamin D, to look for variants associated with vitamin D levels.
They found five minor variants of the genes CYP2R1 and GC that are strongly linked to low blood vitamin D levels. The CYP2R1 and GC genes both encode portions of the pathway that leads to the creation of vitamin D in the skin after exposure to sunlight. In genetics, a minor variant is a genetic variation that is present at low frequencies in a population. Children with these minor variants of CYP2R1 and GC had lower blood vitamin D levels throughout the year than children with more common variants, and these levels were on average below the recommended minimums. In particular, children with variants of GC did not experience an increase in blood vitamin D levels after winter.
These findings could have important consequences for improving vitamin D levels in children with minor genetic variants, who might be more prone to vitamin D insufficiency. However, the study only covered a 10-month period, which means that the researchers could not measure blood vitamin D levels during summer. Ethnicity and pubertal status were both dichotomized, meaning children were placed into one of two categories. This likely eliminates potential confounding factors in the sample. Further, the researchers made no direct measurements of children’s sun exposure during the study period.
Written By: C. I. Villamil