Association of genetic variation with disproportionate vitamin A deficiency in pregnant women of certain ethnicities in the United States.

Vitamin A is an essential micronutrient that plays critical roles in many biological functions of the body. Limited access to vitamin A-rich food or supplements severely affects tissue and blood levels of vitamin A. Therefore, low serum vitamin A and poverty levels are strongly associated in vitamin A deficiency (VAD) studies that have focused mainly on developing countries. The current national prevalence rate of vitamin A deficiency in the United States is reported to be very low (<1%). However, several studies, including ours, have suggested that people from certain ethnic groups still face a higher proportion of vitamin A deficiency. We hypothesize that the genetic variations between ethnic groups may associate to the VAD proportional differences between women of different ancestries. To assess the associations, we re-analyzed two independent datasets of serum retinol levels of pregnant women in the United States and three datasets of genotypic information of different ancestries. We found that pregnant women with non-Hispanic Black and with Latin American/Afro-Caribbean ancestry have strikingly high proportions of VAD compared to non-Hispanic White and Latin American/Mexican ancestry. Genotypic analyses showed that the minor allele frequencis of genetic variants that associate to serum retinol levels have significantly higher variations between these different ancestries. Our study revealed that VAD rates in the pregnant women differ between different ancestries and that ancestry-dependent genetic variations might contribute to the differences.