Fine-Mapping of Xq25.1-27.2 Shows Association of Early Childhood Caries with Genetic Variants Depending on Dietary Habits, Protecting Children Who Drink Milk before Going to Bed.

Early childhood caries (ECC) is a chronic, infectious disease that affects the primary dentition of young children. It is the result of unequal contributions of risk factors and protective factors that influence the disease. The aim of this study was to assess if the X chromosome region previously linked to caries was associated with ECC. Two hundred and fifty-nine unrelated children with no chronic illnesses from 2 to 5 years of age who had no systemic fluoride consumption were evaluated using a cross-sectional design. Data on oral habits were obtained through a questionnaire, and caries experience data were collected by clinical examination. Twenty-three markers in ten genes were studied. Genotyping of the selected polymorphisms was carried out by real-time polymerase chain reaction. Regression analyses were performed comparing individuals with and without caries experience. Of 259 subjects, 123 were caries free. The markers in Xq25.1-27.2 were associated with ECC when children were using milk bottle for longer times (p = 0.01) and had more snacks over the course of a day (p = 0.05). Conversely, the markers in the X chromosome studied here were protective for ECC (p = 0.008) in children consuming milk before going to sleep. The genes located in the X chromosome possibly contribute to ECC and have an impact on ECC depending on the dietary habits.