Influence of infant fucosyltransferase polymorphisms on the association of maternal secretor status with child outcomes: the Ulm birth cohort studies

The influence of maternal secretor status and child fucosyltransferase (FUT2) polymorphisms on respiratory and ear infections, and growth, is an emerging research area. But, the impact of discordant secretor status between mother and infant, where their secretor status differs, remains underexplored. This study investigated how infant FUT2 single nucleotide polymorphisms (SNPs) modify the association between maternal secretor/non-secretor milk phenotypes and child outcomes such as infections, and growth during the first two years of life in discordant mother-infant pairs. Data from n = 539 mother-infant pairs in the Ulm SPATZ Health Study (SPATZ) and n = 488 pairs in the Ulm Birth Cohort Study (UBCS) were analysed using logistic, modified Poisson, and linear regression models. A significant proportion of infants in both cohorts were heterozygous secretors (46% in SPATZ and 45% in UBCS), and about a third had discordant secretor status with their mothers. Non-secretor infants receiving secretor milk in SPATZ showed a significant increase in BMI between week 4/5 and month 3/4 compared to secretor infants. But these associations were not significant after adjusting for confounders and correcting for multiple testing (α threshold = 0.0035). Despite the non-significant results, the findings emphasize the need for further research on discordant secretor status and its health implications.