Blood cell transcript levels in 5-year-old children as potential markers of breastfeeding effects in those small for gestational age at birth.

Altogether, these results suggest that small for gestation age infants are more sensitive to the type of feeding during lactation, and transcript levels of particular genes in peripheral blood cells, especially the MC4R/UCP2 mRNA ratio, may precisely reflect these effects in the absence of clear differences in phenotypic traits.