ESPE Abstracts

Introduction and aims: MEST (Mesoderm-specific transcript), a candidate gene for Silver-Russell syndrome, is a paternally expressed imprinted gene that positively regulates foetal growth. MEST has also been shown to promote adipose tissue expansion in conditions of positive energy balance. In this context, our objective was to study the possible relationship between placental MEST gene expression and postnatal growth and obesity parameters in otherwise healthy newborns.

Subjects and Methods: The study population consisted of 109 pregnant women and their newborns who were followed from birth until six years of age. All mothers and newborns were healthy, all with term pregnancies and infants’ weights appropriate for gestational age. The study population was divided into two groups according to birth weight of the offspring [newborns with higher birth weight (n=58) and newborns with lower birth weight (n=51), according to the 50^th percentile of the studied population]. MEST gene expression was assessed by RT-PCR in placenta samples. Associations of placental MEST expression and various growth and obesity parameters in the offspring during the first year of life and at six years of age [weight, height, body mass index (BMI), fat and lean mass, among others] were assessed.

Results: Placental MEST expression did not show significant associations with the examined parameters in the offspring when the subjects were studied together as a whole. Nevertheless, associations were elicited when analysing separately the two groups of newborns with either higher or lower birth weight. In the group of higher birth weight (>50^th percentile), MEST expression in the placenta was positively associated with weight-SDS, BMI-SDS and fat mass at six years of age (all β ≥0.42, P≤0.006), while in the group with lower birth weight (<50^th percentile), MEST expression was negatively associated with weight-SDS at 12 months of age, and with weight-SDS, height-SDS, fat mass and lean mass at 6 years of age (all β ≤-0.31, P<0.05 to P<0.001). All these independent associations were derived from linear regression models adjusting for possible confounding variables (maternal smoking, maternal pre-gestational BMI, age and sex of the offspring).

Conclusion: MEST expression in the placenta associates with various parameters of growth and obesity in newborns followed from birth until 6 years of age. Our results suggest that MEST expression may have a prevalent role in postnatal growth and adiposity that is dependent on the previous growth of the infant, likely reflecting a condition of either positive or negative energy balance.