Birth weight and parental PGM1 alleles

A deviation of the maternal-neonatal joint phosphoglucomutase locus 1 (PGM1) distribution from Hardy-Weinberg expectation has been reported. It was suggested that selection on PGM1 during intrauterine life might account for these deviations and that maternal and paternal PGM1 alleles might have different associations with intrauterine survival. This study considered possible associations between the joint mother-newborn PGM1 genotype and intrauterine growth. There was a significant association between birth weight percentile class and mother-newborn PGM1 genotype in infant females. Also, the paternal PGM1*2 allele was associated negatively with macrosomia, and this effect was significant only in female infants.

Human placental nitric oxide synthase activity is not altered in diabetes

Endothelial nitric oxide synthase (NOS) protein and mRNA have been identified and calcium-dependent NOS activity has been measured in human placentae during normal pregnancy. Recently, mRNA and protein for the inducible isoform of NOS have been detected in placentae of women with gestational diabetes. The aim of this study was to determine whether calcium-independent (ciNOS) and/or total (tNOS) NOS activities were increased in placentae obtained after vaginal delivery or Caesarean section from women assigned to the following groups according to standard obstetric criteria: gestational diabetes, diabetes before pregnancy and non-diabetic controls. tNOS and ciNOS were assessed by measuring the conversion of [3H]L-arginine to [3H]L-citrulline in the three groups. Michaelis-Menten constants (Km) and maximum velocities of reaction (Vmax) were calculated using Lineweaver-Burk analysis for tNOS. There were no significant differences in either ciNOS, Vmax or Km values between any of the three groups (normal, ciNOS 12.7+/-1.6%, Vmax 16.6+/-3.3 pmol.min-1.mg-1 protein, Km 15.30+/-2.6 micromol/l; gestational diabetes, ciNOS 15.4+/-1.4%, Vmax 14.8+/-5.2 pmol.min-1. mg-1 protein, Km 10.5+/-1.7 micromol/l; diabetes before pregnancy, ciNOS 13.4+/-1.1%, Vmax 14.9+/-3.4 pmol.min-1.mg-1 protein, Km 17. 7+/-2.2 micromol/l). The presence of macrosomia did not affect tNOS activity in those with diabetes before pregnancy, and glycosylated haemoglobin levels measured between weeks 27 and 39 were not correlated with ciNOS activity. The results from the present study do not provide evidence for increased placental tNOS or ciNOS activities in pregnancies complicated by gestational diabetes or diabetes present before pregnancy.

Foetal macrosomia and erythrocyte acid phosphatase (ACP1) polymorphism in diabetic and normal pregnancy

Both in diabetic and in normal pregnancy the proportion of macrosomic fetuses is much lower among newborns carrying Pc allele of erythrocyte acid phosphatase (ACP1) than among other ACP1 genotypes. In diabetic pregnancy the well known increased incidence of fetal macrosomia has been observed only among fetuses which do not carry this allele. ACP1 probably functions as a flavin-mononucleotide phosphatase. Since Pc allele is associated with the highest enzymatic activity it is likely that subjects carrying this gene may have a relatively lower concentration of flavin-mononucleotide cofactors and in turn a reduced rate of metabolic activities controlled by flavoenzymes. It is possible that in fetuses carrying Pc, flavo-enzyme activities are regulated at a level that does not allow a full response to stimuli (both genetic and/or environmental) aimed to maximize fetal growth.