Apolipoprotein E genotype may influence urinary gammacarboxyglutamate (Gla) concentrations in young individuals

Upon degradation of vitamin K-dependent proteins (known as Gla-proteins) the free aminoacid Gla cannot be re-utilized and is excreted in the urine, where it can be used as an overall marker for vitamin K status. We report the urinary Gla excretion values in first morning void urine for healthy young Romanian subjects from birth, childhood and young adulthood. In these subjects we have evaluated age, gender and apo E genotype as potential confounders. The urinary free Gla/creat ratio (Gla/creat, mg/g) was highest in newborns (34.8 ± 19.5; p < 0.001), than fell in the group 4 to 48 months old (13.1 ± 11.1) to levels that were not significantly different from the young adult group (18.3 ± 5.5). No gender-related differences were observed in Gla/creat in newborns and young children, but Gla excretion in women was higher than in men (28.6%; p < 0.029). Remarkably, Gla excretion in subjects bearing the apo ε2+ allele was significantly lower (11.9 ± 4.2) than in those bearing combinations of the ε3+ and ε4+ alleles (20.3 ± 4.1). The novelty of this study resides in the evaluation of urinary Gla excretion in relation with apo E genotype, suggesting that apo ε2 allele is a risk factor for developing vitamin K insufficiency.