Plasma and urinary amino acid concentrations in Down's syndrome: Effect of age

Background. - A preliminary study of plasma and urinary amino acid concentration in Down's syndrome subjects had shown some impairments. Patients and methods. - A comparative study of the variations of amino acid concentration with age in Down's syndrome subjects aged 0 to 60 years and in control subjects aged 0 to 94 years was made in order to determine whether these impairments could be explained by generalized premature aging, or by a specific gene dosage effect. Results. - Two major changes (P < 0.001) were found in Down's syndrome: a decrease in plasma concentration of serine at any age, which could be due to a dosage effect of cytathionine-beta-synthase, and an increase in plasma lysine concentration in patients above IO year's old probably due to premature aging. Other mirror changes were also present in plasma and urine, also possibly explained by premature aging. Conclusions. - Other studies are necessary to evaluate possible consequences of such changes in the amino acid profiles.