Alpha-1-antitrypsin and Down's syndrome

ABSTRACT

Serum levels of alpha-1-antitrypsin were determined in 37 infants and children and their parents. They were 20 cases of Down's syndrome, 7 cases of mosaic trisomy 21, 10 normal children and their consecutive parents. A significant decrease in mean serum alpha-1-anti-trypsin levels was found in mosaic Down syndrome cases in comparison to control group or to regular cases [P < 0.05]. No significant difference was found between alpha-1-antitrypsin levels in serum of parents of cases and that of parents of controls. Further, no correlation was found between cases or controls and their parents regarding serum alpha-1-antitrypsin levels. We conclude that alpha-1-antitrypsin might have a role in the development of trisomy 21 through its effect on mitotic cell division by unknown mechanism. Alpha-1-antitrypsin level in parents of cases might be defiicient only in the germ cell and mitotic non disjunction could happen upon an originally euploid zygote. As mosaic chromosomal abnormalities are of postzygotic origin, positive results observed in mosaic cases suggest that mitotic non disjunction could be the result of some unknwon influence of certain protease phenotypes upon a euploid zygote