Cytochemical and biochemical studies on neutrophil alkaline phosphatase in parents of trisomy 21 children

A study of karyotypes and neutrophil alkaline phosphatase (NAP) was carried out for 66 parents (33 couples) of trisomy 21 children and for 60 control parents (30 couples). Enzyme activity was determined simultaneously by biochemical and cytochemical techniques. In the mothers of trisomy 21 children we found: (a) by biochemical techniques, a significant increase of NAP activity in polymorphonuclear leukocyte (PMN) homogenates (P<0.01) and a lower supernatant/pellet ratio (P<0.01); (b) by cytochemical techniques (with or without thermal and urea treatments) NAP activity was significantly higher (P<0.001) than in control mothers; in the fathers, the two techniques gave normal NAP activity results.