Phosphofructokinase activity in normal diploid mice during development and in trisomy 16 fetal mice.

Although several of the genes mapped to human chromosome 21 have been assigned to mouse chromosome 16, it has not yet been possible to do this for the gene for the phosphofructokinase liver type subunit (PFKL). The goal of this study was to determine if there is a 1.5-fold increase of the PFK activity in fetal trisomy 16 mice, which, if present, would be indicative of a gene dosage effect. However, rather than an increase, an almost 100% decrease of the mean PFK activity was observed in fetal trisomy 16 liver at both 14 and 17 days of gestation when compared to littermate controls. This is the first biochemical abnormality detected in trisomy 16 fetal liver. In contrast, no significant differences in the mean PFK activity in homogenized whole fetus or brain trisomy 16 and diploid controls were observed. A developmental maturational effect of the PFK activity was observed in fetal liver from normal diploid mice, with a 3-fold increase of the activity from day 14 to day 18 of gestation and a further 2-fold increase to adulthood. The decreased PFK activity in fetal trisomy 16 liver may therefore be the result of delayed maturation of the liver in trisomic fetuses.