Differential expression of salivary (Amy1) and pancreatic (Amy2) human amylase loci in prenatal and postnatal development.

The age-dependent development of alpha-amylase expression in utero and during the first two years of life is reported. Separation of salivary and pancreatic amylase isozymes in a discontinuous buffered sheet polyacrylamide electrophoretic system, with subsequent densitometry, provides a reliable semiquantitative method of estimating the proportions of salivary and pancreatic amylases in urine and amniotic fluid samples. In the newborn the predominant amylase isozymes seen in the urine are of salivary origin. As the child ages the level of amylase in the urine rises and an increase in the proportion of pancreatic amylase isozymes occurs. Amniotic fluids of late first and early second trimester pregnancies contain salivary isozymes. None of the amniotic fluid samples examined has pancreatic amylase isozymes. These data reflect a differential development of the expression of the two amylase approaches adult levels by 16 months of age. Conversely, the salivary (Amy1) locus is expressed as early as 18 weeks of gestation and remains relatively constant with but a small increase in salivary amylase (units/ml) activity during early development, as the total amylase activity approaches adult values.