Studies of alpha1-antitrypsin in amniotic fluid, meconium and cord serum of a homozygote newborn infant. pp. 107-22.

Cord serum, amniotic fluid and meconium of a newborn from a heterozygote 
(PiZZ) mother were investigated. In the newborn infant the diagnosis of 
homozygote (PiZZ) deficiency of alpha1-antitrypsin could be established in cord serum 
at the time of delivery. Trypsin inhibitory capacity (TIC) and alpha1-antitrypsin 
(AT) in cord serum were in the range of adult homozygotes. 
By means of crossed immunoelectrophoresis exclusively, the phenotypic alleles ZZ were 
demonstrable. This excludes the possibility of materno-fetal transfer of alpha1-antitrypsin. In 
infant amniotic fluid extremely low antiprotease-activity and substantially no alpha1-antitrypsin was 
found, whereas in normal samples the TIC is 3% to 6% 
of the cord serum values and the AT 1.2% to 4% 
of cord serum concentration. Our data suggest that a major component 
of TIC and AT in normal amniotic fluid derive from the 
fetus. In normal meconium we detected TIC and AT in concentrations 
increasing proportionally to the total protein content. The inhibitory capacity of 
AT in meconium expressed in mg trypsin inhibited per mg alpha1-antitrypsin 
however is 80% less than serum alpha1-antitrypsin. No correlation exists with 
the free tryptic activity of meconium. The AT of an PiZZ 
infant is clearly diminished when referred to fresh weight, whereas meconia 
from three cystic fibrosis newborns screened by the BM test had 
extremely high concentrations. Estimation of TIC and AT in meconium is 
regarded as a useful approach for screening on homozygote alpha1-antitrypsin deficiency. 
The exact diagnosis however can only be established by phenotyping the 
alleles. In cystic fibrosis the high protein content of meconium is 
accompanied by increased alpha1-antitrypsin levels. 