Prenatal diagnosis of alpha 1-antitrypsin deficiency by analysis of fetal blood obtained at fetoscopy.
Two women had each borne a child who had alpha 1-antitrypsin (alpha 1AT) deficiency Pi ZZ and who developed liver cirrhosis. In subsequent pregnancies, the women requested prenatal diagnosis. Samples of blood from the two fetuses were obtained at fetoscopy. In a control group of five Pi MM fetuses aborted by hysterotomy, the mean alpha 1AT level was 0.73 g/liter. Of the two fetuses at risk, one had an alpha 1AT concentration calculated as 0.60 g/liter, i.e., within the Pi MZ range. The electrofocusing pattern indicated a heterozygous Pi MZ phenotype which was confirmed at birth. The other fetus at risk had a markedly decreased concentration of alpha 1AT, 0.06 g/liter. Electrofocusing showed a homozygous Pi ZZ phenotype. Analysis of blood from the abortus confirmed these findings and thus the diagnosis of alpha 1AT deficiency. Speculation Most of the alpha 1-antitrypsin in amniotic fluid is derived from the mother. It therefore appears that the only possible way of making a prenatal diagnosis of alpha 1-antitrypsin deficiency is by examination of blood from the fetus. One fetus examined in the present study had an abnormal Z-pattern. This abnormality may indicate a disturbance of fetal liver function already in utero.