Lewis and ABH substances in amniotic fluid obtained by amniocentesis.

Abstract

Extract: When eight amniotic fluid samples obtained by transabdominal amniocentesis at various ages of gestation (15–38 weeks) were tested, Lewis substances were present in considerable concentration as early as 15 weeks of gestation. The amniotic Lewis substances found corresponded to the Lewis and secretor phenotypes of the fetus ascertained by determination of the erythrocyte and salivary phenotypes of the mother-infant pairs after delivery. These findings indicate strongly that the amniotic Lewis substances are exclusively of fetal origin. Although not conclusive, the data also indicate that the amniotic ABH substances are the expression of the fetal ABH and secretor status. Speculation: This preliminary study shows that the fetal Lewis and secretor phenotype can be determined antenatally by amniocentesis. This information could be clinically significant in the prenatal detection of hereditary conditions exhibiting linkage to the Lewis and secretor loci. In further research on this subject, Lewis phenotypes of erythrocytes in infants should be determined at appropriate postnatal age with due consideration for the maturation process and differential tissue expressivity of the Lewis and secretor gene systems. Amniotic fluid samples should be obtained preferably by transabdominal amniocentesis to avoid contamination by maternal secretions and saliva from infants should be obtained several days postnatally.