Prenatal diagnosis of alpha 1-antitrypsin deficiency by restriction fragment length polymorphisms, and comparison with oligonucleotide probe analysis.

Prenatal diagnosis of sixteen pregnancies at risk for alpha 1-antitrypsin (AAT) deficiency has been achieved by restriction fragment length polymorphism (RFLP) analysis and compared with diagnostic results using hybridisation of M and Z specific oligonucleotides. The results of both tests were in accord for all samples, although under routine laboratory conditions RFLP analysis was more reliable. Because RFLP analysis does not depend on the type of mutation it was possible, in the product of an MZ and SZ mating, to predict an MZ rather than an MS phenotype using the RFLP method. The strong linkage dysequilibrium between an AvaII RFLP and the Z allele increases its diagnostic usefulness. Even so it seems reasonable to use oligonucleotide analysis in families where no siblings are available for comparison. In all other situations RFLP analysis is as accurate and reliable as oligonucleotide analysis and is technically easier, making it the preferred means of diagnosis for informative kindreds.