Alpha-1-antitrypsin deficiency associated with the Mattawa variant.

The most common deficiency alleles for alpha-1-antitrypsin deficiency (AATD) are PiS and PiS, but there are also other deficiency variants. This case report describes the first two cases of AATD detected in Spain resulting from the combination of a null Mattawa allele with a normal PIM, and a rare Mmalton. Both cases were initially diagnosed as PiMM by isoelectric focusing (IEF), but the low serum AAT values led us to suspect the existence of rare deficiency alleles that were undetectable using this technique, and to performing molecular analysis of the gene, which provided the correct diagnosis. Inconsistencies between serum AAT values and the phenotype should make one suspect the existence of one of these rare alleles.