A 39-year-old female patient, an ex-smoker with an 8–pack-year smoking history and severe pulmonary emphysema of early onset, received a diagnosis of α1-antitrypsin (AAT) deficiency and proved to be a carrier of a new deficient variant, Ybarcelona, derived from the normal M1 variant with two substitutions: one in exon III and the other in exon V. AAT genotype of eight members of the same family and study of lung function of the index case and family members at baseline and after 6 years of follow-up were performed. Five subjects were PiYM, with intermediate serum AAT concentrations and normal pulmonary function. No changes were observed over 6 years in pulmonary function of the PiYM patients who were nonsmokers; however, the PiYY index case presented worsening of pulmonary function with FEV1 of 33%. The heterozygotes PiYM have AAT concentrations similar to the PiMZ and, at 6 years, the nonsmokers presented no worsening in pulmonary function. The risk associated with this variant in its heterozygous form may be similar to that described for PiMZ.