Alpha1-antitrypsin deficiency with M-like phenotype'

SUMMARY A patient with a low serum concentration of a1-antitrypsin (0-1 g/l) but with an M-like phenotype is described. Her parents and 2 sibs have a PiM phenotype, but all except the father have approximately half-normal levels of cx1-antitryspin: The M-like variant apparently cannot be dis-tinguished from M-a1-antitrypsin, when it occurs with M in heterozygotes. The proposita has severe airways obstruction and emphysema, and her father has moderate chronic obstructive pulmonary disease. The mother and 2 sibs are healthy. Since the first descriptions of a,-antitrypsin deficiency associated with obstructive lung disease and em-physema by Eriksson (1964, 1965) many cases of this syndrome have been reported. Most of these patients are homozygous for the allele PiZ. A few other types, however, have been described: Talamo et al. (1973) reported a patient with no detectable al-antitrypsin in his serum. Cox (1975), Lieberman et al. (1976) and Martin et al. (1975) have found patients with low concentrations of al-antitrypsin which was of the same or similar electrophoretic mobility as the M protein. In this report, we describe a patient with a low serum level of a1-antitrypsin whose phenotype how-ever, was different from Z but similar to M. Subjects and methods FAMILY The proposita is a 38-year-old woman. At the age of 12 years she had pneumonia. She never smoked and had no chronic bronchitis. At the age of 20 years, she noticed dyspnoea on exertion; a chest x-ray film at that time was interpreted as showing emphysema of the right lung, and an electrocardiogram showed signs of right ventricular hypertrophy. At the present examination, she was dyspnoeic at rest. A chest x-ray film showed a decrease in vascular markings of the right lung and at the left base. A lung scintigram using '25l-labelled macroaggregated albumin showed defects in perfusion over the whol