An association between a genetically determined deficiency of the serum enzyme al antitrypsin and pulmonary emphysema is now well established. Serum antitryptic activity was measured in 103 patients suspected of having emphysema. Eighty-seven fulfilled the diagnostic criteria for emphysema and, of these, 16 had deficient levels, 5 had intermediate levels, and 66 had normal levels. The results of clinical, radiographic, and physiological studies in each group were then compared. Characteristic features noted in the deficient group included onset of dyspnoea during the third or fourth decades and uniformly symmetrical radiographic lower zone involvement. Other factors such as sex distribution, cigarette smoking, and chronic bronchitis are discussed.Sixty-eight relatives of the 16 patients with deficient levels were also studied. The findings in these are compatible with an autosomal recessive mode of inheritance although difficulties in identifying the heterozygous state were encountered. Six relatives had deficient levels and of these three had emphysema.Emphysema is most commonly diagnosed in men with chronic bronchitis in the fifth or sixth decades (Talamo, Blennerhassett, and Austen, 1966 This paper presents the findings in a selected series of patients attending the Brompton Hospital with chronic respiratory disease in whom levels of serum antitryptic activity were estimated.
DIAGNOSIS OF EMPHYSEMAEmphysema is defined on an anatomical basis as a disease characterized by structural changes in the lung causing increase, beyond the normal range, in the size of air spaces distal to terminal bronchioles (Scadding, 1969). In life, however, histopathological specimens are not usually available and therefore the diagnosis depends on clinical, radiological, and physiological criteria. For the purpose of this study the following radiological and physiological criteria were adopted, the former having been shown to be strongly correlated with moderate to severe emphysema (Reid and Millard, 1964): 1. Radiological (Simon, 1964).