Med. J. Cairo Univ., Vol. 60, No. 1: 87 - 95 , 1992 Alpha-One Antitrypsin Phenotypes in Chest Diseases in Infants and Children ZINAB RADWAN, M. D.; SAMIHA SAMUEL, M.D.; NERMIN BAHGAT, M.D.; IBRAHIM RADWAN, M.D.; MOHAMED HANI HAFEZ, M.D. and MOHAMED SABRY SALIM, M.D. The Pediatric, Chemical Pathology, Internal Medicine and Chest Departments, Faculties of Medicine, Cairo, Al-Azhar and Banha Universities Abstract Most of the previous studies were done on Ihe relation between alphal- anlilrypsin (ALAT) and pulmonary diseases in adulthood. In the present work, we studied 91 infants and children (52 males and 40 females) suffering from 5 common chest diseases : Chronic bronchitis (25 patients), bronchieclasis (12 patients), bronchial asthma (20 patients), bronchopneumonia (15 patients) and pulmonary TB (20 patients). Bronchial asthma patients were subdivided into atopic (14 cases) and non atopic (6 cases) according to the results of IgE and allergic skin test. 30 normal children were taken as controls. All patients and controls were subjected to chest radiographs, CBCt ESR, quantitative determination of scrum ALAT by radial immunodillusion method and ALAT phenotyping by immunofixation eleclrophoresis. A second serum ALAT determination alter 3 weeks of treatment was carried in chronic bronchitis, bronchopneumonia and bronchial asthma groups. It was done after 6 months in tuberculous patients. Serum ALAT in all patient groups, with the exception of bronchial asthma, was significantly higher than control at the initial estimation. As ALAT is one of the acute phase reactants it rises in active chest diseases. After treatment these high levels dropped to normal. In asthmatic patients, there is significant decrease of serum ALAT, both in atopic and non atopic cases. But the level was higher in patients with associated chest infection than in those without. As regards ALAT phenotyping the MM phenotype was the commonest. It was found in all controls, in 84% of chronic bronchitis, 75% of bronchiectasis, 86.6% of bronchopneumonia, 85% of TB. In asthmatics other Pi variants (MS, M/., SS), known to be ALAT deficient formed the majority of cases. Among the 92 patients studied, 22.23% had other phenotype variants than the PiM. These PiM were heterozygous deficient in ALAT and presented as recurrent chest infections or bronchial asthma. 87