Screening for α1-antitrypsin deficiency in the pneumologist’s office using a dried blood spots kit: promising first results

Introduction: Although hepatic and pulmonary consequences of severe α1-antitrypsin (A1AT) deficiency have been recognised for over 50 years, this hereditary condition remains under-diagnosed. A diagnostic kit (Apha-SpotTM) has thus been developed by LFB to enable quantitation and phenotyping of A1AT using dried blood spots (Balduyck et al. Ann Biol Clin 2014; 72:689-704). Aims and objective: To assess the performance of the Alpha-SpotTM kit over the first 9 months of use. Methods: The study was conducted by community-based chest physicians. The diagnostic kit contained material for capillary blood collection and spotting it on filter paper, conditioning and dispatching to the screening laboratories. On the sample card a space was devoted for providing patient informations. Results: Two hundred and forty blood samples received between March and December 2016. Due to incomplete coverage of circles drawn on the filter paper, 234 could be assayed and 227 phenotyped or genotyped. Mean age was 57,3 years, 66% were men and 57% non-smokers. Clinical history was documented for 197 patients: 144 had emphysema. The mean A1AT concentration was 1.21 ± 0.44 g/L. The observed phenotypes were 154 PiM, 28 PiMS, 1 PiS, 24 PiMZ, 4 rare deficient heterozygous phenotypes (PiFM, PiMMmalton, PiMMprocida, PiMQ0) and 16 (7%) severely deficient phenotypes (10 PIZ, 5 PiSZ and 1 PIMmalton). Conclusions: Although further instructions should be provided to improve the quality of sample preparation, initial results indicate that this kit represents a promising diagnostic test for A1AT deficiency in routine consultations of pneumologists from community practice.