[COPD characteristics in subjects carrying the rare alpha-1 antitrypsin variant PIMMmalton].

Introduction: Several studies have investigated the clinical feature of COPD in subjects carrying the common alpha-1 antitrypsin deficiency mutations PIS and PIZ. However, there are few data on COPD due to rarer deficient variants. In this study, we aimed to explore the features of COPD in subjects carrying the PIMMmalton mutation, which is the most prevalent alpha-1 antitrypsin variant in Tunisia.

Material And Methods: Five individuals, heterozygous for PIMMmalton were analyzed and compared to 97 non-deficient COPD patients. Demographic data as well as clinical and functional outcomes from subjects were collected. Blood gases and plasma alpha-1 antitrypsin levels were recorded.

Results: PIMMmalton subjects did not show any significant difference in terms of predicted FEV1 (35±13.2%), predicted forced vital capacity (34.2±9.6%) and FEV1 decline (148.6±114mL/year) compared to usual COPD patients (respectively 41.7±17.2%, P=0.500; 43.8±18.8%, P=0.300; 197.9±191mL/year, P=0.800). However, PaO2 was significantly reduced in PIMMmalton subjects (58.8±4.0mmHg) compared to usual COPD (69.9±10.6mmHg; P=0.029) and those patients with chronic bronchitis and centrolobular emphysema (71.0±10.9mmHg; P=0.038).

Conclusion: PIMMmalton subjects were significantly hypoxic, similar to that observed in PiZZ homozygous rather than observed in heterozygous individuals.