Small airways disease in patients with alpha-1 antitrypsin deficiency

Recommendations for the diagnosis and treatment of alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is a relatively rare genetic disorder, inherited in an autosomal codominant manner, that results in reduced serum AAT concentrations, with a consequent reduction in antielastase activity in the lungs, as well as an increased risk of diseases such as pulmonary emphysema, liver cirrhosis, and necrotizing panniculitis. It results from different mutations in the SERPINA1 gene, leading to changes in the AAT glycoprotein, which can alter its concentration, conformation, and function. Unfortunately, underdiagnosis is quite common; it is possible that only 10% of cases are diagnosed. The most common deficiency is in the Z variant, and it is estimated that more than 3 million people worldwide have combinations of alleles associated with severe AATD. Serum AAT concentrations should be determined, and allelic variants should be identified by phenotyping or genotyping. Monitoring lung function, especially through spirometry, is essential, because it provides information on the progression of the disease. Although pulmonary densitometry appears to be the most sensitive measure of emphysema progression, it should not be used in routine clinical practice to monitor patients. In general, the treatment is similar to that indicated for patients with COPD not caused by AATD. Exogenous administration of purified human serum-derived AAT is the only specific treatment approved for AATD in nonsmoking patients with severe deficiency (serum AAT concentration of < 57 mg/dL or < 11 µM), with evidence of functional loss above the physiological level.

Alpha-1 antitrypsin deficiency associated with increased risks of skin cancer, leukemia, and hepatic cancer: A nationwide cohort study

BACKGROUND

α1-Antitrypsin deficiency is characterized by elevated elastase activity and excessive elastin degradation, which may impact cancer development and progression. We tested the hypothesis that individuals with α1-antitrypsin deficiency have increased susceptibility to cancer in the Danish population.

METHODS

In a nationwide nested study, we identified 2702 individuals with α1-antitrypsin deficiency and 26,750 control subjects without α1-antitrypsin deficiency matched on age, sex, and municipality. We recorded admissions due to cancer as outcomes during a median follow-up of 62 years.

RESULTS

Individuals with α1-antitrypsin deficiency versus control subjects had an increased hazard of skin cancer (2.18, 95%CI: 1.81-2.63), leukemia (1.76, 1.12-2.79), liver cancer (3.91, 2.23-6.85), and cancer overall (1.25, 1.13-1.38). Corresponding hazard ratios when the entire Danish population was used as control group were 3.02 (2.55-3.58), 1.83 (1.19-2.81), 4.46 (2.74-7.28), and 1.45 (1.31-1.59). When the analysis was stratified according to comorbidities, the hazard for skin cancer was higher in those with chronic obstructive pulmonary disease (COPD) (3.59, 2.60-4.95) and skin disease (2.93, 2.19-3.92) but remained elevated in those without any of these diseases. Hazards for skin cancer in individuals with α1-antitrypsin deficiency were similar when stratified by liver cirrhosis and ischemic heart disease (ps for interaction: ≥0.76). Hazards for liver cancer in individuals with α1-antitrypsin deficiency versus control subjects were similar when stratified according to liver cirrhosis, COPD, skin disease, and ischemic heart disease (ps for interaction: ≥0.13).

CONCLUSION

Individuals with α1-antitrypsin deficiency have increased risks of skin cancer, leukemia, and liver cancer in the Danish population.

Alpha-1 Antitrypsin Gene Variants in Patients without Severe Deficiency Diagnosed with Pulmonary Emphysema on Chest CT

Introduction

Although pulmonary involvement due to alpha-1 antitrypsin (AAT) deficiency has been widely described, most studies focus on the genotypes causing severe deficiency (<60 mg/dL).

Objective

The aim of this study was to analyze the prevalence of the different AAT gene variants that do not cause severe deficiency in patients with pulmonary emphysema diagnosed by thoracic computed tomography (CT). Furthermore, we assessed the risk associated with a non-severe decrease in AAT values in the pathogenesis of emphysema.

Methods

Case-control study design that included patients who had a CT scan available of the entire thorax. In total, 176 patients with emphysema (cases) and 100 control subjects without emphysema were analyzed.

Results

The prevalence of variants was higher among cases (25.6%; 45/176) than controls (22%; 22/100), although the difference was not statistically significant (P=0.504) when analyzed globally. In the control group, all the variants detected were MS. Excluding this variant, statistically significant differences were observed in the remaining variants (MZ, SS and SZ). Only 18% of the controls (all MS) presented values below our limit of normality, and all had values very close to the reference value (90 mg/dL). In contrast, 76% of patients with the other variants presented pathological levels. In a logistic regression model, both smoking and a non-severe reduction in AAT (60 to 90 mg/dL) increased the probability of emphysema.

Conclusion

Our study confirms an association between certain variants in the alpha-1 antitrypsin gene that do not cause severe deficiency and the presence of pulmonary emphysema. This association with variants that are associated with reductions in serum AAT values is statistically significant and independent of smoking habit.