Laboratory testing for AATD | | |
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All individuals with COPD regardless of age or ethnicity; all individuals with unexplained chronic liver disease; all individuals with necrotising panniculitis, granulomatosis with polyangiitis, or unexplained bronchiectasis should be tested for AATD Parents, siblings and children, as well as extended family of individuals identified with an abnormal gene for AAT, should be provided genetic counselling and offered testing for AATD For family testing after a proband is identified, AAT level testing alone is not recommended, because it does not fully characterise disease risk from AATD For diagnostic testing of symptomatic individuals, genotyping for at least the S and Z alleles is recommended Advanced or confirmatory testing should include Pi-typing, AAT level testing and/or expanded genotyping
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Quantitative determination of AAT levels in blood is a crucial first test to identify AATD Quantitative deficiency must be supported by qualitative tests to identify the genetic mutation(s) causing AATD Protein phenotyping by isoelectric focusing identifies variants where AAT is present in the sample including the rarer variants F, I and P, etc. Genotyping allows a rapid and precise identification/exclusion of S and Z alleles and other variants, where specific primers are available Gene sequencing remains necessary for those cases where a null variant or a deficient variant other than Z or S is suspected Testing of relatives of identified patients should be considered after appropriate counselling Genetic testing should be carried out only after informed consent is given and in accordance with the relevant guidelines and legislation
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Pulmonary function testing | | |
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Initial evaluation with complete lung function testing is recommended Annual follow-up of adults with at least a spirometry test is recommended Since the lung disease associated with AATD often starts as purely parenchymal destruction, more complete pulmonary function testing (including measures of diffusing capacity) may be considered
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Chest CT scanning | | |
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In newly diagnosed patients who are symptomatic and/or have abnormal pulmonary function testing, a baseline CT scan of the chest is recommended Serial chest CT scanning to monitor progression of disease is not recommended
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Lung densitometry, as performed in observational cohort studies and randomised clinical trials, is the most sensitive measure of emphysema progression The correlation between change in lung density and any short-term change in measures of pulmonary function is weak; however, in the longer term, CT lung density decline correlates with reduction in FEV1 and health status The role of CT in the follow-up of patients in routine clinical practice requires further validation
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