P9 Genetic variants in bronchiectasis- a proof of concept study

Bronchiectasis is a clinical syndrome linked with recurrent infections and dysregulation of airway epithelial defences. Prior data suggesting cystic fibrosis genetic mutations are more common in bronchiectasis but there are few other data in bronchiectasis. Recently familial cases of bronchiectasis have led to the identification of activated PI3 kinase syndrome as a genetic cause and bronchiectasis is a manifestation of a number of related immunodeficiencies. Recently a multisite Bronchiectasis collaborative with biobank (www.bronch.ac.uk) has been developed. Future genetics studies may be conducted from the biobank pending appropriate funding. We studied to investigate the feasibility of using frozen whole blood and have chosen to study PI3kinase and other immune regulatory genes in any suspected aetiology of bronchiectasis. Methods 220 unselected adult patients with bronchiectasis were recruited in Newcastle for a single centre study. Using the BronchUk protocol whole frozen blood from a single centre biobank was then used for DNA extraction from 46 patients randomly selected patients. We used a proprietary kit (Qiagen) and used 3 mls of whole blood. The DNA was then quantified using a nanodrop and then studied using a multiplex PCR approach studying PIK3CD, PIK3R1, STAT1, STAT3, CTLA4 and NFKB1 (using in house primers). Positive and negative controls were included. Results Of the 46 patients studied the mean age was 63.7 years and M:F gender was 18:28 and average FEV1% predicted was CCC%. Good DNA extraction was possible from the archived biobank samples (average 28 ng/ul). All patients yielded DNA suitable for pCR amplification. None of the patients samples demonstrated known pathogenic variants in the investigated genes. The STAT1 c.633+6Tu003eA and the STAT3 c.551–4Gu003eA heterozygote variants detected in one patient each have an allele frequency in the general population that favour classification as a polymorphism. Conclusions We have shown that BronchUK methodology archiving frozen whole blood can be used to test for immune dysregulation genes in biobanked samples. Overall, the frequency of primary immunodeficiencies in unselected patients with bronchiectasis appears to be low. Laregr sample sizes studied with broader gene panels including CFTR are needed Acknowledgements MRC funding to Bronch UK, Unrestricted grant to Prof Ehl from UCB.