• Amelia Shoemark, Eduardo Moya, Robert A Hirst, Mitali P Patel, Evelyn A Robson, Jane Hayward, Juliet Scully, Mahmoud R Fassad, William Lamb, Miriam Schmidts, Mellisa Dixon, Ramila S Patel-King, Andrew V Rogers, Andrew Rutman, Claire L Jackson, Patricia Goggin, Bruna Rubbo, Sarah Ollosson, Siobhán Carr, Woolf Walker, Beryl Adler, Michael R Loebinger, Robert Wilson, Andrew Bush, Hywel Williams, Christopher Boustred, Lucy Jenkins, Eamonn Sheridan, Chung Eddie M K EMK Population, Policy and Practice Programme, University College London, UCL Great Ormond Street Institute of Child Health, London, UK., Christopher M Watson, Thomas Cullup, Jane S Lucas, Priti Kenia, Christopher O'Callaghan, Stephen M King, Claire Hogg, and Hannah M Mitchison.
• Department of Paediatric Respiratory Medicine, Royal Brompton and Harefield NHS Trust, National Heart and Lung Institute, London, UK.
• Thorax. 2018 Feb 1; 73 (2): 157-166.

RationalePrimary ciliary dyskinesia is a genetically heterogeneous inherited condition characterised by progressive lung disease arising from abnormal cilia function. Approximately half of patients have situs inversus. The estimated prevalence of primary ciliary dyskinesia in the UK South Asian population is 1:2265. Early, accurate diagnosis is key to implementing appropriate management but clinical diagnostic tests can be equivocal.ObjectivesTo determine the importance of genetic screening for primary ciliary dyskinesia in a UK South Asian population with a typical clinical phenotype, where standard testing is inconclusive.MethodsNext-generation sequencing was used to screen 86 South Asian patients who had a clinical history consistent with primary ciliary dyskinesia. The effect of a CCDC103 p.His154Pro missense variant compared with other dynein arm-associated gene mutations on diagnostic/phenotypic variability was tested. CCDC103 p.His154Pro variant pathogenicity was assessed by oligomerisation assay.ResultsSixteen of 86 (19%) patients carried a homozygous CCDC103 p.His154Pro mutation which was found to disrupt protein oligomerisation. Variable diagnostic test results were obtained including normal nasal nitric oxide levels, normal ciliary beat pattern and frequency and a spectrum of partial and normal dynein arm retention. Fifteen (94%) patients or their sibling(s) had situs inversus suggesting CCDC103 p.His154Pro patients without situs inversus are missed.ConclusionsThe CCDC103 p.His154Pro mutation is more prevalent than previously thought in the South Asian community and causes primary ciliary dyskinesia that can be difficult to diagnose using pathology-based clinical tests. Genetic testing is critical when there is a strong clinical phenotype with inconclusive standard diagnostic tests.© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

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