The Palestinian primary ciliary dyskinesia population: first results of the diagnostic, and genetic spectrum

Abstract

Diagnostic testing for primary ciliary dyskinesia (PCD) started in 2013 in Palestine. We aimed to describe the diagnostic, genetic, and clinical spectrum of the Palestinian PCD population.

Individuals with symptoms suggestive of PCD were opportunistically considered for diagnostic testing: nasal nitric oxide (nNO) measurement, transmission electron microscopy (TEM), and/or PCD genetic panel or whole exome testing. Clinical characteristics of those with a positive diagnosis were collected close to testing including FEV₁ GLI z-scores, and BMI z-scores.

Sixty-eight individuals had a definite positive PCD diagnosis, 31 confirmed by genetic and TEM results, 23 by TEM results alone, and 14 by genetic variants alone. Forty-five individuals from 40 families had seventeen clinically actionable variants, and 4 had variants of unknown significance in 14 PCD-genes. CCDC39, DNAH11, and DNAAF11 were the most commonly mutated genes. 100% of variants were homozygous. Patients had median age of 11.2 years at diagnosis, were highly consanguineous (93%) and 100% of Arabic descent. Clinical features included persistent wet cough (99%), neonatal respiratory distress (84%), and situs inversus (43%). Lung function at diagnosis was already impaired (FEV₁ z-score median −1.90 (−5.0 to 1.32)) and growth was mostly within the normal range (z-score mean= −0.36 (−3.03 to 2.57). 19% individuals had finger clubbing.

Despite limited local resources, detailed geno- and phenotyping forms the basis of one of the largest national PCD populations globally. There was notable familial homozygosity within the context of significant population heterogeneity.