Immunostaining and Ciliary Movement Analysis in Primary Ciliary Dyskinesia With a Homozygous Deletion Involving Exons 1–4 of <i>DRC1</i> : A Case Report

ABSTRACT Primary ciliary dyskinesia (PCD) presents various clinical manifestations, including bronchiectasis, chronic sinusitis, situs inversus, and infertility. PCD is diagnosed through multiple methods, including transmission electron microscopy (TEM), high‐speed video microscopy analysis (HSVA), immunofluorescence (IF), and genetic testing. Recent reports show that a homozygous deletion involving exons 1–4 of DRC1 is common in Japanese patients with PCD. We report the case of a 29‐year‐old male without situs inversus previously diagnosed with diffuse panbronchiolitis, who underwent PCD testing. TEM appeared almost normal, and HSVA showed motile cilia with reduced amplitude. Genetic testing revealed a homozygous deletion involving exons 1–4 of DRC1 . Due to lack of a suitable DRC1 antibody for IF, we used the DRC3 antibody as in previous studies. IF showed the absence of DRC3 in the cilia, suggesting a DRC1 deletion affects DRC3 localization in the cilia. To the best of our knowledge, this case represents one of the earliest reports to perform IF and ciliary movement analysis in PCD with a homozygous deletion involving exons 1–4 of DRC1 .