Primary ciliary dyskinesia in a Japanese woman caused by a novel RSPH4A variant

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterized by ciliary dysfunction. We report the case of a 50-year-old Japanese woman with chronic cough, sinusitis, hearing loss, and bronchiectasis. High-speed video analysis of the nasal mucosa revealed reduced ciliary beat frequency and amplitude. Electron microscopy revealed normal cilia mixed with cilia lacking central microtubules. Genetic testing identified a homozygous RSPH4A variant (NM_001010892.3: c.1484C > A). RSPH4A variants account for approximately 3-4 % and <2 % of cases of PCD worldwide and in East Asia, respectively. This is the third reported case in Japan and the first reported case of the c.1484C > A variant.