A 25-year-old Japanese woman suffered from repeated respiratory tract infections. Because of her characteristic medical history and imaging findings, we suspected primary ciliary dyskinesia (PCD) and performed a transbronchial biopsy. The biopsy revealed complex abnormalities of the ciliary structure including cleavage of the B-subfibers observed by transmission electron microscopy analysis and the complete loss of ciliary motion by video analysis. Genetic examinations to diagnose PCD have progressed in recent years. However, in this case, the well-known genetic mutations in causal genes of PCD were not detected via whole-exome sequencing of the blood. Cleavage of the B-subfibers in patients with PCD has never been reported. This case appears to be the first report of this PCD subtype in humans.
Keywords: B‐subfiber; genetic mutation; immotile cilia; primary ciliary dyskinesia; transmission electron microscope.