Number of nexin links detectable at standard electron microscopy of normal human nasal cilia and at nexin link deficiency

Abstract

Background: Eleven years ago we had described three patients with missing nexin links as a possible cause of primary ciliary dyskinesia (PCD). The assumption was substantiated last year by finding a mutation in these patients. Materials and Methods: We counted the nexin links, inner (IDA) and outer (ODA) dynein arms and microtubuli in each of, if possible, 50 cilia in 41 patients with normal cilia, 4 patients with deficiency of nexin links only and 4 with deficiency of nexin links and IDA. Results: In the control group the median number of nexin links was 4.5 per cilium, range 3.4–5.3. In the second group the mean numbers of nexin links per cilium were 1.1–1.4, in the third group 0.8–1.2, per patient. The median number of IDA was in the control group 4.2, range 3.3–5.2. In groups 2 and 3 the numbers were 3.0–3.5 and 0.2–1.0, respectively. Numbers of ODA were normal in all groups. Conclusions: It is possible to reliable count the number of nexin links in nasal human cilia and to distinguish cases with missing nexin links from normal controls.