Immunofluorescence Analysis and Diagnosis of Primary Ciliary Dyskinesia with Radial Spoke Defects.

American journal of respiratory cell and molecular biology 2015 Oct

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Primary ciliary dyskinesia (PCD) is a genetically heterogeneous recessive disorder caused by several distinct defects in genes responsible for ciliary beating, leading to defective mucociliary clearance often associated with randomization of left/right body asymmetry. Individuals with PCD caused by defective radial spoke (RS) heads are difficult to diagnose owing to lack of gross ultrastructural defects and absence of situs inversus. Thus far, most mutations identified in human radial spoke genes (RSPH) are loss-of-function mutations, and missense variants have been rarely described. We studied the consequences of different RSPH9, RSPH4A, and RSPH1 mutations on the assembly of the RS complex to improve diagnostics in PCD. We report 21 individuals with PCD (16 families) with biallelic mutations in RSPH9, RSPH4A, and RSPH1, including seven novel mutations comprising missense variants, and performed high-resolution immunofluorescence analysis of human respiratory cilia. Missense variants are frequent genetic defects in PCD with RS defects. Absence of RSPH4A due to mutations in RSPH4A results in deficient axonemal assembly of the RS head components RSPH1 and RSPH9. RSPH1 mutant cilia, lacking RSPH1, fail to assemble RSPH9, whereas RSPH9 mutations result in axonemal absence of RSPH9, but do not affect the assembly of the other head proteins, RSPH1 and RSPH4A. Interestingly, our results were identical in individuals carrying loss-of-function mutations, missense variants, or one amino acid deletion. Immunofluorescence analysis can improve diagnosis of PCD in patients with loss-of-function mutations as well as missense variants. RSPH4A is the core protein of the RS head.

Citation

Adrien Frommer, Rim Hjeij, Niki T Loges, Christine Edelbusch, Charlotte Jahnke, Johanna Raidt, Claudius Werner, Julia Wallmeier, Jörg Große-Onnebrink, Heike Olbrich, Sandra Cindrić, Martine Jaspers, Mieke Boon, Yasin Memari, Richard Durbin, Anja Kolb-Kokocinski, Sascha Sauer, June K Marthin, Kim G Nielsen, Israel Amirav, Nael Elias, Eitan Kerem, David Shoseyov, Karsten Haeffner, Heymut Omran. Immunofluorescence Analysis and Diagnosis of Primary Ciliary Dyskinesia with Radial Spoke Defects. American journal of respiratory cell and molecular biology. 2015 Oct;53(4):563-73