Required for the maintenance and formation of cilia. Fishes display cysts in the glomerular-tubular region of the kidney similar to cystic kidney disease. Knockdown of the gene with 2 morpholino oligonucleotides leads to ventral body-axis curvature, formation of kidney cysts, otolith defects, and hydrocephalus, as well as cartilage defects of the craniofacial skeleton. Knockdown of the gene in a rhodopsin-GFP transgenic line demonstrates that the level of rhodopsin-GFP is lower in ift172 morphants than controls, suggesting retinal degeneration. Scanning electron microscopy of the olfactory placode reveales ciliogenesis defects in morphants, including shortened and truncated cilia. Belongs to the IFT172 family.