Expanding the phenotypic spectrum of IFT81: Associated ciliopathy syndrome

Short-rib polydactyly syndromes are a heterogeneous group of disorders characterized by narrow thorax with short ribs, polydactyly and often other visceral and skeletal malformations. To date there have only been six reported patients with homozygous and compound heterozygous variants in IFT81, causing a short-rib thoracic dysplasia, with, or without, polydactyly (SRTD19: OMIM 617895). IFT81 is a protein integral to the core of the intraflagellar transport complex B (IFT-B), which is involved in anterograde transport in the cilium. We describe the case of a male infant with compound heterozygous variants in IFT81, who presented with short long bones, a narrow thorax, polydactyly, and multiple malformations. Three novel clinical features are reported including complete situs inversus, micropenis, and rectal atresia, which have not previously been associated with variants in IFT81. We reviewed the literature and identified the most consistent clinical features associated with this rare ciliopathy syndrome. We postulate that dolichocephaly and sagittal craniosynostosis may be associated with this condition, and provide a clue to considering IFT81 as the causative gene when deciphering complex ciliopathies.