Hydrolethalus syndrome (HLS) is an autosomal recessive lethal malformation syndrome, leading to still-birth, or death shortly after birth. The syndrome is characterised by hydrocephaly, with absent upper midline structures of the brain, micrognathia and polydactyly. A variety of other features (including cleft lip or palate, club feet, anomalies of the ears, eyes and nose, a keyhole-shaped defect in the occipital bone, abnormal genitalia, and congenital heart and respiratory organ defects) have also been observed in affected individuals []. Characterisation of the underlying molecular defect is important, as it could both expose new molecular pathway(s) essential for normal human development and provide new insights into foetal malformation syndromes.The critical HLS region has been defined to a 476 kb interval using cases from 30 Finnish HLS families []. Within this region, sequence analysis has revealed a point mutation in a novel gene (termed HYLS1) that results in substitution of a well-conserved Asp by Gly in the Centriolar and ciliogenesis-associated protein HYLS1, which is essential for early development of the human foetus [].HYLS1 is dispensable for centriole assembly and centrosome function in cell division. Instead, HYLS1 plays an essential role in cilia formation that is conserved between C. elegans and vertebrates [].
This entry represents the C-terminal domain of Centriolar and ciliogenesis-associated protein HYLS1. The HYLS1 gene shows alternative splicing and the transcript is found in multiple tissues during foetal development [, ].
