Second family provides further evidence for causation of Steel syndrome by biallelic mutations in COL27A1.

Steel syndrome is a rare disorder of the skeleton characterized by facial dysmorphism, short stature, carpal coalition, dislocated radial heads, bilateral hip dislocation and vertical talus. Homozygous variants in COL27A1 were reported in an extending family from Puerto Rico. Here, we report a 5-year-old girl from a non-consanguineous family with facial dysmorphism, short stature, carpal coalition, dislocation of radial heads, bilateral hip dislocation, scoliosis and vertical talus. Exome sequencing identified 2 novel compound heterozygous variants c.521_528del (p.(Cys174Serfs*34)) and c.2119C>T (p.(Arg707*)) in COL27A1 in this child and the parents were heterozygous carriers. We hence report the second molecularly proven case of Steel syndrome and the first case to be reported among non-Puerto Rican population. Our report further validates the role of COL27A1 mutations in causation of Steel syndrome.