The deletion does not involve the PTCH1 gene, but instead 30 other gene,s including the ROR2 gene (MIM *602337) which causing both brachydactyly type 1 (MIM #113000) and Robinow syndrome (MIM #268310), and the immunologically active SYK gene (MIM *600085).
We here report a novel nonsense mutation in ROR2 (c.1324C>T; p.R441X) causing intracellular protein truncation in a patient exhibiting features of RRS in conjunction with severe recessive brachydactyly.
In contrast to the human situation, mice heterozygous for Ror2(W749FLAG) are normal and do not develop brachydactyly, whereas homozygous mice exhibit features resembling RRS.
Haploinsufficiency of PTCH causes the BCNS syndrome and mutations in ROR2 have been found in an autosomal recessive Robinow syndrome and a dominantly inherited brachydactyly type 1B.
The same gene, ROR2, has been shown to cause autosomal dominant brachydactyly B, but it is not known at present whether the autosomal dominant form of Robinow syndrome is also caused by mutations in ROR2.