Background Mutations in TRPV4, a gene that encodes a Ca 2+ permeable non-selective cation channel, have recently been found in a spectrum of skeletal dysplasias that includes brachyolmia, spondylometaphyseal dysplasia, Kozlowski type (SMDK) and metatropic dysplasia (MD). Only a total of seven missense mutations were detected, however. The full spectrum of TRPV4 mutations and their phenotypes remained unclear. Objectives and methods To examine TRPV4 mutation spectrum and phenotypeÀgenotype association, we searched for TRPV4 mutations by PCR-direct sequencing from genomic DNA in 22 MD and 20 SMDK probands. Results TRPV4 mutations were found in all but one MD subject. In total, 19 different heterozygous mutations were identified in 41 subjects; two were recurrent and 17 were novel. In MD, a recurrent P799L mutation was identified in nine subjects, as well as 10 novel mutations including F471del, the first deletion mutation of TRPV4. In SMDK, a recurrent R594H mutation was identified in 12 subjects and seven novel mutations. An association between the position of mutations and the disease phenotype was also observed. Thus, P799 in exon 15 is a hot codon for MD mutations, as four different amino acid substitutions have been observed at this codon; while R594 in exon 11 is a hotspot for SMDK mutations. Conclusion The TRPV4 mutation spectrum in MD and SMDK, which showed genotypeÀphenotype correlation and potential functional significance of mutations that are non-randomly distributed over the gene, was presented in this study. The results would help diagnostic laboratories establish efficient screening strategies for genetic diagnosis of the TRPV4 dysplasia family diseases.

Between 1994 and 1997 we used the Ilizarov apparatus to treat 12 recurrent arthrogrypotic club feet in nine patients with a mean age of 5.3 years (3.2 to 7). After a mean of three weeks (two to seven) for correction of the deformity and 1.5 weeks (one to four) for stabilisation in the apparatus, immobilisation in a cast was carried out for a mean of 14 weeks (7 to 24). The mean follow-up period was 35 months (27 to 57). Before operation there were one grade-II (moderate), eight grade-III (severe) and three grade-IV (very severe) club feet, according to the rating system of Dimeglio et al. After operation, all the club feet except one were grade I (benign) with a painless, plantigrade platform. Radiological assessment and functional evaluation confirmed significant improvement. Two complications occurred in one patient, namely, epiphysiolysis of the distal tibia and recurrence of the foot deformity. These results suggest that our proposed modification of the Ilizarov technique is effective in the management of recurrent arthrogrypotic club foot in young children.