Synpolydactyly of the foot in homozygotes

Metatarsal transfer for the treatment of post-axial metatarsal-type foot synpolydactyly: a new technique that allows for comfortable shoe wearing

We analysed the clinical and radiological outcomes of a new surgical technique for the treatment of heterozygote post-axial metatarsal-type foot synpolydactyly with HOX-D13 genetic mutations with a mean follow-up of 30.9 months (24 to 42). A total of 57 feet in 36 patients (mean age 6.8 years (2 to 16)) were treated with this new technique, which transfers the distal part of the duplicated fourth metatarsal to the proximal part of the fifth metatarsal. Clinical and radiological assessments were undertaken pre- and post-operatively and any complications were recorded. Final outcomes were evaluated according to the methods described by Phelps and Grogan. Forefoot width was reduced and the lengths of the all reconstructed toes were maintained after surgery. Union was achieved for all the metatarsal osteotomies without any angular deformities. Outcomes at the final assessment were excellent in 51 feet (89%) and good in six (11%). This newly described surgical technique provides for painless, comfortable shoe-wearing after a single, easy-to-perform operation with good clinical, radiological and functional outcomes.

Association of Hypospadias with Hypoplastic Synpolydactyly and Role of HOXD13 Gene Mutations

OBJECTIVES

To present the association of hypospadias with hypoplastic synpolydactyly and discuss the molecular genetic basis of these conditions.

METHODS

A large synpolydactyly kindred first described in 1995 was reinvestigated. Affected and unaffected subjects were interviewed, and pedigrees of the most recent generations were constructed. The marriages of two affected individuals were identified. The siblings who were homozygous for the deformity were asked to attend our institution and underwent a detailed clinical evaluation. Genetic studies and mutation screening were performed using polymerase chain reaction on genomic DNA extracted from venous blood.

RESULTS

Of the 245 members of the kindred, 125 individuals were affected. Of these 125 individuals, 12 were homozygotes (6 females and 6 males) with a mean age of 12 years. The remaining 113 individuals (57 females and 56 males) were heterozygotes showing milder limb deformities. No sex-related phenotypic difference was found in the extremity findings, but all the males with a homozygote pattern had hypospadias. Three had distal penile, two had mid-shaft, and one had penoscrotal hypospadias. Of the affected 56 heterozygote males, 22 were also noted to have distal hypospadias in various forms. Neither the heterozygote nor the homozygote females had any genital anomalies. The laboratory tests and karyotype profiles of these individuals were normal. Mutation screening of the homozygote subjects revealed a polyalanine duplication band of nine additional alanine residues at the human HOXD13 gene.

CONCLUSIONS

These findings strongly suggest that specific mutations in HOXD13 gene may cause both hypoplastic synpolydactyly and hypospadias.