The 10q24-linked split hand/split foot syndrome (SHFM3): narrowing of the critical region and confirmation of the clinical phenotype.

In this communication we describe the clinical and molecular genetic findings in a family with a variable ectrodactyly linked to SHFM3. This is only the second detailed report of the clinical features of the SHFM3 linked syndrome in a large pedigree. Within this family the expressivity of the condition ranges from the classical ectrodactyly deformity to partial absence of the thumb and agenesis of the distal tip of the index finger. There is discordant limb severity, with the feet more severely affected than the hands. Two individuals have a nail dysplasia indicating the presence of a minor ectodermal component. A cleft palate was present in one individual. Radiological features of family members include short metacarpals with rounded proximal heads, agenesis of the radial ray, epiphysial coning, and an unusual supernumerary ossicle opposed to the distal phalanx of the left thumb. Genetic mapping studies in this family exclude p63 involvement and demonstrate that ectrodactyly in this pedigree is linked to the SHFM3 region on chromosome 10q24. A meiotic recombination event enabled exclusion of a maximum of 1.9 Mb of DNA from the previously known critical region thereby narrowing the critical interval to between D10S1265 and D10S222, with the minimal critical region being between D10S1240 and D10S1267. Further investigations are in progress to identify the gene within the SHFM3 critical region responsible for ectrodactyly.