Linkage of preaxial polydactyly type 2 to 7q36

Abstract

We have characterized a 6‐generation North American Caucasian kindred segregating one form of preaxial polydactyly type 2 (PPD‐2). We demonstrate linkage to the 7q36 region and describe a submicroscopic telomeric chromosomal deletion in phase with the PPD‐2 phenotype. Recently, several kindreds segregating triphalangeal thumb (TPT) with and without associated hand anomalies (syndactyly and/or postaxial polydactyly) have also been linked to the subtelomeric region of chromosome 7q [Heutink et al., 1994: Nat Genet 6:287–291; Tsukurov et al., 1994: Nat Genet 6:282–286]. We demonstrate by haplotype analysis that our North American pedigree represents a PPD allele that is independent of the founder PPD allele present in the previously described kindreds.