Localization of the syndactyly type II (synpolydactyly) locus to 2q31 region and identification of tight linkage to HOXD8 intragenic marker

Syndactyly type II (SynPolyDactyly; SPD) is an autosomal dominant condition with incomplete penetrance and variable expressivity. Sixty-two meioses from a kindred with 425 individuals were used to map the SPD locus to 2q31 region, approximately 1.7 cM (Lod score = 12.96) centromeric to HOXD8 intragenic marker. Other homeobox-containing genes in this region have previously been ordered as cen-DLX1/DLX2-EVX2-(5' --> HOXD13..HOXD8.HOXD1 --> 3')-tel')-tel. A single recombinant with HOXD8 excluded the most 3' end of HOXD cluster as a candidate site for SPD, but a mutation in the 5' end of HOXD cluster, especially in HOXD13, EVX2 or DLX2/DLX1, may still be responsible for this phenotype. An updated order of D2S142-D2S111-(D2S335/D2S333)-D2S326-D2 S1238-SPD- (HOXD8/D2S1244)-(D2S300/D2S138)-D2S148- D2S324- D2S1384-D2S434 sequence:see text was deduced from meiotic recombination events.