A new locus for postaxial polydactyly type A/B on chromosome 7q21-q34.
Postaxial polydactyly (PAP) is the occurrence of one or more extra ulnar or fibular digits or parts of it. In PAP-A, the extra digit is fully developed and articulates with the fifth or an additional metacarpal/metatarsal, while it is rudimentary in PAP-B. Isolated PAP usually segregates as an autosomal dominant trait, with variable expression. Three loci are known for PAP in humans. PAPA1 (including PAP-A/B in one patient) on 7p13 caused by mutations in the GLI3 gene, PAPA2 on 13q21-q32 in a Turkish kindred with PAP-A only, and a third one (PAPA3) in a Chinese family with PAP-A/B on 19p13.1-13.2. We identified a fourth locus in a large Dutch six-generation family with 31 individuals including 11 affecteds. Their phenotype varied from either PAP-A, or PAP-B to PAP-A/B with or without the co-occurence of partial cutaneous syndactyly. We performed a whole-genome search and found linkage between PAP and markers on chromosome 7q. The highest LOD score was 3.34 obtained at D7S1799 and D7S500 with multipoint analysis.
Galjaard
Robert-Jan H
RJ
Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands. r.galijaard@erasmusmc.nl
Smits
Arie P T
AP
Tuerlings
Joep H A M
JH
Bais
Aagje G
AG
Bertoli Avella
Aida M
AM
Breedveld
Guido
G
de Graaff
Esther
E
Oostra
Ben A
BA
Heutink
Peter
P
D002897:Chromosomes, Human, Pair 7; D005260:Female; D008040:Genetic Linkage; D005819:Genetic Markers; D006239:Haplotypes; D006801:Humans; D008297:Male; D010375:Pedigree; D017689:Polydactyly / Q000235:genetics*
D005819:Genetic Markers