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.
Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands. r.galijaard@erasmusmc.nl
Robert-Jan H
RJ
Galjaard
Arie P T
AP
Smits
Joep H A M
JH
Tuerlings
Aagje G
AG
Bais
Aida M
AM
Bertoli Avella
Guido
G
Breedveld
Esther
E
de Graaff
Ben A
BA
Oostra
Peter
P
Heutink
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