Refinement of the locus for hereditary congenital facial palsy on chromosome 3q21 in two unrelated families and screening of positional candidate genes

Hereditary congenital facial palsy (HCFP) is an autosomal-dominant disorder consisting of paresis or paralysis of the VIIth (facial) cranial nerve. Genetic heterogeneity for this disorder has been suggested based on linkage analysis in two large Dutch families. Two loci have been identified, one on chromosome 3q21.2-q22.1 (HCFP1) and another on chromosome 10q21.3-q22.1 (HCFP2). Here, we report linkage analysis in a large Pakistani family with dominant congenital facial palsy. A region cosegregating with the disorder was identified on the long arm of chromosome 3, which overlaps with the previously identified HCFP1 locus on chromosome 3q21-q22, thus confirming the involvement of this locus in HCFP. The critical region could be reduced from 5.7 to 3.0cM between the markers D3S3607 and GDB ID:11524500. In addition, mutation analysis on seven candidate genes: KLF15, FLJ40083, PODXL2, TMCC1, PLEXIN-A1, PLEXIN-D1, and GATA-2, was performed. All genes are located within the critical interval of the Dutch HCFP1 family. The genes PODXL2, PLEXIN-D1, GATA-2, and TMCC1 are also located within the smaller critical interval of the Pakistani HCFP family. Based on the results obtained, all seven genes could be excluded as causative genes in HCFP.