Analysis of two candidate genes for Basan syndrome

Basan syndrome is an extremely rare ectodermal dysplasia with autosomal dominant inheritance and variable expressivity. The etiology of Basan syndrome remains unknown. To identify the Basan syndrome gene, we sequenced keratin 14 (KRT14) and SMARCAD1 in a previously unreported kindred with the disease. Sequencing of the coding regions and splice junctions of KRT14 and SMARCAD1 was performed using PCR-amplified genomic DNA isolated from blood or saliva and standard PCR protocols. In vitro functional studies were performed for a variant identified in SMARCAD1. While direct sequencing of KRT14 failed to reveal any likely pathogenic sequence alterations or splice site variants, a heterozygous splicing variant (c.378+3A>T) that segregated with the disease was identified in the skin-specific isoform of SMARCAD1. In vitro studies failed to demonstrate a splicing defect in SMARCAD1. We screened two candidate genes for Basan syndrome in a 3-generation pedigree. The skin-specific isoform of SMARCAD1 remains a good candidate for this disease.