Darier disease (DD) is an autosomal-dominant skin disorder characterized by loss of adhesion between epidermal cells (acantholysis) and abnormal keratinization. Recently we constructed a 2.4-Mb, P1-derived artificial chromosome contig spanning the DD candidate region on chromosome 12q23-24.1. After screening several genes that mapped to this region, we identified mutations in the ATP2A2 gene, which encodes the sarco/endoplasmic reticulum Ca2(+)-ATPase type 2 isoform (SERCA2) and is highly expressed in keratinocytes. Thirteen mutations were identified, including frameshift deletions, in-frame deletions or insertions, splice-site mutations and non-conservative missense mutations in functional domains. Our results demonstrate that mutations in ATP2A2 cause DD and disclose a role for this pump in a Ca(2+)-signalling pathway regulating cell-to-cell adhesion and differentiation of the epidermis.

Darier's disease (DD) is an autosomal dominantly inherited skin disorder characterized by loss of adhesion between epidermal cells (acantholysis) and abnormal keratinization. Recently, we identified ATP2A2 encoding the sarco/endoplasmic reticulum Ca(2+)ATPase isoform 2 as the defective gene in DD. Now we report a spectrum of ATP2A2 mutations in 19 families and six sporadic cases with DD and investigate genotype-phenotype correlations. All 21 exons and flanking intron boundaries were amplified and screened for mutations by conformation-sensitive gel electrophoresis and direct sequencing. We identified 24 novel mutations that are scattered throughout the ATP2A2 gene. Two families shared an identical mutation on a common disease-associated haplotype, suggesting inheritance from a common ancestor. The majority of the mutations (54%; 13/24) led to a premature termination codon which further supports the proposal that haploin-sufficiency is a common molecular mechanism for DD. Thirty-eight per cent of mutations (9/24) result in non-conservative amino acid substitutions at highly conserved positions. Two mutations predict mutated polypeptides lacking or carrying additional amino acids. Marked inter- and intrafamilial phenotypic variability of the disease was observed. These results illustrate the considerable diversity of ATP2A2 mutations causing DD and suggest that additional factors are important contributors to the clinical phenotype.

Darier disease (DD) (MIM 124200) is an autosomal dominant skin disorder characterized by loss of adhesion between epidermal cells and by abnormal keratinization. We present linkage analysis showing, in four families, key recombination events that refine the location of the DD locus on chromosome 12q23-24.1 to a region of <1 cM. We have constructed a YAC/P1 artificial chromosome (PAC)/bacterial artificial chromosome (BAC)-based physical map that encompasses this refined DD region. The map consists of 35 YAC, 69 PAC, 16 BAC, and 2 cosmid clones that were ordered by mapping 54 anonymous sequence-tagged sites. The critical region is estimated to be 2.4 Mb in size, with an average marker resolution of 37.5 kb. The refinement of the critical interval excludes the ALDH2, RPL6, PTPN11, and OAS genes, as well as seven expressed sequence tags (ESTs) previously mapped in the DD region. The three known genes (ATP2A2, PPP1CC, and SCA2) and the 10 ESTs mapped within the critical region are not obvious candidates for the DD gene. Therefore, this detailed integrated physical, genetic, and partial transcript map provides an important resource for the isolation of the DD gene and, possibly, other disease genes.

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