Darier disease (DD; OMIM 124200) is a rare, autosomal dominant hereditary skin disorder characterized by abnormal keratinization and acantholysis. The causes of DD are defects in the ATP2A2 gene, which encodes the sarco/endoplasmic reticulum Ca(2+) ATPase isoform 2 (SERCA2). The aim of this study was to report a novel splice-site mutation and to examine the relative quantity expression of ATP2A2 gene in a Chinese family with DD. Polymerase chain reaction (PCR) was carried out to amplify the exons and flanking intron boundaries of the ATP2A2 gene followed by direct sequencing. A novel splice-site mutation (IVS20-6T>A) was found in the family, which was confirmed by creating a novel HinfI (NEB Inc) recognition site and RT-PCR. Real-time quantitative PCR showed approximately 53 and 52% reduction of ATP2A2 expression of the proband and his father, respectively. The results support the proposition that haploinsufficiency is a common mechanism for the dominant inheritance of DD.