Genotype-phenotype correlations in Darier disease: A focus on the neuropsychiatric phenotype.

Darier disease (DD) is an autosomal dominant skin disorder caused by mutations in ATP2A2 encoding the sarco/endoplasmic reticulum Ca2+ ATPase Isoform 2 (SERCA2). Evidence of a population-level association between DD and psychiatric disorders suggests that mutations in ATP2A2 may have pleiotropic effects on the brain as well as skin. Evidence of genotype-phenotype relationships between ATP2A2 mutations and neuropsychiatric phenotypes would further support this suggestion. We investigated genotype-phenotype correlations between lifetime neuropsychiatric features and ATP2A2 mutation type (dichotomized into likely gene disrupting [LGD] or protein altering) in 75 unrelated individuals with DD. We also looked for evidence of clustering of mutations within SERCA2 according to neuropsychiatric features. Combining our data with the existing literature, the rate of LGD mutations was found to be significantly higher among DD cases/families with bipolar disorder, schizophrenia, or affective psychosis (p = .011). We also found a significant relationship between mutations located in the S4-M4 region of the protein and the presence of a severe neuropsychiatric phenotype (p = .032). Our findings add support to the hypothesis that Darier-causing mutations in ATP2A2 confer susceptibility to neuropsychiatric dysfunction, in particular severe psychiatric illness. This, together with evidence from research on common polymorphisms confirms ATP2A2 as a gene at which variation influences susceptibility to major psychiatric illness.

Low-dose ultraviolet B rays alter the mRNA expression of the circadian clock genes in cultured human keratinocytes.

Current understanding of mammalian circadian rhythms suggests that they are regulated by light targeting signaling pathways in the hypothalamic suprachiasmatic nuclei. Recently, investigators have identified the existence of extraretinal photoreceptors and a potential role for the skin in this regulatory process has been implied. We demonstrated that mRNA of the circadian clock genes Per1, Clock, and bmal1/mop3 are expressed in normal human cultured keratinocytes. Low-dose ultraviolet B rays initially downregulate all circadian clock genes and then induce altered expression of the genes in keratinocyte cell cultures. Ultraviolet light targeting superficial layers of skin (keratinocytes) may therefore contribute to circadian rhythm modulation.

Novel ATP2A2 mutations in a large sample of individuals with Darier disease.

Darier disease (DD) is a rare autosomal dominantly inherited skin disorder caused by mutations in ATP2A2, which is expressed in both the skin and the brain and encodes for SERCA2. We have screened the coding regions of ATP2A2 in a total of 95 unrelated individuals with DD to identify the pathogenic mutations. We identified 66 potentially pathogenic mutations in ATP2A2 for 74 of the 95 individuals with DD of which 45 (68%) are thought to be novel. Forty-nine (74%) are unique to an individual and 17 (26%) were found in more than one individual or overlap with previously identified variants. The results suggest that mutations in ATP2A2 may not be as family-specific as first thought. The spectrum of mutations identified will inform understanding of the pathogenesis of DD.