a reduction in SERCA2 expression/activity causes clinical symptoms restricted to the epidermis. One hypothesis that some researchers have given is that other cell types express additional “back-up” Ca2+ pumps that can compensate for the reduced function or expression of the SERCA2 protein, while skin cells rely exclusively on the SERCA2 gene for calcium sequestration, meaning only they are affected by its reduction in expression. As mentioned above, some cases of DAR result from somatic mutations to ATP2A2 in epidermal stem cells. These cases are referred to as instances of "linear" Darier's disease. Such individuals display phenotypic mosaicism, where the Darier's phenotype only affects the subset of epidermal tissue arising from the mutated progenitor cell. Somatic mutations are not inherited by the offspring of such individuals. Diagnosis Diagnosis of Darier disease is often made by the appearance of the skin, family history, or genetic testing for the mutation in the ATP2A2 gene. However, many individuals affected by this disorder are never diagnosed, due to the mildness of symptoms in most cases. Mild cases present clinically are minor rashes (without odor) that can become exacerbated by heat, humidity, stress, and sunlight. The symptoms of the disease are thought to be caused by an abnormality in the desmosome-keratin filament complex leading to a breakdown in cell adhesion. Darier's disease is an incommunicable disorder that is seen in males and females equally. Symptoms typically arise between the ages of 15 and 30. One study of 100 British individuals diagnosed with Darier's disease reported that affected individuals display elevated frequencies of neuropsychiatric conditions. There were high lifetime rates for mood disorders (50%), including depression (30%), bipolar disorder (4%), suicidal thoughts (31%), and suicide attempts (13%), suggesting a possible common genetic link. Several case studies have suggested affected populations display elevated frequencies of learning disorders, but this has yet to be confirmed. Treatment Treatment of Darier disease depends on the severity of the presented clinical symptoms. In most minor cases, the disorder can be managed using sunscreen, moisturizing lotions, avoidance of non-breathable clothing, and excessive perspiration. In more severe cases of Darier's disease, hospitalisation may be required to heal affected individuals who display frequent relapse and remit patterns. In less severe cases, signs and symptoms may clear up completely through hygienic interventions. Most patients with Darier's disease live normal, healthy lives. Rapid resolution of rash symptoms can be complicated due to the increased vulnerability of affected