Solar urticaria may occur in all races but studies monitoring 135 African Americans and 110 Caucasians with photodermatoses found that 2.2% of the African Americans had SU and 8% of the Caucasians had the disease showing that Caucasians have a better chance of getting the disease. The age ranges anywhere from 5–70 years old, but the average age is 35 and cases have been reported with children that are still in infancy. Solar urticaria accounts for less than one percent of the many documented urticaria cases. To put that into a better perspective, since its first documented case in Japan in 1916, over one hundred other instances of the disease have been reported. History
Solar urticaria was first identified by P. Merklen in 1904. Just a year later, in 1905, Ward became the first to induce urticaria through exposure to the sun in a controlled environment. The first documented case came in Japan in 1916. The name "solar urticaria" was proposed in 1923. In 1928 urticaria was induced for the first time. This was carried out by phototesting with increasing amounts of radiation of varying wavelengths. In 1942 the disease was passively transferred to normal volunteers using serum from patients with solar urticaria. References


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Malignant hyperthermia (MH) is a type of severe reaction that occurs in response to particular medications used during general anesthesia, among those who are susceptible. Symptoms include muscle rigidity, high fever, and a fast heart rate. Complications can include muscle breakdown and high blood potassium. Most people who are susceptible are generally otherwise unaffected when not exposed.The cause of MH is the use of certain volatile anesthetic agents or succinylcholine in those who are susceptible. Susceptibility can occur due to at least six genetic mutations, with the most common one being of the RYR1 gene. These genetic variations are often inherited from a persons parents in an autosomal dominant manner. The condition may also occur as a new mutation or be associated with a number of inherited muscle diseases, such as central core disease.In susceptible individuals, the medications induce the release of stored calcium ions within muscle cells. The resulting increase in calcium concentrations within the cells cause the muscle fibers to contract. This generates excessive heat and results in metabolic acidosis. Diagnosis is based on symptoms in the appropriate situation. Family members may be tested to see if they are susceptible by muscle biopsy or genetic testing.Treatment is with dantrolene and rapid cooling along with other supportive measures. The avoidance of potential triggers is recommended in susceptible people. The condition affects one in 5,000 to 50,000 cases where people are given anesthetic gases. Males are more often affected than females.