Syndrome, Cockayne

A genetic disorder characterized by dwarfism, prematurely aging, visual problems and deafness, sensitivity to sunlight, and mental retardation. The disease is due to a defect in the process of repairing RNA. Copying mistakes are frequent. In Cockayne syndrome, one of the enzymes that normally corrects copying errors in dividing cells called RNA polymerase II is defective. The children usually have poor growth before and after birth and are mentally retarded. Eye problems include retinal degeneration, optic nerve atrophy, sunken eyes, poor lid closure and drying of the cornea. The ears tend to be malformed with hearing loss. The head is abnormally small (microcephaly). The arms and legs are disproportionately long with large hands and feet and flexion contractures of joints. The children burn after even minimal sun exposure. They suffer steady deterioration of their neurons. Their abilities to hear, to see, even to feel or smell are progressively lost. Death is often from early atherosclerosis. The disease is inherited as an autosomal recessive trait. The gene, called CSA, is on chromosome 5. Parents with one CSA gene are normal. Each of their children stands a 1 in 4 (25%) risk of receiving two CSA genes, one from each parent, and of having Cockayne syndrome. There are several types of Cockayne syndrome. In Type I, the classic form of Cockayne syndrome, the boys and girls usually die in their teens. In Type II, which rarer and more severe, death usually occurs by age 6 or 7. The syndrome is named for Edward Alfred Cockayne (1880-1956), a London physician who concentrated on diseases of children, particularly hereditary diseases. His 'Inherited Abnormalities of the Skin and its Appendages,' published in 1933, was an extensive collation of family pedigrees from the literature. Cockayne reported the syndrome in 1946.