Duchenne muscular dystrophy

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A disease named after G. A. B. Duchenne, who in 1868 published the first histological account of the pathological changes occurring in the muscles of patients. DMD, the most common type in humans, is X-linked, and it affects about 1 in 3,500 boys. The normal gene, DMD, is composed of about 2,300 kilobases. It is the largest known gene and contains 79 exons. Over 99% of the gene is made up of introns. It takes RNA polymerase II 16 hours to traverse this giant gene. The processed mRNA is about 14 kilobases, and it specifies a protein named dystrophin (q.v.). Victims of Duchenne muscular dystrophy have null mutations in their dystrophin genes. Less severe mutations allow reduced amounts of dystrophin to be produced, resulting in a milder disease called Becker muscular dystrophy (q.v.). There is a mutational hot spot between exons 44 and 45. Orthologs of DMD occur in both dogs and cats. See Chronology, Hoffman, Brown, and Kunkel; Canis familiaris, calveolins, contiguous gene syndrome, hot spot, null allele, RNA polymerase. http://www.mdausa.org.80.

Subjects: Genetics and Genomics.

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