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Werner syndrome is a very rare, autosomal recessive disorder; its most recognizable characteristic is premature aging. Werner's syndrome more closely resembles "accelerated aging" than any other "segmental progeria." For this reason, Werner syndrome is often referred to as a progeroid syndrome, as it partly mimics the symptoms of Progeria. The defect is on a gene that codes DNA helicase and it is located on the short arm of the 8th chromosome. As a result DNA replication is impaired. This condition is inherited in an autosomal recessive pattern.
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Individuals with this syndrome typically develop normally until they reach puberty. Following puberty they age rapidly, so that by age 40 they often appear several decades older. The age of onset of Werner syndrome is variable, but an early sign is the lack of a teenage growth spurt, which results in short stature. Other signs and symptoms appear when affected individuals are in their twenties or thirties and include loss and graying of hair, hoarseness of the voice, thickening of the skin, and cloudy lenses (cataracts) in both eyes. Overall, people affected by Werner syndrome have thin arms and legs and a thick torso. Affected individuals typically have a characteristic facial appearance described as "bird-like" by the time they reach their thirties. Patients with Werner syndrome also exhibit genomic instability, hypogonadism, and various age-associated disorders; these include cancer, heart disease, atherosclerosis, diabetes mellitus, and cataracts. However, not all characteristics of old-age are present in Werner patients; for instance, senility is not seen in individuals with Werner syndrome. People affected by Werner syndrome usually do not live past their late forties or early fifties, often dying from the results of cancer or heart disease.
This mutation was first suggested to be autosomal recessive based on studies done between 1920 and 1960, however studies done in the 1970’s show the mutation is autosomal dominant. This finding means that the mutation occurs on only one of the two chromosomes in the pair, rather than on both chromosomes like a recessive mutation would suggest. It has been suggested that the gene for Werner’s Syndrome lies on Chromosome 8, but further evidence is needed to verify this.
There is usually no family history of progeria or Werner’s syndrome in families of affected individuals. Since neither parent carries or expresses the gene, each case is seen as a random, isolated mutation. It is unlikely to have more than one child in a given family affected with progeria because of the rarity of the disease. However it is possible to have identical twins that are both affected with the disease. But because each case is a new sporadic mutation, it is also possible to have one twin with progeria and one without the disease.
There are three main theories as to why progeria occurs. They are:
Helicase Theory http://www.rlc.dcccd.edu/MATHSCI/reynolds/progeria/cellular/cellularmechanisms.html
Mutant Gene Theory http://www.rlc.dcccd.edu/MATHSCI/reynolds/progeria/cellular/cellularmechanisms.html
Telomere Theory http://www.rlc.dcccd.edu/MATHSCI/reynolds/progeria/cellular/cellularmechanisms.html
Werner syndrome is named after Otto Werner, a German scientist, who, as a student, described the syndrome as part of his doctoral thesis in 1904.
This article incorporates public domain text from The U.S. National Library of Medicine
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Werner_syndrome". A list of authors is available in Wikipedia.|