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Progeria is a rare disease that causes advanced aging among children

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					Progeria
Andrew Crook Human Genetics: Dr. Ostrowski & Professor McNally

Progeria is a rare disease that causes advanced aging among children. It is thought to have originated from a single dominant de novo mutated gene. The typical life span of a Progeria patient is to their mid teens. Presently there are no known cures for this abnormality.

Background: Recent literature states that Progeria is an extremely rare disorder of a single dominant allele 3. Each new case is thought to be a new mutation because neither parent has the phenotype. Rapid aging is observed in affected children. The classic Hutchinson-Gilford Progeria Syndrome was first described in England in 1886 by Dr. Jonathan Hutchinson. Dr. Hastings Gilford also studied the disorder in 1886 and 1904. The word Progeria comes from the Latin words pro and geraios, which translates into “ early old age”. It affects about 1 in 8 million newborns worldwide with no exception to race or sex. To date there have been about 100 reported cases around the world. The average life span of Progeria patients is between twelve and fifteen years of age, but there are exceptions as some have lived longer. A Progeria body ages about 10 times faster than normal 5. The first symptoms are seen within the first or second year. In their early

teen years they experience the problems that a normal seventy or eighty year old would face. The cause of death is associated with the heart or stroke due to progressive atherosclerosis. Today there is no known cure for the disease. The diagnosis is made during the first or second year with symptoms that include skin changes and failure to gain weight. It is also found that Progeria patients may have the chemical hyaluronic acid found in elevated amounts in their urine. All Progeria patients have similar phenotypes; there is an extremely close resemblance with each of their facies 2 . Treatment for Progeria is limited to low dosage of aspirin as an attempt to delay atherosclerosis. Progeria patients are forced to accept their condition and realize that the prognosis is going to be death at an early age.

Symptoms: The symptoms of Progeria patients consist of a narrow, wizened bird-like facies, baldness, loss of eyebrows and eyelashes, dwarfism due to the lack of growth, and a large head. They have a small jaw, dry, scaly skin, and a limited range of motion. The connective tissue of the skin becomes tough and hardened. A form of diabetes involving resistance to insulin may also develop. There are also many other symptoms that are associated with old age, such as arthritis, and permanent tooth loss 4. Even though their physical development deteriorates, mental development and intelligence is entirely normal. Death is usually due to heart attack or stroke between the twelfth and fifteenth year 5.

Figure 1 Phenotype of Progeria patient.

Conclusion: Today scientists are still perplexed by this abnormality even though it has been seen for more than a hundred years. Any advancements in the near future as to a cure or information about what causes Progeria would be highly unlikely because of its rarity.

Queries of the Literature: 1. What is the cause of Progeria? The cause of the abnormality may be due to a defect in the DNA repair mechanism. It is not known if multiple genes are involved with the disease. Since there have been only 100 reported cases 2 it is impossible to identify the exact location of the mutated gene because of lack of affected families that can be studied. It is highly unlikely that the exact cause of Progeria will be found in the near future 5 .

2.

How does the aging process occur? There are many theories as to why our body ages the way it does and eventually terminates. In our body, DNA is constantly

being repaired. Errors occur routinely, but most of them are caught before they do any damage. This DNA repair mechanism routinely repairs mistakes made in our DNA sequences. The enzyme DNA polymerase is the catalyst responsible for this process. When the mechanism doesn’t work, mutations occur which lead to damaged cells 3. One theory as to why we age is that this mechanism becomes less efficient in our cells as we get older. The accumulation of errors in the genetic material causes cellular death because they cannot function properly. This could be why our body deteriorates as it ages. Another theory is the Hayflick limit which describes how our cells have a predisposed number of cell divisions 1. Also, research has focused on DNA at the ends of chromosomes called telomeres (Figure 2). The telomeres consist of a simple sequence of genetic code that is repeated. As we get older sections of the telomeres are lost. Cellular death occurs when the chromosomes do not have any telomeres left. The removal of certain amounts of the telomeres could also be responsible for the aging process 1. The telomeres located on the chromosomes of Progeria patients are not up to the standard of normal children their age.
Figure 2

Telomeres a re located at each end of the chromosomes.

References: 1. Best, Ben “Mechanisms of Aging” www.benbest.com/lifext/aging.html Brown, Ted 2. Brown, Ted “The Progeria Syndrome Fact Sheet” http://progeria.net/top_what.htm 3. Britnnica “DNA repair”
http://www.britannica.com/bcom/eb/article/4/0,5716,120935+12+111157,00.html

4. Web MD “Progeria” http://my.webmd.com/content/asset/adam_disease_progeria 5. HealthLinkUSA “Progeria”
http://www.healthlinkusa.com/411_getpage.asp?http://privat.schlund.de/p/progeria/ progria_uk.html

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