Progeria
A young man with Progeria. This is the lighter
side of the disease.
Genetic Cause and Pattern of Inheritance
Evidence suggests that the gene for progeria may be found on chromosome 1. It is believed to be passed on in an autosomal dominant fashion through a mutation. The disorder is transmitted to children by autosomal dominant inheritance. Autosomal means that the mutation occurs on a chromosome that does not determine gender, which in this case is the first chromosome. This means that either parent, if they are affected, has a 50% chance of passing it to any child they have, regardless of gender. Even if a person has one dominant copy of the gene, they are affected. An affcted person is either heterozygous (one dominant copy and one recessive copy) or homozygous dominant (two dominant copies); someone who is not affected is homozygous recessive (two recessive copies). This new mutation is believed to happen at conception sporadically and permanently. New mutations occur as a result of both genetic and environmental factors. New mutations can be either chromosomal abnormalities or point mutations. Research is ongoing to indentify a more specific genetic mutation that causes progeria syndrome. The condition results from new mutations in the LMNA gene, and almost always occurs in people with no history of the disorder in their family. The LMNA gene provides instructions for making several slightly different proteins called lamins. The two major proteins produced from this gene, lamin A and lamin C, are made in most of the body's cells. These proteins have a nearly identical sequence of protein building blocks (amino acids). The small difference in the sequence makes lamin A longer than lamin C. Although progeria is most often found in newborns and children of young ages (in which case it may be called Hutchinson-Guilford Progeria Syndrome or Guilford Syndrome or HGPS for short), adults can begin to show signs of progeria as well (in which case it is called Werner's Syndrome).
-LMNA-- lamin A/C
Symptoms
General symptoms are that patients are short and weigh less than they should according to their height. The infected usually dont grow beyond 3.7 feet tall and weigh only about 40 pounds. The patients skin is usually thin, dry, and wrinkled, exhibiting the signs of aging. The skin in the hands and feet is pushed inwards. Their skin shows changes which are usually in the form yellow-brownish spots. The nails are usually thin, small and underdeveloped. Many patients experience hair loss or alopecia of the scalp, eyelashes, and eyebrows. Their bones are underdeveloped and they can also have soft spots on their skull just like a newborn baby. They may also have bone deterioration of the colorbone, hips and the finger tips. Hip joints in these patients are affected because of alteration in the bone structure of the femur. This cause the femur to sit in more of a straight-line relationship to the hip joint therefore causing an abnormal wide-based walking appearing as if in a horse-riding stance.The patients eyes often appear prominent. This is in part secondary to the changes in bone structure in the face. Other examples would be that the head is too big for the face and there are prominant veins on the scalp, prominant eyes, delayed and abnormal tooth formation, loss of body fat and muscle, and stiff joints. These children usually die from Heart Disease at around age 13.
Treatment / Cure
There is no cure for progeria. Treatment is symptomatic and aimed at providing psychological support rather than medicine. Relieving measures such as wearing a wig may be beneficial for the patient. Relief from chest pain due to changes in arteries can be accomplished by nitroglycerin. Nitroglycerin is a medication that relaxes muscle fibers in blood vessels causing them to expand or dilate. This permits proper blood flow to affected areas, which enables cells and tissues to receive adequate amounts of the oxygen necessary for cell maintenance.
Sources:
<http://galenet.galegroup.com/servlet/SciRC?locID=mart90629&bi=SU&bt=progeria&c=2&t=1&ste=21&docNum=CV2642500334&st=b&tc=31&tf=8>
<http://www.galenet.com/servlet/SciRC?locID=mart90629&bi=SU&bt=Progeria&c=2&t=1&ste=21&docNum=CV2642500334&st=b&tc=31&tf=8>
Link to Human Genetic Disease Project Page
Link to TorresBioClan Home Page
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