Chromosome 11

Only available on StudyMode
  • Download(s) : 37
  • Published : October 2, 2007
Open Document
Text Preview
Chromosome 11 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 11 spans about 134 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the total DNA in cells. Identifying genes on each chromosome is an active area of genetic research. Chromosome 11 likely contains between 1,300 and 1,700 genes. Genes on chromosome 11 are among the estimated 25,000 total genes in the human genome. There are many conditions related to genes on chromosome 11 including Charcot-Marie-Tooth Disease, Alexander Disease, Omenn's Syndrome, Spinocerebellar Ataxia, Aniridia, Denys-Drash Syndrome, Sickle cell anemia, Keratitis, Albinism, and Ewing's Sarcoma (King, 2006).

Charcot-Marie-Tooth disease is a hereditary disorder marked by slowly progressive muscle weakness mostly in the feet and legs, but sometimes in the hands and arms. The weakness results from the degeneration of nerves that stimulate muscle. The disorder is named after three physicians who first identified it in 1886: Jean-Martin Charcot, Pierre Marie, and Howard Tooth. The first symptoms of this disease are usually foot deformities like high arch and flexed toes and difficulty in walking. There is also a tendency to sprain ankles and some difficulty in maintaining balance while standing. It is only necessary for one parent to carry the defective gene for the disease to be transmitted. Male and female children are equally affected. Both electromyography, which is a test measuring the electrical activity of muscle cells, and muscle biopsy tests help diagnosis this disease. There is no known cure for Charcot-Marie-Tooth disease. However, foot deformities can be treated with carefully fitted shoes and proper foot care and regular program of exercise can build up muscles (Torchia, 2005). Alexander disease is a rare, genetic disorder of the nervous system. It belongs to a group of genetic disorders called the leukodystrophies that affect growth of the myelin sheath, the fatty covering on nerve fibers in the brain. Alexander disease, which affects mostly males, usually begins at about 6 months of age. Symptoms may include mental and physical retardation, memory loss, enlargement of the brain and head, stiffness of arms and legs, and seizures. Other symptoms include failure to grow and gain weight at the expected rate and delays on the development of certain physical, mental, and behavioral skills. There is no cure for Alexander disease, nor is there a standard course of treatment. Most children with this disease do not survive past the age of 6. In most cases, Alexander Disease appears to occur randomly for unknown reasons with no family history of the disease (Robertson, 1999). Omenn's Syndrome is a rare, inherited disorder of the immune system. It specifically affects three types of cells in our immune system: B lymphocytes and T lymphocytes. Both of these cells plays an important role in fighting infection. Omenn's Syndrome is estimated to occur 1 in 75,000 births. Equal numbers of boys and girls have been diagnosed with Omenn's Syndrome and it appears to be more common in people of North American or European descent. Children with this disease suffer ear infections, failure to thrive, swollen lymph nodes, enlarged liver and spleen, diarrhea, and possibly a skin rash. Infants with this disease are frequently sick and become ill with bacteria and viruses that unaffected babies easily fight off before showing symptoms of an infection. In order for a child to develop this condition, he or she must inherit a copy of the same gene from each parent. Making the diagnosis of Omenn's syndrome requires early recognition of the characteristic signs and symptoms of immune deficiency. Frequent infections, poor growth, and a persistent, generalized rash are warning signs. While there is no known cure for Omenn's syndrome, bone marrow transplantation has been performed to replace the ineffective...
tracking img