Genetic Disorders

Genetic disorders are medical conditions that are caused by errors in the replication of genetic code. Genetic diseases may be evident at birth, while others will only be manifested later in life. Some involve inconveniences, while others are life threatening or fatal.

There are many diseases caused by genetic abnormalities. They create deformity, disease or a tendency to develop certain diseases. Genetic disorders include achondroplasia, agammaglobulinemia, albinoism, ankylosis, cellac disease (celiac sprue), Huntington's Chorea, Christmas disease (hemophilia B), cystic fibrosis, Downs syndrome, dwarfism, Ehlers-Danlos syndrome, epilepsy, Friedreich's ataxia, Gaucher's disease, hemolytic disease of the new born, hemophilia, Hirschsprung's disease (megacolon), Klinefeiter's syndrome, myotonia congentia, osteogenesis imperfecta, phenylketonuria, polycystic kidney, sickle cell anemia, Tay-Sachs disease (gangliosidosis), Thalassemia (hemolytic anemia), Turner's syndrome (gonadal dysgenesis) Von Recklinghausen's disease (neurofibromatosis, Wilson's disease, and many others.

Some genetic disorders such as myopia, color blindness or inherited blepharitis (Seborrheic blepharitis) have mild symptoms. Other genetic diseases such as cystic fibrosis (CF) have severe symptoms. In some cases of inherited diseases such as Huntington's Chorea, death is an inevitable result. Prion diseases (spongiform encephalopathies) such as fatal familial insomnia (FFI) are genetic disorders that are also fatal.

Some genetic disorders arise from a single gene. For this to occur, it is necessary for the single-gene disorder to be carried on a dominant gene. The dominant gene can express the disorder from a single gene. In the case of a recessive gene, two copies of the gene are needed for it to be expressed. The abnormality is expressed as the production of too little or too much of a particular protein.

Genetic diseases may be rare disorders or they may be common. They can be the result of a mistake in the genetic coding of a single gene, or they may involve the whole chromosome. The mistakes may be the result of a reproduction in the mitochondria (self-reproducing) part of cells, or the mistake(s) may be due to chemical or radiation exposure. Radiation exposure included both atomic radiation and natural sunlight.

Skin cancer is the most common type of cancer in United States, South Africa, and Australia. Fair-skinned people, who are exposed to strong sunlight, especially in childhood, are likely to develop some form of skin cancer after the age of 65. They ultraviolet radiation (UV) exposure damages the skin and creates mistakes in the [Page 720]genetic reproduction. Artificial sources of UV light such as tanning beds are also sources of skin cancer.

Abnormalities in genes are common. They are more common in recessive genes than in dominant genes. All human beings carry abnormal genes. On average, each person has from six to eight abnormal recessive genes. Normally these genes are inoperative or do not cause a problem. Only if there is an inheritance from both parents of the same abnormal gene is there a problem. It is the presence of two copies of the abnormal gene that creates genetic disorders.

In the human population at large, there is only a small likelihood that a person will have two copies of an abnormal recessive gene. However, in cases of children born to parents who are close relatives is the risk high. In groups of people such as Orthodox Jews in come communities, and Amish and Mennonites who have intermarried for some generations, the risks are much higher. Abnormal genes that create genetic disorders may be inherited. However, they may also be the result of some spontaneous action that caused a mutation in the genetic code of the gene. The spontaneous mutation may be the result of several causes or of no identifiable cause. In cases where the mutation does not affect the reproductive cells the mutation will simply die out with the individual. However, if the mutation is included in the reproductive cells then the mutation will be transmitted to offspring.

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