Rabu, 26 Maret 2014

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Kinds of Genetic Diseases - Some Genetic Disease

Kinds of Genetic Diseases
Some genetic diseases have been studied in the previous sub-chapter. The followings are other genetic diseases that are important to be studied.

Huntington Disease

Huntington disease is a genetics disease which is related to the nerve system. in this case, the sufferer gets unconscious continuous movement in his hands, arms, face, eyes and other parts of his body. The muscles of the parts of his body will get weaker, so that he will get difficulty in walking, talking and eating. Moreover, the sufferer also has problem in the development of concentration, memory and emotion. The Huntington disease is hidden because the symptom will appear in the age of 35 to 50 years old.

Huntington disease was first introduced by George Huntington (US) in 1872. This disease is caused by the mutation of certain gene chromosome number 4. In 1993, the scientists had identified that the genes causing Huntington disease carry an order to compose one big protein called huntingtin One abnormal Huntington gene will also produce abnormal huntingtin protein. The presence of abnormal huntingtin protein Ieads to the death of brain cells.

Cystic Fibrosis

 The suffer of cystic fibrosis The thick and adhesive mucus blocks the function of lungs and pancreas
Cystic Fibrosis is a genetic disorder which makes the body secrete the adhesive and thick mucus abnormally. The mucus will block pancreas and lungs and generate problem in respiratory and digestive tract, infection, and finally death.

Cystic fibrosis is caused by the abnormality in recessive gene in chromosome number 7. The chromosome is responsible for the formation of CFTR. The CFIR (cystic fibrosis transmembrane conductance regulator) is the protein that controls chloride ion to flow in and out of lung cell, pancreas, sweat gland, and small intestine.

If there is no CFTR formed the chloride transport from or out of cell is blocked and the thick and adhesive mucus is formed. The mucus will block organs' channel. The blockage of lungs will block the air flow and disturb the mechanism against bacterial infection. The blockage of pancreas make the important digestive enzymes unable to reach small intestine; therefore, the organ cannot digest food. Lack of CFTR also makes sweat gland unable to reabsorb the chloride ions. As a result, a lot of salt will come out of the body altogether with sweat and it causes dehydration to the body.


Albino is a genetic disorder happening in a body where pigmentation is not formed normally. Melanin pigment is the main factor that gives color in normal person. The pigment is not formed to the albino sufferer because of the absence of tyrosine enzyme that functions in melanin formation. As a result, the person suffering from albino has pale skin, white hair, and pink eyes. They tend to avoid light and always wink their eyes because they do not have any protection towards intense light. The albino sufferer has mystagmus feature or uncontrolled movement of the eyes. This is caused by the absence of melanin in certain brain tissues.

A person suffering from albino has recessive homozygous genotype, mm. The genotype of normal person is MM or Mm. Look at the heredity pattern of the marriage between an albino carrier man and an albino carrier woman in the following figure.

Phenylketouria (PKU) or Mental Disorder

PKU is a genetic disease caused by the recessive gene within autosome. The genotype possibilities of a normal person are AA and, Aa, while PKU sufferer has aa genotype. Look at the following figure.

The person with PKU undergoes deficiency of an enzyme which processes phenylalanine of amino acid; as the consequence, phenylalanine is accumulated in blood. If there is no immediate treatment over PKU, it will lead to mental retardation and serious nerve problem. PKU occurs to around one of 10,000 to 12,000 babies born in USA.

In normal condition, phenylalanine is converted into other form of amino acid, that is tyrosine. In PKU case, hydroxylase phenylalanine enzyme which is responsible for the conversion cannot perform its function properly.


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