5.6- Gene Therapy

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  • Created by: Rebecca
  • Created on: 21-06-11 20:29

Gene Therapy:

  • The aim of gene therapy is to treat a genetic disease by replacing defective genes in the patient's body with copies of a new DNA sequence.
  • Scientists are now able to identify many more specific genes responsible for genetic disease.
  • The main problem lies in delivering the gene to the correct cells and ensuring they function correctly once they get there.
  • The majority of procedures require viruses to deliver the genes to specific cells. Some use liposomes and others use injections of naked plasma DNA.
  • There are two possible ways of replacing defective genes: 
  • Gene therapy involving somatic cell therapy targets cels in the affected tissues. This method may be therapeutic but the genetic changes are not inherited. The use of stem cells is longer lasting in patients.
  • The other is Germ-line therapy. This involves the introduction of corrective genes into germ-line cells, that is, the gene is replaced in the egg and will enable genetic corrections to be inherited.

Cystic Fibrosis:

  • This is due to a defective autosomal recessive allele.
  • Sufferers produce a thick sticky mucus from the epithelial cells lining certain passageways in the body. These secretions lead to problems such as: block pancreatic duct preventing enzymes from reaching duodenum, leaving food digestion impossible, and clogged bronchioles and alveoli causing congestion and difficulty breathing. Chest infections are common.
  • Chest massages are needed daily, and children may have large appetites to compensate for poor digestion. 
  • To inherit the disease both parents must carry the recessive allele. 
  • Carriers can be identified using a simple blood test. 
  • Normal genes carry the code for a protein called Cystic Fibrosis Transmembrane Regulator (CFTR) which transports chloride ions out of the cells into mucus. Sodium ions follow out and water follows that by osmosis, keeping the mucus at a

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