Gene Therapy Flashcards
What is the cause of Down’s syndrome ?
Karyotype has an extra chromosome 21 ( 3 instead of 2)
Characteristics; wide round face, lower cognitive ability, enlarged tongue, equal length fingers, webbed neck
How are chromosomal diseases caused?
Gametes have abnormal chromosome numbers and mutations
Offspring inherit extra chromosome or are missing one
Caused by problems with meiosis ( non disjunction of chromosome- not pulled apart properly)
How is inheritance controlled?
By effects of 2 alleles
Some are dominant eg. Widows peak ( WW or Ww)
Recessive eg. Straight hair line (ww)
Others can be co dominant
What is huntingtons disease?
Results in a loss of muscle control and mental function
Symptoms don’t appear until after 30 yrs
Affects 1:10000
Caused by dominant allele
What is cystic fibrosis?
Thick mucus in bronchi interferes with lung function
1:25 are carriers
First genetic disease studied for gene therapy
Most lethal autosomal recessive disorder in USA
What is sickle cell anaemia?
Co dominant disorder found in African Americans (recessive allele)
RBC sickle shaped cause problems with anaemia and circulation(pain)
Affects 1:400
Can be fatal- possible cure bone marrow transplant
Sickle cell trait can prevent malaria
What is haemophilia?
A disorder where persons blood doesn’t clot properly
It’s recessive sex linked - X chromosome disorder.
1:10000 males are affected
Royalty disease
What is Adenoside Deaminase (ADA) deficiency or SCIDS ( severe immunodeficiency )?
Affected by severe immunodeficiency - recurrent infections that maybe life threatening
First disease approved for gene therapy
Autosomal recessive
Drug exists but need life long injection - expensive
What is gene therapy?
Treatment or cure for disorders caused by mutated genes
Involves adding normal functioning copy of gene to enough affected cells to restore normal function
What is germ line and somatic gene therapy?
Germ- permanent transfer of gene into egg or sperm ( passed on to future generations)
Somatic - only the transfer of genes to affected cells
What diseases have been successful in treating with gene therapy?
Melanoma
SCIDS
Hereditary blindness
Sickle cell anaemia
How is gene therapy done?
Vector inserts healthy gene into mutated cell - new gene in cell along with original genes. Researcher must:
Identify problem gene, make copies of normal gene, insert copies into vectors, activate the gene so that transcription and translation occur.
What vectors can be used in gene therapy?
Bacteria - plasmids
Viral vectors- advantage infect many cells, integrate into host genome so can’t be lost. Disadvantages- toxicity, immune response, difficult to work with, can produce dangerous recombinations eg. Cancer and some don’t integrate into host genome so are lost
Research to try and produce better vectors without these problems
