Human Diseases Flashcards
Huntington’s Disease
Gain of function mutation
CAG repeats (codes for glutamine- Q)
Normally repeated <35 times, >42 repeats resulted in expanded polyQ tract, causing protein to misfold, forming toxic aggregates killing neuronal cells
Diagnose by PCR to determine size of region containing CAG repeats
Cystic Fibrosis
Loss of function mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene
Codes for an ion channel that regulates water balance in epithelial cells
DF508 is the most comon mutation (Phe 508 missing), causing CFTR protein to misfold within the ER, resulting in its degradation
Diagnosis by southern blot of PCR products with allele specific probes
Human Gene Therapy
Correct a mutant phenotype by adding a normal copy of a gene (transgene) to the genome of the affected individual
Recombinant Retroviruses
Allow stable transgene insertion into the genome
Insertion site is random
ADA-SCID
Adenosine deaminase- deficient severe combined immunodeficiency disease due to accumulation of deoxyadenosine in absence of ADA
Deoxyadenosine is toxic to immature lymphocytes- causes premature death adn immune deficiency
X-Linked SCID
Mutation in the IL2R gc gene results in death of T cells due to lake of interleukin 2
WT gene inserted into the retroviral vector, used to infect patient derived bone marrow stem cells
Grown in culture and implanted back into patient
mhtt Protein
Protein can’t fold properly
Forms neurotoxic aggregates
Gene-addition therapy
Supplies normal gene to cells with the defective gene
Can’t be used with dominant diseases
Gene replacement therapy
Uses homologous recombination to replace the defective gene with a function copy
Targeted gene transfers
Supplies normal gene to precise chromosomal location
Transfer efficiency is very low
Gene editing
Precise targeting of transgene using CRISPR
