Huntington's Disease
Storyboard Text
- Huntington's Disease is one of the most seen dominantly inherited genetic disorders.
- HD patients suffer from movement disorder, psychiatric symptoms, and cognitive impairment.
- affected (blue) father
- unaffected (gray)mother
- The age of the HD onset can vary, but the progression of the disease is certain to occur, and the patient often dies 15 to 20 years after the onset of HD.
- Family members who inherit this faulty gene show no symptoms until mid or late life; thus, there is a deterioration of the brain leading to a progressive loss of motor control and cognitive decline.
- The cause of the disorder at the anatomical level is a loss of neurons, particularly in the corpus striatum and regions of the cerebral cortex.
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- Genetic linkage analysis in large Huntington's disease pedigrees was used to localize the disease locus to the tip of chromosome 4, with further genetic and physical mapping leading to the identification of a novel gene and corresponding protein, ‘huntingtin’ or ‘IT15’.
- Lack of homology to other known proteins or functional protein domains has left Huntington's disease researchers at a loss to the gene's normal function.
- Its expression pattern does not provide any insight into the neuronal specificity of disease pathogenesis.
- The normal huntingtin gene contains a CAG tri-nucleotide repeats in the beginning of the protein-coding sequence, but HD is caused by one copy of the gene containing an abnormally large expansion of this repeat.
- The huntingtin-expressing cells contain more glutamines which in the huntingtin protein is suggestive of a change of function -they are important in the function of DNA-binding proteins involved in the regulation of transcription - which would explain the observed dominant inheritance pattern.
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