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Disease That Result from Expansion of Trinucleotide Repeats

Disease That Result from Expansion of Trinucleotide Repeats. Tianyang Wang. Genes transmit from generation to generation Rarely changes. Is it virtually this case?. Gene changes dramatictly. Dynamic mutation, 1991. Affect genes containing a repeating trinucleotide. Small number, stable.

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Disease That Result from Expansion of Trinucleotide Repeats

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  1. Disease That Result from Expansion of Trinucleotide Repeats Tianyang Wang

  2. Genes transmit from generation to generation • Rarely changes Is it virtually this case?

  3. Gene changes dramatictly Dynamic mutation, 1991 Affect genes containing a repeating trinucleotide Small number, stable Large number, unstable Critical number——onset disorders

  4. Diseases attributed to expansion of trinucleotide repeat • Huntington’s disease • Fragile X syndrom • Myotonic dystrophy

  5. Dominant • Spinocerebellar Ataxia (SCA) 1,2,3….. • Recessive • Friedreich Ataxia • Ataxia With Vitamin E Deficiency (AVED) • Ataxia Telangiectasia • Ataxia With Retained Reflexes • Genetic Ataxia

  6. SCA Atrophied cerebellum

  7. Fragile X syndrome

  8. Categories of Disease • Type Ⅰ • CAG repeats within coding portion or exon • Neurodegenerative disorders • Type Ⅱ • Variety of trinucleotide repeats within noncoding portion

  9. Categories of Disease

  10. Huntington’s Disease (HD) • Type Ⅰ disease • Affects about 1:10,000

  11. Huntington’s Disease (HD) • Involuntary, uncoordinated movements • Change in personality • Gradual intellectual decline • Symptoms

  12. ventriculi lateralis

  13. Expanded ventriculi lateralis and atrophied caput nuclei caudati

  14. Huntington’s Disease (HD) • Dominant genetic disorder Not losing a function, but acquiring an additional function Gain-of-function mutation

  15. Huntington’s Disease (HD) • Gene Identified In 1993 Autosomal 4 CAG Repeat Polyglutamine tract (huntingtin) Normal huntingtin —— 6~35 repeats Abnormal huntingtin —— more than 35 repeats

  16. Huntington’s Disease (HD) Why dose only huntingtin containing more than 35 glutamine residues cause the HD?

  17. Huntington’s Disease (HD) • Abnormal folding • Binds to other mutant huntingtin • Binds other protein Transcription factors, such as TBP & CBP

  18. Never fiber tangle of Alzheimer’s victim

  19. Huntington’s Disease (HD) • Genetic anticipation Disease passed from generation to generation, its severity increases and/or it strikes at an increasingly early age.

  20. Huntington’s Disease (HD) There is no efficient drug that can cure the HD by now. But people are trying their best to defeat it!!!

  21. World Congress on Huntington's Disease: 11th–13th September 2005 International Huntington Association Meeting: 13th–14th September 2005

  22. Reference • Dr David Amor, Novel Mechanisms of genetic disease, Murdoch Children Research Institute • 楊永正,基因體計畫(續),陽明生物資訊所, Jan. 3, 2005 • www.hda.org.uk ,The Huntington’s Disease Association

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