Exercise 1 (6 points) Huntington Disease Huntington disease is a rare neurodegenerative disease of the central nervous system. It is characterized by uncoordinated and involuntary movements of great amplitude and by psychological problems. It is due to a mutation at the level of the gene coding for a protein called huntingtin which is essential for the survival of the neurons. 1- Pick out from the text 1.1- the origin of Huntington disease. 1.2-the symptoms of this disease. A study is performed on individuals the mutated allele carrying responsible for this disease. Document 2 represents the variation of the percentage of individuals showing the symptoms of the disease as a function of their age. 2- Interpret the obtained results. Document 3 shows the genealogical tree of a family which certain members are affected by the disease. Age (years) Percentage of individuals showing the symptoms of the disease (%) 3- Indicate whether the allele of this disease is recessive or dominant. Justify the answer. 4- Determine the localization of the gene responsible for this disease. Document 1 3 7 Document 2 00 10 30 0 30 O 9 Healthy woman Healthy man 5 2 Fetus 40 60 60 90 Sick man 10 Sick woman 70 100
