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Huntington’s Disease. By Harry Kaplan and Jesse Lab Pd. 3. Huntington’s disease facts. Huntington’s disease is the degeneration of nerve cells in the brain. Huntington’s can cause uncontrolled movement, loss of brain function, and a flux of emotions.
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Huntington’s Disease By Harry Kaplan and Jesse Lab Pd. 3
Huntington’s disease facts • Huntington’s disease is the degeneration of nerve cells in the brain. • Huntington’s can cause uncontrolled movement, loss of brain function, and a flux of emotions. • Symptoms of the disease would be mood swings, forgetfulness, and wild finger movements. • Fun Fact: Huntington’s may cause people to change their handwriting.
Where is it? • Huntington’s Diease can be found in chromosome 4.
What are the chances? • Huntington’s disease is an autosomal dominant, which means that only ONE mutated gene is needed to make the disease. • As mentioned, chromosome 4 needs to be altered only once to get the disease.
Alleles • An allele is a form of a gene at a specific location on the chromosome • 2 alleles per gene • Alleles are formed from DNA and originate from the genetic material • In a punnett square, the dominant gene is a capital letter, recessive gene lower case • Dominance: The allele that shows its trait despite the other allele present • Recessiveness: an allele only shown when another recessive gene is present but masked by the presence of a dominant gene.
Homozygous dominent chance: 25%Heterozygous dominent chance: 50%Homozygous recessive chance: 25%
Punnet Square info • Phenotype HH= No HuntingtonsHh= No Huntingtonshh= Huntingtons! • Genotype HH= Homozygous dominent • Hh= heterozygous dominent • hh= homozygous recessive
Ratio of Phenotypes Phenotype • 75% That the child will have Huntington’s disease. 25% that the child will not. • 3:1 ratio Genotype • 25% HH 50%Hh 25% hh • 1:2:1
Huntington’s Punnet Square: Complete Phenotype: HH: No Huntington’s Hh: No Huntington’s hh: Huntington’s Genotype: HH: 50% Hh: 50% hh: 0%
Sample pedigree charts X-linked Autosomal Dominant Autosomal Recessive Circle = female Square = male All White= homozygous recessive gene, person is fine, has 2 copies of the “healthy” gene All Green= homozygous dominant, person have disorder and 2 copies of the “bad” gene Half Green/Half White= because this is a dominant disorder (rules of dominance), the person has the disease and only has one copy of the “bad” gene and one copy of the “healthy” gene. Color gene is “bad” on x chromosome White= Person is fine. May possibly carry the recessive “bad gene.” Can have one “health” and one “bad” gene of two “healthy genes.” Black= Person is affected. Has 2 “bad” genes. Color gene is “healthy” on x chromosome Color gene is “healthy” on x chromosome One gene is “bad”, one gene is “healthy” on the x chromosome Female is fine.
