Huntington’s Disease

Um AL-Qura Unversity

D; Yildiz ALKilani

History/ Overview Huntington’s disease was

first found in 1872 when an American doctor that was 22 years old named George Huntington wrote a paper called On Chorea. After his paper was published, the disorder he wrote about was known as Huntington’s Chorea. In the 18th and 19th century it was hard for scientist to understand the chronic adult hereditary of Chorea because the people who had it couldn’t live long enough for the symptoms to develop

Huntington’s Disease

Huntington's disease (HD) is an inherited, degenerative brain disorder which results in an eventual loss of both mental and physical control. The disease is also known as Huntington's chorea. Chorea means "dance-like movements" and refers to the uncontrolled motions often associated with the disease

Who Gets Huntington’s?

• How many and what type of people get this disease?• About 30,000 people have it in the U.S., Canada,

Mexico, and other areas of North America.• This disease can affect anyone, but research shows

that those with European descent have it most.• Huntington’s is also unbiased when it comes to

gender. Males are as equally able to have it as females.

• Symptoms usually begin to appear during one’s middle years…..around the late thirties to early fifties. However, one can be screened at any time.

• Inherited disease (Autosomal Dominant)

• From parent to child• Each child has 50%

chance of inheriting the disease

• If child does not develop disease they cannot pass it on to later generation.

Mode of Inheritance

Location

Located in the Autosomal ChromosomeNot a Sex Chromosome

(Not X-Linked)Localized on the 4th

Autosomal chromosome pair. Chromosome #4

Located in every chromosome

Huntington’s• Looking back at the pedigree

chart is Huntington’s dominant or recessive?

• Scientists have discovered that the abnormal protein produced by the Huntington's disease gene, which contains an elongated stretch of amino acids called glutamines, binds more tightly to HAP-1 than the normal protein does.,

• 11-34 CAG triplet repeats are normal:

• encodes a run of 11-34 glutamine amino acid residues in the protein.

• A run of > 34 glutamine residues causes the protein to aggregate in the brain cells and

• cause progressive cell death

1 ttg ctg tgt gag gca gaa cct gcg ggg gca ggg gcg ggc tgg ttc cct ggc cag cca ttg 61 gca gag tcc gca ggc tag ggc tgt caa tca tgc tgg ccg gcg tgg ccc cgc ctc cgc cgg 121 cgc ggc ccc gcc tcc gcc ggc gca cgt ctg gga cgc aag gcg ccg tgg ggg ctg ccg gga 181 cgg gtc caa gat gga cgg ccg ctc agg ttc tgc ttt tac ctg cgg ccc aga gcc cca ttc 241 att gcc ccg gtg ctg agc ggc gcc gcg agt cgg ccc gag gcc tcc ggg gac tgc cgt gcc 301 ggg cgg gag acc gcc atg gcg acc ctg gaa aag ctg atg aag gcc ttc gag tcc ctc aag 361 tcc ttc cag cag cag cag cag cag cag cag cag cag cag cag cag cag cag cag cag cag 421 cag cag cag caa cag ccg cca ccg ccg ccg ccg ccg ccg ccg cct cct cag ctt cct cag

21 CAG repeats in a “normal”/usual Huntington disease gene

Mode of Inheritance

• Inherited disease (Autosomal Dominant)

• From parent to child• Each child has 50% chance of

inheriting the disease• If child does not develop disease they

cannot pass it on to later generation.

Alleles

• Each person has 2 alleles per gene.• We represent dominant alleles by a

capital letter.• We represent recessive alleles by a

small letter• HH means they have 2 bad genes .• Hh means they have 1 bad gene, and

1 good gene.• hh means they have 2 good genes .

Punnett Squares

• Ratio of the chance of offspring inheriting Huntington’s Disease; ratio determined by parents

• Each punnett square represents the chances PER CHILD

Hh hh

Hh hhh

h

hH

Mother

heterozygous dominant Homozygous

recessiveFather

HH Hh

Hh Hh

homozygous dominant

H

H

h

h

Probability Using Ratios and Percentages

• Ratios:– Must equal 4; 4 possibilities– Ratio is lined up in this format:

Homozygous dominant : heterozygous dominant : homozygous recessiveex: 1 : 2 : 1ex: 1HH : 2Hh : 1hh

• Percentages:– Must equal 100; each possibility equals 25%– Put percentages into the ratioex: 25% : 50% : 25%ex: 25%HH : 50%Hh : 25%hh

HH HhHh hh

H

h

H h

Genotype and Phenotype Probability

• Phenotype:– Ratios:

• 3 HH: 1 no HH– Percentages:

• 75% HH: 25% no HH

• Genotype:– Ratios:

• 1HH : 2Hh : 1hh– Percentages:

• 25%HH : 50%Hh : 25%hh

HH Hh

Hh hh

H

H

h

h

Student Practice

Phenotype:

Ratio:Percentage:

Genotype:

Ratio:

Percentage;

4 HH: 0 no HH

100% HH :0% no HH

2HH : 2Hh

50%HH: 50%Hh HH HH

Hh Hh

H

H

h

H

Pedigree

• Circle: Male

• Square: Female

• All Blue: Homozygous Recessive. No bad gene. Person has no disease

• All Green: Homozygous Dominant. Two bad genes. Person has the disease

• Blue/Green: Heterozygous Dominant. 1 bad gene and 1 good gene. Person carries the bad gene and can pass it one, but is not infected

Pedigree Table for Huntington’s Disease

http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/Autosomal_Dominant_Pedigree_Chart.svg/600px-Autosomal_Dominant_Pedigree_Chart.svg.png

Huntington Disease (HD)

• Physical features: - involuntary

movements- weight loss- abnormal gait- speech & swallowing

difficulties.

• Psychiatric Manifestations:- personality changes - depression- aggression- early onset dementia.

Pictures of People with Huntington’s Disease

Video of Person with Huntington’s Disease

Click the play button in the bottom left hand corner. Not the actual video! After, click on the blue (outside of the video) and press the space bar to continue.

Treatment and Prevention• how to treat Huntington's Disease ؟ • Unfortunately, there is no legitimate cure

for Huntington’s yet, but research should yield one within the next decade or less.

• However, there are clinical trials and medications to help reduce and prolong symptoms, as long as the disease is discovered early.

• Most medicines are meant to help with depression resulting from Huntington’s. Examples include Prozac, Zoloft, Lithium (generic), and about a dozen others.

• Despite all of this, the only way to prevent Huntington’s is in future generations. Couples who have the risk of passing down Huntington’s use genetic screening to detect infected gametes, usually using IVF to have healthy children.

Prozac, Zoloft, Lithium

Chlorpromazine : Ingredients :-chlorpromazine hydrochloride (active ingredient) _   lactose monohydrate_ maize starch_ colloidal silicon dioxide_ magnesium stearate_ polyethylene glycol

Chlorpromazine

Synthesis:The synthesis of chlorpromazine begins with the reaction of 1,4-dichloro-2-nitrobenzene with 2-bromobenzenethiol. Hydrogen chloride is evolved as a by-product of this step and a thioether is formed as the product. Although not verified, it appears that the ortho-chlorine is eliminated preferentially. In the second step the nitrogroup is reduced with hydrogen gas. Upon heating in DMF solvent, ring cyclization occurs. In an analogous manner to what was done in the preparation of promazine, the 2-chloro-10H-phenothiazine of the last step is combined with 3-chloro-N,N-dimethylpropan-1-amine in the presence of sodamide base

Haloperidol Ingredients :Haloperidol decanoateBenzyl alcoholSesame Oil

Haloperidol

Woody Guthrie

In 1973 Woody Guthrie died of Huntin In 1973 Woody Guthrie died of Huntington’s Disease after fifteen years of hospital-zationgton’s Disease after fifteen years of hospital-zation From Woody Guthrie who died because he was heterozygous for the Huntington gene.

• From Arlo Guthrie who inherited two recessive normal genes

• From Nancy Wexler, who identified the location of the gene on chromosoFrom Nancy Wexler, who identified the location of the gene on chromosome Me

• From Bob Dylan who

went to New York to visit Woody in the hospital

The End

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