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Human Genetic Diseases

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Presentation on theme: "Human Genetic Diseases"— Presentation transcript:

1 Human Genetic Diseases
(Simple Dominance Inheritance)

2 Dominant Human Diseases
Only have to inherit it from one parent Having disease is dominant to not having disease If child has it, a parent must have it also

3 Huntington’s Disease Inheritance Pattern: Dominant Symptoms:
Breakdown of brain tissue Irritability, forgetfulness, loss of coordination

4 Huntington’s Disease (cont.)
Other Important Information: Rare but lethal Symptoms show up between years old May have already had kids 13 has Huntington’s Disease! Woody Guthrie

5 Example Problem: A man who is homozygous for HD and a woman that does not have HD have a child. What is the chance that the child will have HD?

6 Achondroplasia Dwarfism Inheritance Pattern: Dominant Symptoms:
Short arms and legs Normal skull and torso

7 Achondroplasia (cont.)
Other Important Information: Inhibits bone growth (cartilage slow to turn to bone) Most have normal life expectancy

8 Example Problem: What is the chance of 2 dwarfs that are heterozygous for the disease to have a child that is normal sized?

9 Recessive Human Diseases
Not having disease is dominant over having the disease Have to inherit the recessive allele from both parents (i.e. 2 little letters) A person can be a CARRIER (heterozygous) for the disease and not show symptoms If two carriers have a child, the child has a 25% chance of having the disease A child can have it without either parent having it

10 Cystic Fibrosis Inheritance Pattern: Recessive Symptoms:
Overproduction and build-up of mucus in lungs and digestive tract Difficulty breathing Salty skin

11 Cystic Fibrosis (cont.)
Other Important Information: Avg. life expectancy 30 – 40 years Most common genetic disease in white Americans Treatment: physical therapy, gene therapy, special diet

12 Gene Therapy

13 Example Problem: A child’s mom is completely normal. His dad is a carrier for CF. What is the chance that the child will also be a carrier?

14 Tay-Sachs Inheritance Pattern: Recessive Symptoms:
Lipids accumulate in cells of CNS Loss of motor skills, blindness, paralysis, death

15 Tay-Sachs (cont.) Other Important Information:
Life expectancy = 5 years Most common in Jews and Amish

16 Example Problem Two carriers for Tay-Sachs have a child. What is the chance that the child will have Tay-Sachs?

17 Phenylketonuria (PKU)
Inheritance Pattern: Recessive Symptoms: a.a. phenylalanine accumulates in body and damages CNS → brain damage Now can be detected at birth before brain damage occurs

18 PKU (cont.) Other Important Information: Treatment:
Babies – diet low in milk until brain is fully developed Pregnant women – limit milk, diet foods, protein

19 Example Problem: A woman has PKU. A man is completely normal. What is the chance of their child having PKU?

20 Albinism Inheritance Pattern: Recessive Symptoms:
Little or no pigment (melanin) in eyes, skin, hair Most have blue eyes, pale skin, and blond hair Vision problems

21 Albinism (cont.) Other Important Information:
Have to be careful of sun exposure

22 Example Problem: Is it possible for 2 albino people to have a child with normal pigment?

23 Other Weird Genetic “Conditions”
Vadoma Tribe – Zimbabwe - Ostrich-toed (ectodactyly) Blue people of Troublesome Creek Result from lack of an enzyme Causes abnormal hemoglobin


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