Autosomal Genetic Diseases

1. Autosomal Genetic Diseases Biology

2. Autosomal Genetic Diseases • The majority of human genetic disorders, are carried on the autosomes, which are all the chromosomes except the sex chromosomes • Many of these diseases can be detected in the womb by withdrawing a small amount of fluid from the sac surrounding the fetus- called an amniocentesis

3. Autosomal Genetic Diseases • Another method of testing for diseases is to remove tissue surrounding the fetus-chorionic villus sampling • Because many of these diseases are not treatable, it becomes a moral and ethical issue whether or not to even test for them

4. Albinism • This is a genetic disorder caused by a recessive allele on chromosome 11 • Individuals who have two copies of this allele are unable to produce melanin, the pigment responsible for human skin color • These individuals are very sensitive to light and must avoid excessive exposure to bright light

5. Cystic Fibrosis • In the US, this is the most common genetic disease, it found in people of European ancestry and affects approximately 1 child in every 2500 • This disorder is caused by a recessive allele on chromosome 7

6. Cystic Fibrosis • Individuals with this disorder make a defective cell membrane protein that interferes with cell movement of chloride ions into and out of the cell, soon the chloride ions begin to build up inside the cells causing water from the surrounding liquid to enter the cells,

7. Cystic Fibrosis • the surrounding liquid becomes thick and heavy, clogging the lungs and breathing passageways

8. Tay-Sachs Disease • Tay-sachs disease is a fatal genetic disorder caused by a recessive allele • This disorder is most common in Jewish families of Eastern European ancestry • Children born with the disorder suffer from a rapid breakdown of the nervous system beginning at age 2 or 3

9. Sickle-Cell Anemia • This is a blood disorder that is characterized by crescent, or sickle-shaped, red blood cells • It is caused by a recessive allele that produces an alternate form of hemoglobin, which is the red blood cell protein • Sickle-cell anemia is common in parts of the world where malaria is common

10. Sickle-Cell Anemia • Individuals with two copies of the sickle cell allele suffer from sickle cell anemia and have serious medical problems, people who are heterozygous for the sickle cell allele are generally healthy and they have the benefit of being resistant to malaria

11. PKU • One in every 15,000 children is born with phenylketonuria, a genetic disorder caused by a recessive allele • PKU can cause severe mental retardation, fortunately there is a test and a treatment for PKU and most states require all newborn infants to be tested for PKU

12. PKU • A diet low in phenylalanine and high in tyrosine can be a very effective treatment • Individuals with PKU are not able to produce the enzyme phenylalanine hydroxylase (PAH) • This enzyme metabolizes the amino acid phenylalanine to the amino acid tyrosine

13. Huntington Disease • This is a rare genetic disorder carried by a dominant allele located on chromosome 4 • Most individuals have no symptoms until their late 30’s and 40’s, when they begin to lose control of their muscles, as the diseases progresses the nervous system breaks down, most die within 15 years after symptoms first appear

14. Huntington Disease • Because this disorder appears in middle age, most people at risk for the disorder have already had children when they find out that they carry the allele