1. Human Genetic Disorders

2. What are Genetic Disorders?
Genetic disorder- an abnormal condition that a person inherits through genes or chromosomes
Genetic disorders are caused by mutations
The mutation may occur when sex cells form or may be passed down from parent to offspring

3. Cystic Fibrosis
Body produces abnormally thick mucus in the lungs and digestive system
Symptoms:
Difficulty breathing
Bacteria in lungs can cause infections
Digestive problems
Mutation is caused by a recessive allele
Most common in people of northern European descent
Currently no cure
Treatment:
drugs to prevent infection
physical therapy

4. Sickle-Cell Disease
Red blood cells are sickle shaped, resulting from abnormal production of the protein hemoglobin
Hemoglobin is responsible for carrying oxygen in the blood
Symptoms:
Lack of oxygen in the blood
Pain and weakness
Most common in people of African descent
Currently no cure
Treatment:
Drugs to relieve symptoms and to prevent blockages in veins

5. Hemophilia
A genetic disorder in which a person’s blood clots very slowly or not at all due to a missing protein
Potential to bleed to death from small cuts or minor bumps and bruises
Caused by a recessive allele on the X chromosome
Occurs more frequently in males
Treatment:
Regular doses of missing protein
Avoid contact sports

6. Huntington’s Disease
A genetic disease that causes the gradual breakdown of cells in the brain
Caused by a dominant allele
Is a fatal disease with no cure
Symptoms appear around age 30

7. Down Syndrome A genetic disorder caused by an extra chromosome 21
The extra chromosome is a result of an error during meiosis
Symptoms:
Distinctive physical appearance
Some degree of mental retardation
Heart defects

8. Diagnosing Genetic Disorders
Scientists use tools such as
Amniocentesis
Doctor uses a long needle to remove fluid surrounding the baby
Fluid contains cells that are analyzed in a karyotype
Karyotypes
A picture of all the chromosomes in a cell
Doctors arrange chromosomes in pairs
Look for correct number and shape of
chromosomes
Can be used to determine sex of baby

9. Genetic Counseling
People may have genetic counseling if they have a history of genetic disorders in their families
Genetic counselors use karyotypes, pedigree charts, and Punnett squares to determine a couple’s chances of having a child with certain genetic disorders