Human Genetic Disorders

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Human Genetic Disorders

• Mrs. Kerstetter
• General Science 7

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Section 2 Objectives

• Describe the causes and symptoms of 5 human
  genetic disorders.
• Explain how genetic disorders are diagnosed.
• Describe the role of genetic counselors.

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Genetic Disorders

• abnormal condition that a person inherits
  through genes or chromosomes
• Caused by MUTATIONS, or changes in persons DNA.
• Causes
• Mutation during meiosis (sex cells)
• Mutation passed from parent

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Cystic Fibrosis

• Body produces really thick mucous in lungs and
  intestines
• Makes it hard to breathe and to digest food
• Carried on a RECESSIVE allele
• Risk North European ancestors
• No cure, just treatment

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Sickle-Cell Disease

• Affects the production of HEMOGLOBIN in the blood
  (RBCs)
• Causes blood cells to be sickle-shaped
• Hemoglobin cant carry enough oxygen when RBCs
  are deformed
• Causes pain and weakness

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Sickle-Cell Disease

• Most common in African ancestry
• Allele is CODOMINANT
• Currently, no cure
• Treatment of pain and prevent blockages in blood
  vessels

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Hemophilia

• Blood clots very slowly
• Do not produce protein for normal clotting
• Can bleed to death, bruise easily
• RECESSIVE allele on X chromosome
• Treatment regular doses of missing protein

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Huntingtons Disease

• Caused by DOMINANT allele
• Every person who inherits the allele will develop
  Huntingtons disease
• Fatal
• Symptoms appear after 30 years of age

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Down Syndrome

• Extra copy of CHROMOSOME 21
• Usually error during meiosis
• Distinct physical appearance, some degree of
  mental retardation, heart defects

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Diagnosing Genetic Disorders

• Tools to diagnose
• Punnett Squares
• Pedigrees
• Amniocentesis
• test cells from fluid surrounding baby
• - Uses big needle
• Karyotypes
• picture of chromosomes in a cell

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Genetic Counseling

• Help couples understand chances of having a child
  with a genetic disorder
• Determines probability ( chance)
• Uses Punnett Squares, pedigrees, amniocentesis,
  karyotypes