Pedigree Analysis

  1. Autosomal Dominant
    • 1. All affected individuals should have at least one affected parent
    • 2. Males and Females are affected in about equal numbers
    • 3. Both Males and Females Transmit the Trait
    • 4. Most affected individuals are heterozygous. 50% of union between unaffected and normal are affected
    • 5. Two affected individuals have a 25% chance of having an unaffected child
    • 6. The trait will not reappear in the descendents of two unaffected individuals
    • 7. The state may be more severe or even lethal in the homozygous trait
  2. Marfan Syndrome
    Autosomal dominant. Caused by a defective gene for fibrillin important for the structure of bone and major blood vessels.
  3. Familial Hypercholesterolemia
    Autosomal Dominant. Caused by a defective LDL receptor, LDL Carriers the cholesterol to the cell.
  4. Autosomal Recessive
    • 1. The trait is expressed in both sexes and is transmitted by either sex to both the male and female offspring in roughly equal numbers
    • 2. Most affected individuals are the children of unaffected parents.
    • 3.. Matings between an affected and unaffected individual will usually result in ALL normal offspring.
    • 4. When both parents are affective all of their children are affected.
    • 5. Matngs between unaffected heterozygotes yeild about 3/4 unaffected and 1/4 affeted offspring.
  5. Cystic Fibrosis
    Autosomal Recessive. Defective gene that controls salt and water transport from cells that line tube-like structures in the body. Organ Malfunction, can't control water flow to the body.
  6. Sickle Cell Anemia
    Autosomal Recessive. Defect in the genee for hemoglobin, the oxygen carrying molecule of the blood
  7. X-Linked Dominant Inheritance
    • 1. There is no male to male transmission of the trait. Y chromosone is not involved
    • 2. All daughters of an affected male are affected.
    • 3. Affected females (probably heterozygous) mated to unaffected males produce offspring where one half the sons and daughters are affected
    • 4. Males are more severly affected than females.
    • 5. Expression of the trait is more variable in females. Due to inactivation of one of the x chromosones.
    • 6. In general there are twice as many females affected than males. Females have two x chromosones
  8. Hypophosphatemia
    X-Linked Dominant. Low phosate and clalcium in the blood caused by a defect in the kidney transport system.
  9. X-Linked Recessive
    • 1. Phenotypic expression is much more commin in males than females--> sex linkage
    • 2. Father to son inheritance is never seen--> this rules out Y and makes autosomal transmission unlikely
    • 3. An unaffected mother, matting an unaffected male can pass the trait to 1/2 of her sons. The trait will not be observed in her daughters.--> x-linked transmission and trait is recessive
    • 4. Carrier females often have affected male relatives and or female carrier ancestors
  10. Red/ Green Color Blindness
    X-linked recessive. A defect in the color sensing mechanism of the eye.
  11. Duchenne Muscular Dystrophy
    X-linked recessive. Progressive muscle weakness and wasting.
  12. Hemophilis
    X-linked recessive. Inability of the blood to clot, this will result in excessive blood loss.
  13. Y-Linked Inheritance
    • 1. The Trair phenotype is only in males and passed only to males
    • 2. All of the sons of an affected male show the trait.

    this may appear in sexual development
  14. Mitochondrial Inhertiance
    Inheritance is from Mothers to all offsprings. Males make no contribution. Issues in energy generation.
  15. Expressivity
    The range of phenotypes resulting from a given genotype
  16. Penetrance
    the probability that a disease trait will appear when a disease-related gentotype is present. Interaction between gene and environment and also other genes.
  17. Genetic Linkage
    Co-Inheritance of genes that physically reside on the same chromosone
  18. Crossing Over
    During Meiosis when material is swapped
Card Set
Pedigree Analysis
Pedigree Analysis Exam