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Pedigrees - PowerPoint PPT Presentation

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Pedigrees. & Genetic Disorders. What is a Pedigree?. Show the genetic history of a family “ Genetic Family Tree “ Shows phenotypes one generation to the next Sometimes shows genotypes from one generation to the next;

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& Genetic Disorders

What is a pedigree
What is a Pedigree?

  • Show the genetic history

    of a family

  • “Genetic Family Tree“

  • Shows phenotypes one

    generation to the next

  • Sometimes shows

    genotypes from one

    generation to the next;

    and sometimes you can figure out the genotype based on your knowledge of inheritance


The Weasley Family Tree

Pedigree example
Pedigree Example

FF= Free hanging ears

Ff= Free hanging ears

ff= Attached ears

  • each generation is represented using a Roman Numeral

  • circles are females, squares are males

  • a line connecting two shapes indicated a mating

  • shaded in areas indicate an individual affected by the trait














Pedigree example1
Pedigree Example

What do you see?

Who cares about pedigrees
Who cares about pedigrees?

  • Pedigrees tell the phenotypic/genotypic story:

    • Who bred with who? (i.e. Any new traits introduced?)

    • What was the relationship between relatives?

      (i.e. Third cousins once removed)

    • What traits were passed on? (i.e. Hanging ears or Sickle Cell Anemia)

  • So who would cares?

What is a genetic disorder
What is a genetic disorder?

  • A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes.

    (The University of Utah, 2013)

Common Misconception Alert! Genetic disorders are all inherited.


Levels of genetic disorders
Levels of Genetic Disorders

  • Level 1: Single Gene Disorders

    • Mutation of a single gene cause protein to be altered or deleted

  • Level 2: Chromosome Abnormalities

    • Entire chromosomes or large segments are deleted, duplicated or altered

  • Level 3: Multifactorial Disorders

    • Mutations in multiple genes, often coupled with environmental factors

(The University of Utah, 2013)

Factors of genetic disorders
Factors of Genetic Disorders

  • Stress

  • Diet

  • Physical/Mental Abuse

  • Drugs and Alcohol

  • Exposure to Radiation, Pathogens, Toxins and Chemicals

  • E.g. A person exposed to head injuries may be more likely to develop Alzheimer’s.

  • Family Medical History

    • 1st, 2nd and 3rd generation

    • Skipped Generations

    • Carriers

  • Autosomal Dominant/ Recessive

  • X-Linked Dominant/ Recessive

  • Mitochondrial (paternal mtDNA)

  • E.g. Huntington’s Disease is an AutosomalDominant disease, and thus every generations will be affected by it.



Common genetic disorders and their mutations
Common Genetic Disorders and Their Mutations

  • Down’s Syndrome: Trisomy 21

  • Klinefelter Syndrome: XXY

  • Turner Syndrome: XO

  • Fragile-X Syndrome: X-Linked Dominant ( FMR1)

  • Duchenne Muscular Dystrophy: X-Linked Recessive (DMD gene)

  • Huntington’s Disease: Autosomal Dominant (HTT gene)

  • Tay Sachs: Autosomal Recessive (HEXA gene)

  • Cystic Fibrosis: Autosomal Recessive (CFTR)

  • Sickle Cell:Autosomal Recessive (HBB gene)


Royal Family Pedigree

(X-linked recessive)

Sickle cell
Sickle Cell

  • Autosomal Recessive

  • Blood Disorder

  • Some Symptoms: anemia, fever, chest pain, increased risk of infections, especially respiratory infections, death


Sickle cell and malaria
Sickle Cell and Malaria

  • Malaria:

    • Vector-borne disease, parasites are transmitted by mosquitoes through blood

    • Symptoms include fever, chills, flu-like illness, may cause death

    • In 2010 an estimated 216 million cases of malaria occurred worldwide and 655,000 people died, most (91%) in the African Region (CDC, 2010)

  • Sickle Cell

    • Carriers have increased resistance against malaria

    • 60% protection against overall mortality


Sickle cell anemia
Sickle Cell Anemia

= Unaffected Individuals

= Carriers of the disease

= Affected by the Disease