GENETIC DISORDERS

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GENETIC DISORDERS
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Two Types of Mutations

• Gene mutation single gene defective
• Insertion
• Substitution
• Deletion
• Chromosomal mutation missing or extra chromosome
• Monosomy
• Trisomy
• Deletion
• Either can involve autosomes (chromosomes 1-22)
  or sex chromosomes

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Autosomal Disorders

• Disorders involving the 22 pairs of chromosomes
  that are NOT sex chromosomes (X,Y).
• Can result from
• Gene mutation defective gene
• on autosome
• Chromosomal mutation loss
• or gain of autosome

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Autosomal DisordersGene Mutations

• 1- Cystic Fibrosis
• Recessive disorder
• Mutated gene on chromosome 17.
• Characterized by excessive, THICK secretion of
  the mucus in the body.

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Autosomal DisordersGene Mutations

• 2- Huntington Disease
• Dominant disorder
• Mutated gene on chromosome 4 is responsible.
• Causes degeneration of neurons producing
  dementia, and random jerking movements.

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Autosomal DisordersGene Mutations

• 3- Phenylketonuria (PKU)
• Recessive disorder
• Mutated gene on chromosome 12 is responsible
• 4- Sickle-Cell Anemia
• 1 of 12 U.S. African Americans
• Recessive disorder
• Mutated gene on chromosome 11

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Autosomal DisordersGene Mutations

• 5- Tay-sachs Disease
• Recessive disorder
• European Jewish ancestry.
• Mutated gene on chromosome 15
• Tay-sachsOne Wrong Letter

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Autosomal DisordersChromosomal Mutations

• Down Syndrome
• 1 in 1,000 live births.
• Extra Chromosome 21
• Risk increases with moms age
• Pregnancies of women
• over age 35 accounts for
• 20 of Down syndrome
• births

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Sex-Linked Disorders

• Involve the sex chromosomes
• Recessive gene on the X chromosome is more likely
  to be expressed in males
• Y chromosome has no 2nd allele that might
  counteract the gene on the X chromosome!

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Sex-Linked DisordersGene Mutations

• 1- Color Blindness
• X-linked recessive disorder
• Gene mutation on X chromosome
• 1 of 10 males
• 2- Hemophilia
• X-linked recessive disorder
• Gene mutation on X chromosome.
• 1 of 5,000 males
• Interfere with normal blood clotting

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Sex-Linked DisordersChromosomal Mutations

• 1- Klinefelter Syndrome (XXY)
• 1 of 1,000 males.
• Extra X chromosome

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Sex-linked DisordersChromosomal Mutations

• 2- Turners Syndrome (XO)
• 1 of 10,000 females
• One of X chromosomes is either missing or
  inactive
• Have immature female appearance and lack internal
  reproductive organs.

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GENETIC DISORDERS
Autosomal Disorders Chromosomes 1-22
Sex-Linked Disorders Sex Chromosomes X and Y
Gene Mutations 1 gene mutated on chromosomes 1-22
Chromosomal Mutations Extra or missing
chromosome 1-22
Gene Mutations 1 gene mutated on X chromosome
Chromosomal Mutations Extra or missing Sex
chromosome
EXAMPLES?
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How Do We Know About All of Our Genes?

• Human Genome Project
• Began in 1990
• Goals
• Determine complete sequence of the 3 billion DNA
  bases in human DNA
• Identify all human genes for further biological
  study

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The Unknown

• Gene number, exact locations and functions
• Gene regulation
• DNA sequence organization
• Chromosomal structure and organization

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Ethical, Legal and Social Issues

• Fears
• Genetic information used to harm or discriminate
• Deny access to health insurance
• Deny employment
• Deny education
• Deny loans?
• Cloning?
• DNA Databases

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Cloning

• Creating many
• genetically identical cells
• from one cell.
• Creation of genetically
• identical organisms

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Biotechnology
Dolly and surrogate Mom
Embryonic stem cells and gene therapy
Genetically modified rice.
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Why Clone Animals?
Five genetically identical cloned pigs.
To answer questions of basic Biology
For pharmaceutical production.
For herd improvement.
To satisfy our desires (e.g. pet cloning).
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Is Animal Cloning Ethical?
The first cloned horse and her surrogate
mother/genetic twin.
As with many important questions, the answer is
beyond the scope of science.