Genetic disorders

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Genetic disorders

  1. 1. Genetic Disorders  A genetic disorder is caused by a mutation to a gene, group of genes, or entire chromosome.  Remember, genes carry instructions to build proteins.  When these instructions are mutated, proteins can’t get build correctly.  Genetic disorders generally occur in two different varieties. a) Chromosomal defect (chromosomal mutations) b) Gene defect (gene mutations)
  2. 2. Gene Defects  Gene defects occur when an individual gene is mutated on a chromosome.  Since only one gene is affected, usually only one protein is affected. Ex.) hemophilia  Many gene defects can be inherited, however, many of them can occur spontaneously (without being inherited) through being exposed to mutagens like chemicals or radiation.
  3. 3. Inheriting a Gene Defect  There are generally three different patterns of inheritance. a) Autosomal recessive b) Autosomal dominant c) Sex linked recessive
  4. 4. Sex chromosomes
  5. 5. Autosomal Recessive Inheritance  Ex.) Cystic Fibrosis  Caused by a recessive allele on chromosome #7.  FF – normal Ff – carrier (normal) ff – disease  Two parents that are both carriers for CF, want to know the chance of having a child with CF? FF Ff Ff ff F F f f
  6. 6. Autosomal Dominant Inheritance  Ex.) Huntington’s Disease  Caused by a dominant allele on chromosome #12.  HH – lethal in embryo  Hh – Huntington’s disease  hh – normal  One member of a couple has Huntington’s, what is the chance of their children having the disease? Hh hh Hh hh H h h h
  7. 7. Sex Linked Recessive Inheritance  Ex.) Hemophilia  Caused by recessive allele on the X chromosome  XHXH - Normal female  XHXh - Carrier female  XhXh - Hemophiliac female  XHY - Normal male  XhY - Hemophiliac male  Cross a carrier female with a normal male? What are the possibilities in their children? XHXH XHXh XHY XhY XH Xh XH Y
  8. 8. Chromosomal Defects  Some genetic disorders are caused by defects to an entire chromosome.  Ex.) Monosomy – a chromosome is missing. Trisomy – having an extra chromosome.  Sometimes only pieces of chromosomes are affected.  Ex.) Inversion, deletion, translocation.  Chromosomal defects generally affect many proteins because so many genes are affected on the chromosome.  Many of these defects lead to miscarriages.
  9. 9. How are chromosomal mutations detected? Karyotyping A set of chromosomes 46 chromosomes in a human karyotype (23 pairs).
  10. 10. What can be determined from looking at a karyotype? 1. Sex of the individual. 2. Chromosomal mutations (abberations) a) Monosomy (missing a chromosome) b) Trisomy (extra chromosome) c) Deletions (section of chromosome missing) ***Depending which chromosome has the mutation, this determines the disorder…
  11. 11. Karyotype
  12. 12. Evaluate the Karyotype…
  13. 13. Evaluate the Karyotype…
  14. 14. Evaluate the Karyotype…
  15. 15. Evaluate the Karyotype…

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