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Human Genetic Disorders

Human Genetic Disorders. Harmful or Beneficial?. Human Genetic Disorders. Mutations are key DNA change  change in alleles Chromosomal errors  nondisjunction Deletion, inversion, translocation. Disorders may be…. In germ cells or somatic cells Dominant or recessive

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Human Genetic Disorders

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  1. Human Genetic Disorders Harmful or Beneficial?

  2. Human Genetic Disorders • Mutations are key • DNA change  change in alleles • Chromosomal errors  • nondisjunction • Deletion, inversion, translocation

  3. Disorders may be… • In germ cells or somatic cells • Dominant or recessive • Autosomes or Sex linked

  4. Many inherited disorders in humans are controlled by a single gene Normal Dd Normal Dd PARENTS • Most such disorders are caused by autosomal recessive alleles • Examples: cystic fibrosis, sickle-cell disease D D Eggs Sperm DD Normal d d Dd Normal (carrier) Dd Normal (carrier) OFFSPRING dd Deaf Figure 9.9A

  5. Examples: achondroplasia, Huntington’s disease • A few are caused by dominant alleles Figure 9.9B

  6. Table 9.9

  7. Tracking Traits & Prediction • Before mating • Genetic screening - karyotype • Punnets • Pedigree analysis

  8. Family pedigrees are used to determine patterns of inheritance and individual genotypes Dd Joshua Lambert Dd Abigail Linnell D_ JohnEddy ? D_ HepzibahDaggett ? D_ Abigail Lambert ? dd JonathanLambert Dd Elizabeth Eddy Dd Dd dd Dd Dd Dd dd Female Male Deaf Hearing Figure 9.8B

  9. Genetic testing • Fetal cells can be obtained through amniocentesis Amnioticfluidwithdrawn Centrifugation Amnioticfluid Fluid Fetalcells Fetus(14-20weeks) Biochemicaltests Placenta Severalweeks later Figure 9.10A Uterus Cervix Karyotyping Cell culture

  10. After fertilization • Amniocentesis • Chorionic villi sampling • Protein tests/biochemical tests via urine samples • Ultrasound (sonogram) • **Genetic counseling for all**

  11. Chorionic villus sampling obtains fetal cells for karyotyping Fetus(10-12weeks) Several hourslater Placenta Suction Karyotyping Fetal cells(from chorionic villi) Some biochemical tests Chorionic villi Figure 9.10B

  12. Uultrasound (sonogram) Figure 9.10C, D

  13. Risks to consider: • Harm to baby • Invasive, risk of miscarriage • Harm to mother • Invasive, risk of infection • Ethical, moral, personal decisions

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