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Genetic Disorders & Karyotypes

This review offers insights into genetic disorders and karyotypes, highlighting the complexity of traits that are often polygenic, influenced by multiple genes. Environmental factors can alter traits, but the underlying genetic code remains vital. The text explains the role of alleles and chromosomes in genetic inheritance, and outlines the importance of genetic screening methods, such as karyotyping and blood tests. It discusses various genetic disorders, like Down syndrome and Marfan syndrome, their characteristics, and potential treatments including gene therapy and lifestyle adjustments.

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Genetic Disorders & Karyotypes

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  1. Genetic Disorders & Karyotypes • Review for field trip

  2. Traits • Most of your traits or characteristics are “polygenic” - means several genes are involved • Ex. skin color, hair color, height, eye color

  3. Environment • Environmental factors CAN influence your traits (better nutrition, disease) but traits are determined by genes.

  4. Alleles • Single allele - 2 or more alternate forms of 1 gene • Ex. RR, Rr, or rr - each is an allele for flower color • Multiple alleles - 3 or more alternate forms • Ex. Blood type - A, B, AB, or O = allele possibilities

  5. Chromosomes/Genes • Homologous pairs - 1 from mom, 1 from dad • Have similar alleles on each; slightly different molecular forms • Bands = gene location for a particular allele

  6. Genetic Disorders • Occur based on problems originating on a gene • Over 200 types

  7. Genetic screening • Can be done if you have a history of genetic disorders in your family • Uses: karyotypes, blood tests for proteins, DNA testing

  8. Karyotypes • Shows unduplicated chromosomes - 1 from mom, 1 from dad • Can “easily” see problems

  9. Trisomy 21 • Has 2 chromosomes located at position #21 • Down syndrome

  10. Trisomy 18 • Rick Santorum’s child • 3 chromosomes at #18 position

  11. Marfan syndrome • Extremely long arms, legs and torso; spider like fingers • Disorder of connective tissue

  12. Angelman syndrome • Similar to autism or cerebral palsy • Lack of speech, seizures, balance disorder, need life long care • General “angel” like personality - happy, outgoing, smiling

  13. Other screening types • Amniocentesis - at 14th to 16th week of pregnancy • Common: women 35+ • Needle in belly button to withdraw amniotic fluid to examine chromosomes and proteins

  14. Other screenings • Chorionic villi sampling (CVS) - takes cells from developing fetus (zygote) at 8-10th weeks.

  15. Table 12-1 pg. 246 • Some common genetic disorders • Will be doing a project on a disorder soon

  16. Treatment • Genetic counselor - works with parents to determine probability of genetic disorder in their offspring • Pedigree = family tree

  17. Treatment • Can sometimes alter diet if an enzyme is missing • Cystic fibrosis - pounding on back to loosen mucuous; ventilator • Hemophilia - drugs for blood clotting • Surgery in utero

  18. Gene therapy • Placing healthy copy of gene into cells of person who has defective gene. • Have to know sequence of genes (bases) that are defective.

  19. Gene therapy • 1. Healthy gene inserted into the DNA of a virus • 2. Virus inserted into lungs of patient • 3. Virus infects cells • 4. Healthy gene is now in cells; can make proteins that were missing • Is temporary - have to repeat

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