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Mapping Mendelian Traits in Humans Part I

Mapping Mendelian Traits in Humans Part I. Linkage and Markers Informative Meioses Phase Known Pedigrees Case Study: Nail Patella Syndrome. Important Pre-Reading Concepts. Text Reading There is a Human Gene Mapping handout on the Website that covers the next two lectures.

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Mapping Mendelian Traits in Humans Part I

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  1. Mapping Mendelian Traits in Humans Part I • Linkage and Markers • Informative Meioses • Phase Known Pedigrees • Case Study: Nail Patella Syndrome

  2. Important Pre-Reading Concepts • Text Reading • There is a Human Gene Mapping handout on the Website that covers the next two lectures. • Important Pre-Lecture Concepts (quiz material) • Review Mini- and Micro-satellites, Types of alleles at these loci, and how you can use PCR to identify the alleles • Class Discussion • What is a marker? • What makes a pedigree useful for linkage mapping? • What makes a pedigree not useful for linkage mapping? Think about these topics as we go through the lecture and come back to them as you go over the lecture material and practice problem solving.

  3. Mapping Mendelian Traits in Humans:Linkage

  4. Mapping Mendelian Traits in HumansPhysical Maps and Markers Markers: Other Genes Single Nucleotide Polymorphisms Micro-satellites (STRs, Dinucleotide Repeats)*** Mini-satellites (Larger Repeats-VNTRs)

  5. Mapping Mendelian Traits in HumansExamples of microsatellite markers GA repeat GAGT repeat Marker Locus Allele name Size of the Repeat Blumenfeld et al., Am. J. Hum. Genet. 64:1110–1118, 1999

  6. Mapping Mendelian Traits in Humans: General Case of Dominance in a Pedigree

  7. Mapping Mendelian Traits in Humans:Marker Segregating Independently of Trait

  8. Mapping Mendelian Traits in Humans:Marker Co-segregating with Trait

  9. Mapping Mendelian Traits in Humans:Informative vs Uninformative Meioses Uninformative A1A1 A2A2 A1A2 A1A2 A1A2 A1A2 Informative A1A2 A1A2 A1A2 A3A4 A1A1 A1A4 Key Point :Best to have a marker/gene with several alleles

  10. Mapping Mendelian Traits in Humans:Phase Known vs Phase Unknown Phase Known Phase Unknown A2A5 A1A6 A1A2 A1A2 A3A4 A3A4 A1A3 A2A3 A1A4 A1A4 A2A4 A1A3 A2A3 A1A4 A1A4 A2A4 A2A3 A2A3 A1 travels with the disease • Is it A1 or A2 traveling with the disease • Which are recombinants? Recombinant

  11. Case study of Linkage: Nail-patella syndrome • Autosomal Dominant: Abnormal Fingernails and Absent or Rudimentary Kneecaps • Linkage was demonstrated with the ABO Blood type locus Recombinant

  12. Case Study of Linkage:What is the inheritance of the two traits? • Nail-patella syndrome - (affected individuals indicated by filled symbols) - dominant • Blood Type - A and B codominant and each dominant to O

  13. Case Study of Linkage:A Human Dihybrid Cross Np__ npnp Npnp npnp

  14. Case Study of Linkage:Analyzing the Pedigree • Is this cross informative? • Are there any linkage associations evident? • Are there any recombinant individuals in the pedigree?

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