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Allele Important Genetic Concepts Genotype Phenotype Gene.

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Presentation on theme: "Allele Important Genetic Concepts Genotype Phenotype Gene."— Presentation transcript:

1 Allele Important Genetic Concepts Genotype Phenotype Gene

2 Mutation (Chapt. 16) Classification of Mutations Mechanisms of Mutagenesis DNA Repair Pathways

3 Possible Reading Frames for RNA

4 A Comprehensive Catalogue of Somatic Mutations From a Cancer Genome Nature (December 2009) Cancer: Malignant Melanoma Total base substitution mutations: 33,345 Coding mutations: 292 Missense: 172 Nonsense: 15 Silent:105 Total Chromosome mutations: 37

5 Old DNA Replication Pg. 279 Template-dependent Semi-conservative 5’ to 3’ Synthesis Old New

6 Standard Base Pairs Tautomeric Shift Base Pairs AT G C T G G T AC CA Rare tautomers are shown in Red

7 Tautomeric Shift of “A” DNA molecule with TA CG transition mutation Affected base pair Pg. 416

8 Oxidation of Guanine 8-oxo-7,8-dihydro-guanine (8-oxoG) ( OH) OHProduced From Electron Transport

9 8-oxoG-A Base Pair 8-oxoG Adenine

10 Insertion by “Looping Out” of Newly Synthesized Strand

11 Deletion by “Looping Out” of Template Strand

12 Intercalating Agents Ethidium Bromide

13 Ethidium Intercalation in DNA


15 Medical Diagnostics X-rays, positrons Radiotherapy X-rays, gamma rays

16 Pg. 419

17 Pyrimidine Dimer

18 (NER) Individuals that are homozygous for loss-of-function alleles of one of the XP genes UV Nucleotide Excision Repair (NER) Pathway (pyrimidine dimer)

19 (NER) Damaged DNA Replicated Mutations! UV Nucleotide Excision Repair (NER) Pathway (pyrimidine dimer) Individuals that are homozygous for loss-of-function alleles of one of the XP genes

20 Xeroderma pigmentosum

21 Sickle Cell Anemia Sickle Cell Trait Normal Red Blood Cells

22 Hemoglobin ß-globin (146 amino acids) ß-globin (146 amino acids)

23 Molecular Genetics of Sickle-Cell Anemia Hb-A Hb-S Codon #6 Normal Individuals Sickle Cell Individuals E6V

24 Hb-S Deoxyhemoglobin

25 Polymerized Deoxyhemoglobin (tactoids)

26 Molecular Genetics of Sickle-Cell Anemia Hb A Allele Hb S Allele Hb-A Hb-S Codon #6

27 Hb-A WT and Mutant ß-globin Proteins Hb Mutant Proteins Hb WT Protein

28 Huntington’s Disease

29 Mutant Huntingtin Protein Aggregates Transmission Electron Micrograph

30 WT Huntingtin-GFPMutant Huntingtin-GFP

31 hhHhHH No Htt Protein Aggregates Htt Protein Aggregates No HDHD

32 Trinucleotide Repeat Diseases

33 Cystic Fibrosis

34 CFTR Protein

35 Missense mutation Nonsense mutation Frame-shift mutation Deletion, in-frame CFTR Gene Mutations Loss-of-Function Mutations ~1200 pathological mutations Spectrum of Mutations in CFTR Gene

36 Frequency of CF Mutant Alleles ~ 70% of CF Mutant alleles are ∆F508

37 ∆F508 Mutation

38 Healthy Lung Lung epithelial cells Lung epithelial cells AA or Aa

39 Lung epithelial cells Lung epithelial cells Cystic Fibrosis Lung aa

40 Erythropoietin Receptor Mutation And Olympic Glory Seven Olympic medals Eero Mäntyranta

41 (Epo)

42 Erythropoietin (Epo)

43 Red Blood Cell Development

44 Genetic Testing Disease-related Diagnosis Current disease Risk of future disease Carrier status Pharmacogenomics Efficacy of therapeutic drug treatment Tissue Typing Transplantation

45 Genetic Testing for Sickle Cell Anemia Hb S Hb A Pg. 644 MstII cut sites

46 “Prodrug” Tamoxifen Bioactive form of Tamoxifen OH Cytochrome P450 (CYP2D6)

47 Cytochrome P450 (CYP2D6) ~ 10% Caucasians are “poor” metabolizers

48 Genetic Testing for Tissue Typing Silent Mutations mmmmmmm Missense

49 Early Embryonic Development (~ 7 days)

50 In Vitro Fertilization (IVF) Sperm cells Embryos (4-cell stage) Oocytes

51 Pre-implantation Genetic Diagnosis (PGD) 8-cell Embryo

52 Removal viral genes Splice in WT Allele Viral Vector for Gene Therapy WT Allele aaaaa

53 Gene Therapy Vectors Retroviruses (e.g. MLV, HIV) Adenoviruses Herpes viruses Cell Host Range Dividing vs. non-dividing cells Overall efficiency of transfer “Evolved” virus

54 Hematopoietic Stem Cell Gene Therapy with a Lentiviral Vector in X-Linked Adrenoleukodystrophy Science 6 November 2009: Vol. 326. pp. 818 - 823 Cartier et al (26 authors!)

55 X-Linked Adrenoleukodystrophy (ALD) Monogenic Recessive Loss-of-function mutations in ABCD1 gene Defective transport of “very long chain fatty acids” to peroxisomes Multifocal demyelination of CNS cells 1/17,000 newborn boys are affected

56 Myelinated Neuron Schwann Cell Myelin

57 Hematopoietic Stem Cells (HSCs)

58 Brains of ALD Patients Untreated HSC Therapy

59 Gene Therapy for Cancer

60 Thymidine Kinase Cytosine Deaminase Nitroimidazole reductase GanciclovirPhosphoganciclovir 5-fluorocytosone5-fluorouracil CB1954Alkylating agent EnzymeProdrugToxic Metabolite Gene Therapy for Cancer

61 M-Phase Chromosome Interphase (G1, S, G2) Chromosomes

62 Giemsa Stain

63 Human Euploid Karyotypes FemaleMale Fig. 7-6

64 Homologous Chromosomes PM P = Paternal M = Maternal

65 2001

66 Human Genome Information

67 “Raw” DNA sequence Where are the genes?

68 3000 bp scanned for ORFs 5’ 3’ Three Reading Frames Three Reading Frames


70 Y58 Mbp397 5 2 13 3 6 4 7 8 9 11 10 14 12 15 16 17 19 20 18 21 X 22 1 ChromosomeDNA sizeORF #ChromosomeDNA SizeORF # 155 Mbp1606 83550 Mbp 47 Mbp425 62 Mbp857 64 Mbp1992 76 Mbp517 79 Mbp1714 89 Mbp1318 100 Mbp1202 106 Mbp1453 3380247 Mbp 243 Mbp2204 1760200 Mbp 191 Mbp1361 181 Mbp1536 1959171 Mbp 159 Mbp1764 1247146 Mbp 140 Mbp1435 1305135 Mbp 134 Mbp2051 132 Mbp1629 649114 Mbp

71 X Chromosome 155 Million base pairs (bp) 1606 Genes Muscular Dystrophy Adrenoleukodystrophy Hemophilia A Hemophilia B Green Color Blindness Red Color Blindness X-linked Traits

72 Y Chromosome 58 Million base pairs (bp) 344 Genes

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