Current therapy of genetic disorders
Download
1 / 38

Current Therapy of Genetic Disorders - PowerPoint PPT Presentation


  • 188 Views
  • Updated On :

Current Therapy of Genetic Disorders. Preventive Metabolic Manipulation Gene Product Replacement Cell or Organ Transplantation Gene Therapy. Therapy of Genetic Disorders. Preventive Therapy Prenatal diagnosis Preimplantation diagnosis (in vitro fertilization, testing of embryo &

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Current Therapy of Genetic Disorders' - kura


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Current therapy of genetic disorders l.jpg
Current Therapy of Genetic Disorders

  • Preventive

  • Metabolic Manipulation

  • Gene Product Replacement

  • Cell or Organ Transplantation

  • Gene Therapy


Therapy of genetic disorders l.jpg
Therapy of Genetic Disorders

  • Preventive Therapy

    • Prenatal diagnosis

    • Preimplantation diagnosis

      (in vitro fertilization, testing of embryo &

      implantation of normal embryo)

    • Preventive screening for disease onset


Therapy of genetic disorders3 l.jpg
Therapy of Genetic Disorders

  • Metabolic Manipulation

    • Dietary restriction

      • (Lactose restriction for Lactase deficiency; phenylalanine restriction for phenylketonuria)

    • Dietary Supplementation

      • (Vitamin C for Scurvy, Biotin for Biotinidase deficiency, Starch for G-6-P deficiency)

    • Chelation and enhanced excretion

      • (copper chelation for Wilson Disease)

    • Metabolic inhibitors

      • (allopurinol for gout, Statins for hypercholesterolemia,)


Slide4 l.jpg
Lactase deficiency: Dietary Restriction: lactose free (dairy products)Dietary supplementation: lactase pills

  • All other mammals and most people lose the ability to digest lactose by adulthood

  • Lactase persistence is found in 50-90% of Europeans but is much rarer in other populations

  • Lactase persistence is associated with two single nucleotide polymorphisms (SNPs) 5’ of LCT

    • -13910 C/T, -22018 G/A


Lactase has been under very strong selection l.jpg

+

????

Lactase has been under very strong selection

Persistent LCT

Perhaps?

Estimated age of lactase persistence haplotype 180 generations

(3,600 years)

Dairy farming: 5,000-9,000 years ago

Courtesy JN Hirschhorn Harvard


Evolutionary cure of lactase deficiency l.jpg
?Evolutionary cure of lactase deficiency

  • Genetic signatures of recent positive selection can be found

  • LCT (lactase) shows remarkably strong evidence of recent positive selection

  • New metrics may locate other regions of the genome that have been under recent positive selection

Courtesy JN Hirschhorn Harvard


Slide7 l.jpg


Slide8 l.jpg

Dietary Supplementation for Biotinidase deficiency: persistence of lactase in Africa in different dairy farming regions

Biotin Cycle


Slide9 l.jpg

Symptom persistence of lactase in Africa in different dairy farming regions

>50%

Alopecia (hair loss) Developmental delay Hypotonia (poor muscle tone)Ketolactic aciduriaSeizuresSkin rash/skin infection

25-50%

Ataxia (poor coordination)Conjunctivitis (redness of the eye)Hearing lossLethargy (drowsiness)Mild hyperammonemiaBreathing problemsEye problems

10-25%

Coma Feeding difficulties/vomiting/diarrhea Fungal infections

<10%

Hepatomegaly (enlarged liver)Speech problems Splenomegaly (enlarged spleen)


Slide10 l.jpg

After Biotin treatment persistence of lactase in Africa in different dairy farming regions

Before Biotin treatment

Effects of Dietary SupplementationTherapy

with Oral Pharmacologic Doses of Biotin


Therapy of genetic disorders11 l.jpg
Therapy of Genetic Disorders persistence of lactase in Africa in different dairy farming regions

  • Gene Product Therapy

    • Hormone, protein or enzyme replacement

      • Hormone supplementation:

        • Hypothyroidism: thyroid

        • Congenital adrenal hyperplasia: cortisol

        • Growth hormone

      • Hemophilia; clotting factors

      • Diabetes: insulin

      • Enzyme replacement

        • Beta glucosidase : Gauchers

        • Alpha glucosidase: Pompe

        • Adenosine deaminase (PEG): ADA- SCID


Slide12 l.jpg

Enzyme Replacement Therapy of Inherited Disorders persistence of lactase in Africa in different dairy farming regions

  • Extension of paradigm of therapy for deficiency of

  • plasma proteins (eg hormones & clotting factors)

  • May not require targeting intracellularly if stored

or toxic metabolite is in equilibrium with plasma

  • Targeting of deficient protein into cells and

  • organelles would provide the widest application


Examples of current enzyme therapy l.jpg
Examples of Current Enzyme Therapy persistence of lactase in Africa in different dairy farming regions

  • Current FDA approved enzyme replacement therapy

    • Adenosine deaminase deficiency (SCID)-

      • Severe combined Immunodeficiency

      • No targeting to cells, but removal of metabolites from plasma

    • Several Lysosomal Storage Disorders

      • Genetic deficiency of Lysosomal Enzymes

      • Therapy: Targeting of deficient enzyme to lysosomes


Slide14 l.jpg

dATP persistence of lactase in Africa in different dairy farming regions

dATP nl

Adenosine deaminase deficiency: cellular & metabolic interactions

other cells

lymphoid cells & RBCs

deoxyadenosine


Slide15 l.jpg

dATP persistence of lactase in Africa in different dairy farming regions

Adenosine deaminase deficiency: cellular & metabolic interactions:

Effect of enzyme therapy

lymphoid cells & RBCs

deoxyadenosine

Injection of PEG Calf

Adenosine Deaminase

deoxyinosine


Lysosomal storage diseases l.jpg
Lysosomal Storage Diseases persistence of lactase in Africa in different dairy farming regions

  • Lysosomes: intracellular organelles containing hydrolytic enzymes that degrade macromolecules (recycling and “garbage disposal” for cells)

  • Lysosomal enzymes are targeted to lysosomes by interaction with Mannose 6 PO4 receptorsin the cell

  • Lysosomal enzymes can be taken up into the cell from plasma by interaction with Mannose 6 PO4 receptors on cell surface


Slide17 l.jpg

ENZYME REPLACEMENT THERAPY persistence of lactase in Africa in different dairy farming regions

FOR LYSOSOMAL STORAGE DISEASES

Disease Current Status

  • Gaucher Disease Approved 1991

  • Fabry Disease Approved 2001/03

  • Mucopolysaccharidosis I Approved 2003

  • Mucopolysaccharidosis VI Approved 2005

  • Mucopolysaccharidosis II Approved 2006

  • Pompe Disease Approved 2006

  • Niemann-Pick B Disease Phase 1 Trial


Therapy of genetic disorders18 l.jpg

Cells persistence of lactase in Africa in different dairy farming regions

Bone marrow Immunodeficiency Disorders

Organs

Kidney Fabry Disease

Liver Tyrosinemia

Therapy of Genetic Disorders

  • Cell or Organ Transplantation


Gene therapy types l.jpg
Gene Therapy: Types persistence of lactase in Africa in different dairy farming regions

  • Introduction of normal gene

    • Somatic

    • Germ line

  • Therapy of noninherited disorders

    • (cancer, AIDS)

  • Production of gene product for administration

    • (hemophilia, growth hormone, erythropoietin)


Somatic gene therapy l.jpg
Somatic Gene Therapy persistence of lactase in Africa in different dairy farming regions

Introduction of recombinant genes into somatic cells to treat genetic or acquired disease

  • Does not involve germ line

  • applicable to any disease with known molecular basis of pathogenesis

  • currently does not involve removal, repair or site-specific replacement of mutant genes

  • may not require permanent alteration of cells (repetitive therapy)


Disease characteristics currently ideal for gene therapy l.jpg
Disease Characteristics Currently Ideal for Gene Therapy persistence of lactase in Africa in different dairy farming regions

  • Lethal disorder

  • Course not highly variable

  • Reversible

  • No universal therapy

  • Gene cloned

  • No tissue specificity or regulation

  • Bone marrow cells involved


State of the art of genetic engineering l.jpg
State of the Art of Genetic Engineering persistence of lactase in Africa in different dairy farming regions

  • Ideal

    • Replace defective gene with normal (site specific insertion)

    • Target vector containing the gene to damaged cell

    • In vivo administration safe, effective and permanent (integration into DNA but not at oncogenic sites)

    • Vector contains all regulatory elements

  • Current

    • Site specific insertion very early and experimental

    • No current trial incorporates all of the ideal requirements


Gene therapy potential successes l.jpg
Gene Therapy Potential Successes persistence of lactase in Africa in different dairy farming regions

Disease Cell/tissue Vector

X-linked & ADA- Stem Cell Retrovirus

Severe Combined (bone marrow)

Immunodeficiency


Slide24 l.jpg

Reversion of mutation persistence of lactase in Africa in different dairy farming regions

to normal

Normal cells

Mutant cells

Somatic Mosaicism:

Reversion of an Inherited Mutation

to Normal and Selective Growth Advantage

Mutant


Successful gene therapy for immunodeficiency diseases 2005 l.jpg
“Successful” Gene Therapy for Immunodeficiency Diseases:2005

  • Retroviral vector used despite major disadvantages

  • Over 14 patients with X linked severe combined immunodeficiency of 3 different types have been treated successfully

  • Oncogenic insertion in two of 14 children-leukemia

  • - X-linked SCID trials suspended but now reinstituted

  • ~8 patients with ADA deficiency treated


Current therapy of genetic disorders26 l.jpg
Current Therapy of Genetic Disorders Diseases:2005

  • Preventive

  • Metabolic Manipulation

  • Gene Product Replacement

  • Cell or Organ Replacement

  • Gene Therapy


Slide27 l.jpg

Current Therapy of Genetic Disorders Diseases:2005

  • Experimental

  • Gene Therapy (Experimental)

  • Correction with oligonucleotide or RNAi

  • Silencing (RNAi and others)

  • Transplicing

  • “Read through” of nonsense mutations


Ideal viral vectors l.jpg
Ideal Viral Vectors Diseases:2005

  • Replication defective

  • Accommodates large inserts

  • High titer with broad cell range

  • High level of expression of inserted gene

  • Unique promotors

    • Tissue specific vs universal

    • On/off switch; controllable expression

  • Non-toxic


Slide30 l.jpg

Current Enzyme Therapy of Diseases:2005 Lysosomal Disorders with Intracellular Replacement of Enzyme:

Currently “standard of care”

Gauchers Disease (beta glucosidase; non neuronopathic)

Current Clinical Trials:

Glycogen Storage Disease Type II (acid maltase)

Fabry Disease (alpha galactosidase)

Hurler Disease (alpha iduronidase)

Hunter Disease (iduronate sulfatase)


Slide31 l.jpg

Lysosomes Diseases:2005


Slide32 l.jpg

Lysosomal enzymes contain a recognition site for targeted uptake into cells and lysosomes

  • enzyme protein synthesized in endoplasmic reticulum

  • carbohydrate (high mannose) added in ER

  • mannose 6 phosphate added in Golgi:

  • some enzyme secreted to outside of cell

  • mannose 6 phosphate binds to receptors, leading to

  • targeting to lysosomes and uptake of enzyme into cells


Enzyme replacement therapy for lysosomal disorders l.jpg
Enzyme Replacement Therapy for Lysosomal Disorders targeted uptake into cells and lysosomes

  • Requirements

    • Unprocessed enzyme that will be taken up by cells and targeted to lysosomes

  • Solutions

    • Purify from cultured cells

      • (introduce gene into cells, amplify copy number, mass culture, purify protein) Currently FDA approved approach

    • Purify from milk of an animal

      • (attach casein promotor to gene, introduce into ovum (transgenic), select animal(s) producing greatest amount of enzyme, purify enzyme from milk) Attractive but problems and difficult to get approval


Considerations for gene therapy l.jpg
Considerations for Gene Therapy targeted uptake into cells and lysosomes

  • State of the art of genetic engineering

  • State of the art of manipulation of cells and organs

  • Disease characteristics


Variables in current gene therapy trials l.jpg
Variables in Current Gene Therapy Trials targeted uptake into cells and lysosomes

  • Vector for delivery of gene

  • Ex vivo vs In vivo administration

  • Permanent integration into DNA vs transient expression

  • Incorporation of regulatory elements


Slide36 l.jpg

Examples of Current Enzyme Therapy targeted uptake into cells and lysosomes

  • Current FDA approved enzyme replacement therapy

    • Adenosine deaminase deficiency (SCID)-

      • Severe combined Immunodeficiency

      • No targeting to cells, but removal of metabolites from plasma

    • Gaucher Disease (Beta glucosidase deficiency)

      • Gaucher Disease (non-neuronal only)

      • Lysosomal Storage Disorder

      • Targeting of deficient enzyme to lysosomes


Types of somatic gene transfer l.jpg
Types of Somatic Gene Transfer targeted uptake into cells and lysosomes

  • Ex vivo

    • Gene or expression vector carrying the gene is inserted into explanted or cultured cells which are then transplanted into the patient

  • In vivo

    • Gene or expression vector carrying the gene is administered directly to the patient


Slide38 l.jpg

ENZYME REPLACEMENT THERAPY targeted uptake into cells and lysosomes

FOR LYSOSOMAL STORAGE DISEASES

Gaucher Disease Approved 1991

Fabry Disease Approved 2001 (EU), 2003 (US)

Mucopolysaccharidosis I Approved 2003 (EU & US)

Mucopolysaccharidosis VI Approved, 2005 (US& EU)

Mucopolysaccharidosis II Approved, 2006 (US)

Pompe Disease (AMD) Approved, 2006 (US & EU)

Niemann-Pick B Disease Phase 1 Trial Underway


ad