Predictive Medicine and Genetics

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Predictive Medicine and Genetics

• Dr. Laila Zahed
• Visiting Professor
• St.Georges Hospital - Beirut
• Balamand University

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Medicine

• Focus on illness
  
• Focus on risk of illness

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Predictive tests in single gene disorders

• High risk of developing a debilitating disorder
  (25-50)
• Prenatal diagnosis
• (e.g. Cystic Fibrosis)
• Neonatal screening (e.g. PKU)
• Adult diagnosis (e.g.Huntington disease)

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Treatment/Intervention

• Only available for a limited number of disorders
• - dietary intervention (PKU)
• - blood donation (Haemochromatosis)
• Most cases termination of pregnancy

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But

• Single gene disorders are rare (1-3 of disease
  burden)
• Concern a limited number of families
• Major causes of premature death and disability
  are NOT monogenic

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Multifactorial conditions

• 60 of adults

Diabetes
Cardiovascular disease
Behavioral disorders
Mental illness
Cancer
Hypertension
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Multifactorial disorders

• Genes
• 
  Environment

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Predictive Medicine

• Screening healthy people for gene variants that
  predict an increased risk of developing a serious
  illness later in life
• Aim permit monitoring, treatment or intervention
  in common multifactorial diseases
• Example diet, exercise or drug administration

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Current Examples

• Thrombophilia screening
• DVT
• Placental dysfunction
• Cerebral vein thrombosis

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How?

• Gene Chips

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Doctor-Patient Relationship and Ethics
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Doctor-Patient

• Prediction Prevention Treatment
• Advice on how to manage a susceptibility rather
  than looking for a treatment for a disorder
• Preventive medicine is mass medicine (e.g.
  vaccination) whereas predictive medicine is
  personalized medicine limited to individuals at
  risk

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Ethical issues

• 1. Predictions are statistical the risk, even in
  the presence of a mutation, is not 100
• e.g. BRCA1/2, 85 risk of developing the disease
• Only 5 of breast cancer patients have a mutation
  in these genes
• With polymorphisms, the association is even
  weaker, therefore interpretation can be harder

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Ethical issues

• 2. Therapy or prevention do not always exist in
  case of BRCA1/2 mutation
• - monitoring by regular mammography (exposure
  to X-ray)
• - prophylactic mastectomy (mutilation)

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Ethical issues

• 3. Effect on the life of the individual activism
  (taking control) vs. fatalism (abandoning to
  fate)
• Open future vs.
• inescapable fate

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Ethical issues

• 4. Consent and counseling
• - autonomy and freedom right to know, not to
  know or refuse to know
• - non-directive counseling pre and post-testing
• - conflict of interest towards other individuals
  from the same family

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Ethical issues

• 5. Confidentiality
• - risk of discrimination and segregation
• - access of insurers and employers to
• genetic risk information
• - accessibility to medical services

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DNA Art