cancer genetics

• Health


  Complete physical, mental and social well-being
• Disease


  Malfunctioning of body or mind
• Etiology - types of causes


  • Environmental agents
  • Genetic factors
  • Immunological
  • Metabolic disorders
• Pathology


  Structural and functional abnormalities that are expressed as diseases of organs or systems
• Pathogenesis


  How the etiologic agents cause a disease, i.e. morphological and functional changes in the body mechanism
• Lesion


  Unit of abnormality, usually anatomical
• Symptoms


  What a patient complains: e.g. pain, anxiety, restlessness
• Signs


  What a doctor detects on examination: e.g. lump, irregular heart beat
• Inflammation


  Redness, swelling, heat, pain, loss of function
• Prognosis


  The prospect of recovery or survival from a disease
• Epidemiology


  Study of causes, distribution and control of a disease in a population
• Syndrome


  A disease characterised by multiple abnormalities e.g. Down's syndrome (mental and heart defects)
• Lesion


  Structural abnormality responsible/ results due to ill health e.g. rash, growth on skin
• Classification of diseases


  • Causative agent (e.g. infectious, genetic, nutritional)
  • Inflammatory/ degenerative/ neoplastic
  • Acute/chronic
  • System involved
  • Primary and secondary causes
  • Congenital/ acquired
  • Mild/moderate/severe
  • Benign/malignant
• Characteristics of a disease


  • Etiology (cause)
  • Pathogenesis (mechanism)
  • Manifestations (morphological, functional and clinical changes (sign and symptoms))
  • Complications (secondary effects)
  • Prognosis (outcome)
  • Diagnosis: signs and symptoms+lab investigation
• Pathogenesis of a disease

  1. Etiology (causation of disease)

  2. Pathogenesis

  3. Sign and symptoms

  4. Complications
• Prognosis


  How a patient is expected to do after a disease is diagnosed
• Reporting a disease - 3 rates


  • Prevalence rate
  • Incidence rate
  • Mortality rate
• Congenital causes of diseases - 2 types


  • Condition/trait present at birth
  • Non genetic causes
  • Genetic causes
• Non-genetic congenital causes of diseases - 2 types


  • TORCH (Toxoplasma, Others, Rubella virus, Cytomegalovirus, Herpes simplex virus)
  • Iatrogenic (e.g. fetal alcohol syndrome, thalidomide)
• Diseases caused by chromosomal abnormalities - 4 types


  • Deletion
  • Inversion
  • Translocation
  • Increased chromosome copy number
• Diseases due to mutations in genes - 3 types


  • Inherited defective genes (monogenic, polygenic)
  • Mitochondrial inheritance
  • Acquired defective gene (after birth)
• Sickle cell anaemia and cancer are mutation induced diseases
• Multifactorial/polygenic inheritance


  Inheritance pattern of a trait or condition that is influenced by multiple genes (polygenic) and environmental/lifestyle factors (multifactorial)
• Multifactorial/polygenic diseases


  • Diabetes
  • Hypertension
  • Asthma
  • Autoimmune diseases
• Mode of inheritance of genes


  • Allele (alternative form of a gene)
  • Homozygous (both genes are the same)
  • Heterozygous (both genes are different)
• Mode of inheritance of genetic diseases


  • Autosomal dominant
  • Autosomal recessive
  • X-linked recessive
• Diseases caused by abnormal sex chromosomal number


  • Turner syndrome
  • Klinefelter's syndrome
• Down syndrome


  Most common cause of intellectual disability (IQ 25-70, norm 90-110), caused by presence of an extra chromosome 21, with shortening of all body parts, wide flat face, small nose, congenital heart disease, increased risk of specific leukemia and immunological deficiencies
• Bacteria causing diseases


  • Gram-positive (exotoxin, e.g. Staphylococcus, Clostridium)
  • Gram-negative (endotoxin, e.g. Salmonella, E. coli)
• Viral Pathogenesis


  • Cytocidal and cytopathic
  • Immune lysis
  • Neoplastic transformation
  • Cell fusion