Aetiology & Prevention Flashcards
General
Specific cause can be identified in 80% of severe cases and 50% of mild cases
Can be broadly divided into genetic + environmental factors or timing of causative agent
Timing
50-70% prenatal factor (during embryogenesis)
10-20% perinatal factor (around the time of delivery)
5-10% postnatal factor (during first years of life)
Genetic factors
Autosomal chromosomal disorders e.g. Down
Sex chromosome disorders
Deletions & duplications
Autosomal recessive & dominant disorders
X-linked recessive & dominant disorders
Polygenic conditions
Mitochondrial & metabolic disorders
External prenatal factors
Infections e.g. rubella, CMV, syphilis, toxoplasmosis, HSV, HIV
Exposure to medication, drugs, alcohol, toxins
Maternal illness (diabetes, HTN, hypothyroidism, hypoparathyroidism, malnutrition)
Perinatal factors
Prematurity & low birth weight
Infections e.g. meningitis, encephalitis, neonatal septicaemia, pneumonia
Problems around the time of delivery (birth asphyxia, ICH, birth injury)
Newborn complications ( resp distress, hyperbilirubinaemia, hypoglycaemia)
Postnatal factors
CNS infection
Intracranial tumours
Hypoxic brain injury
Head injury
Toxic agents
Psychosocial environment
Subcultural ID
Concept of psychosocial causation controversial
Mild / borderline ID more common in lower SES
Best viewed as a cultural norm; generally no or minor impairments in adaptive functioning, dysmorphic characteristics less common, other disabilities unusual
Biological causation
Impairments more significant, no difference in SES, parents & siblings usually of normal intelligence, dysmorphic features more common
Primary prevention
Immunisation
Folic acid
Good medical follow up, investigation and intervention
Prevention of lead toxicity, iodine deficiency, foetal alcohol spectrum disorders, accidents
Secondary prevention
Screening & early treatment of congenital hypothyroidism + phenylketonuria
Planning or genetic counselling
Tertiary prevention
Medical, psychological, social support
Family support
Environmental adjustments & aids
Education
