W6 Lec 2 - Epidemiology and aetiology of birth defects

Question 1

What is a congenital disorder or birth anomaly?

Answer 1

Is a structural or functional abnormality that is present at birth but which may manifest at any point during the lifetime of
the individual

Question 2

When is a congenital abnormality considered serious?

Answer 2

When it has the ability to cause disability or death

Question 3

The 3rd leading cause of neonatal mortality in South Africa

Answer 3

congenital defects

*cause 1 in 15 live births

Question 4

What are the 2 causes of birth defects?

Answer 4

• Pre-conception/genetic causes (cause 90% of congenital anomalies):
  -Chromosome abnormalities
  -Structural/numerical – 6%
  -Single gene defects AD/AR/XL – 7.5%
  -Multifactorial abnormalities
  Genes + Environment –
  20-30
• Post-conception/non-genetic (cause 5-10% of congenital anomalies):
  -Teratogenic exposures;
  Physical agents, chemical agents, maternal medical conditions, infectious agents
  -Uterine constraint/environment

Question 5

How has malaria, in malaria endemic areas led to prevalance of birth defects in those regions?

Answer 5

Residents from malaria prevalant areas develop recessive genes for sickle cell anemia, thalassemia,
and G6PD. These genes are passed on to children during reproduction.

Question 5

What 5 factors influence the prevalence of birth defects?

Answer 5

• Consanguineous marriage
• Parental age (maternal)
• Migration
• Urbanisation
• Malaria
• Poverty and national level of HC

Question 6

How marternal age influence the prevalance of congenital defects?

Answer 6

Women over age 35 have a higher risk of having babies with ‘trisomy associated/derived syndromes’ than younger women. eg; trisomy 21

Question 6

When do the Consanguineous marriages present/pose higher risk of congenital defects?

Answer 6

• The risk is mostly doubled for the first cousin’s union

Question 7

How does Poverty and national level of HC contribute to the prevalance of congenital defects?

Answer 7

Poverty and poor access to standard healthcare leads to:
- Micro and macro-nutrient deficiencies
- Increased burden of infectious disease
- Reduced access to vaccination
- Increased burden of alcoholism
- Less screening/preventative care

Question 8

Management of patients with congenital abnormality

Answer 8

Management must follow:
The Principle of ‘Care’

1. Make a diagnosis
   -Early recognition of the abnormality
   -Appropriate investigations
   -Appropriate referral
2. Offer the best possible
   treatment available
   Surgery
   -Palliative care
   -Remedial therapy
   -Access to social
   services
3. Provide Genetic
   Counselling
   -Provide information
   -Psychosocial support

Question 9

Prevention of birth defects

Answer 9

1. PRIMARY:
   -FAMILY PLANNING
   -OPTIMIZING MATERNAL
   DIET & HEALTH
   -HEALTH EDUCATION
   -DETECTION & TREATMENT OF
   MATERNAL
   INFECTION
   -VACCINATION
2. SECONDARY:
   -MEDICAL GENETIC SCREENING
   -PRENATAL DIAGNOSIS &
   SCREENING
3. TERTIARY:
   -SURGERY
   -REMEDIAL THERAPY/SCHOOLING
   -PALLIATIVE CARE
   -NEWBORN SCREENING

Question 10

What is epidemiologic transition?

Answer 10

Epidemiologic transition refers to the long-term shifts in the patterns of diseases and causes of death that occur as societies undergo social, economic, and demographic changes