What causes NTDs and who is at increased risk?
The majority of NTDs are the result of multifactorial inheritance, meaning the combined effect of genetic and environmental factors. Poverty, famine, wars, seasonal variations and dietary preferences have contributed to our recognition that poor quality diets are an important environmental contributor. One type of genetic factor that has been implicated in multifactorial NTDs is the genetic variants in enzymes used in the homocysteine metabolism cycle, e. g. 5 10 methylene tetrahydrofolate reductase (MTHFR). There are considerable population variations in the frequency of the enzyme variants, so their importance as a contributor differs among ethnic groups. In this situation, folic acid supplementation helps improve enzyme function. Most babies born with an NTD are born to couples with no specific pregnancy, health or genetic concerns. Family members with close relatives with an NTD are at increased risk for an NTD-affected pregnancy, and this risk is influenced by the population rate
