A 30 year old woman is pregnant with her third baby. She consults her GP, who prescribes folic acid tablets to take for the duration of her pregnancy. The patient is curious about the reason for this.

Which of the following developmental defects are most likely to be caused by folic acid deficiency?

Options:
explanation: Folic acid deficiency is associated with an increased risk of neural tube defects in the developing foetus. Spina bifida is a specific form of neural tube defect, characterised by failure of the caudal end of the neural tube to close. By contrast, an atrial septal defect is a form of congenital heart malformation in which there is a hole in the septum between the two atria. Although research has shown some association of congenital heart defects with folic acid levels, it is not as closely linked as neural tube defects. This is therefore not the single best answer.
name: Atrial septal defect
label: d
answer: no
explanation: Folic acid deficiency is associated with an increased risk of neural tube defects in the developing foetus. Spina bifida is a specific form of neural tube defect, characterised by failure of the caudal end of the neural tube to close. By contrast, an extra copy of chromosome 21 leads to Down syndrome, which is associated with intellectual and developmental delays and characteristic facial features. Folic acid intake does not affect the development of this condition.
name: Presence of an extra copy of chromosome 21
label: b
answer: no
explanation: Folic acid deficiency is associated with an increased risk of neural tube defects in the developing foetus. Spina bifida is a specific form of neural tube defect, characterised by failure of the caudal end of the neural tube to close. By contrast, Fragile X Syndrome is a genetic disorder caused by an expansion of the CGG trinucleotide repeat in the FMR1 gene on the X chromosome. It is not thought to be caused by folic acid deficiency.
name: Excess cerebrospinal fluid in the brain
label: e
answer: no
explanation: Folic acid deficiency is associated with an increased risk of neural tube defects in the developing foetus. Spina bifida is a specific form of neural tube defect, characterised by failure of the caudal end of the neural tube to close. By contrast, a ventricular septal defect is a form of congenital heart malformation in which there is a hole in the septum between the two ventricles. Although research has shown some association of congenital heart defects with folic acid levels, it is not as closely linked as neural tube defects. This is therefore not the single best answer.
name: Ventricular septal defect
label: c
answer: no
explanation: This is the correct answer. Folic acid deficiency is associated with an increased risk of neural tube defects in the developing foetus. The neural tube is the embryonic structure that eventually gives rise to the brain and spinal cord. Spina bifida is a specific form of neural tube defect, characterised by failure of the caudal end of the neural tube to close, meaning the spinal cord and vertebrae do not fully develop, resulting in an exposed or open area of the spinal cord. This incomplete closure of the caudal end of the neural tube typically occurs within the first few weeks of pregnancy.
name: Failure of the caudal end of the neural tube to close
label: a
answer: yes

Correct answer: a