Developmental Abnormalities

Question 1

Spina Bifida

Answer 1

Fusion of the spinal cord should be complete by week 4 but in spina bifida, the posterior neuropore doesn’t close properly.

Question 2

Cleft palate

Answer 2

A defect posterior to the incisive foramen. Failure of tissue migration to completey fill the midline grooves.

Question 3

Tetralogy of Fallot

Answer 3

Classically 4 defects= Pulmonary stenosis, thickening of right ventricle, ventricular septal defect and malpositioned aorta

Question 4

Atrial septal defect

Answer 4

caused by patent foramen ovale. Blood flows between both atria.

Question 5

Achondroplasia

Answer 5

conversion of cartilage to bone and lack of bone growth due to GoF mutation in FGFR3 – normal sized torso and short limbs

Question 6

Polydactyly

Answer 6

extra finger(s) or toe(s) - associated with ZPA and Shh

Question 7

What is given to prevent spina bifida?

Answer 7

folic acid 3 months before pregnancy

Question 8

What is a teratogen?

Answer 8

any agent that can disturb the development of an embryo or fetus

Question 9

Give some examples of chemical teratogens and their effects

Answer 9

Thalidomide - Limb defects, heart malformations

Lithium - Heart malformations

Amphetamines - Cleft lip and palate, heart defects

Cocaine - Growth restriction, microcephaly, behavioral abnormalities

Alcohol - Fetal alcohol syndrome, maxillary hypoplasia, heart defects

Question 10

What is the classic triad for congenital rubella syndrome?

Answer 10

• sensorineural deafness
• eye abnormalities
• congenital heart disease

Question 11

name 3 causes of fetal growth restriction

Answer 11

Maternal- anaemia, smoking, Diabetes, age under 16

Foetal- inborn errors of metabolism, multiple pregnancy

Placental- impaired trophoblast invasion