L21 - Congenital abnormalities & teratology

Question 1

CLASSIFICATION

i) what is the WHO definition of congential abnormalities?
ii) are these physical or mental or both?
iii) what accounts for most of the deaths/morbidity/disability related to CAs?
iv) what are minor CAs?
v) what is the definition of a syndrome?

Answer 1

i) a wide range of abnormalities of body structure or function that are present at birth ie occur in utero
ii) both physical and mental
iii) structural abnormalities
iv) minor - struc changes that pose no significant health problem in the neonatal period and have limited consequences for the individual
v) syndrome - group of CA caused by a single aetiology

Question 2

DEFINITION OF STRUCTURAL ABNORMALITIES

i) define malformation & give eg
ii) define disruption & give eg
iii) define deformation - what is this similar to?
iv) define dysplasia
v) what are the two most common causes of neonatal death?

Answer 2

i) malformation = flawed development of a structure or organ
eg transposition of great arteries

ii) disruption = alteration of an already formed organ
- vascular event eg bowel atresia

iii) deformation = alteration in structure caused by extrinsic pressures
- mechanical eg talipes due to reduced amniotic fluid

iv) dysplasia = abnormal organisation of cells or tissues
v) most common cause of neonate death are cardiac abnormalities or chromosomal abnormalities

Question 3

CAUSES OF CONGENITAL ABNORMALITIES

i) name the three most common severe CAs
ii) name four factors that can contribute to the development of CAs
iii) name another factor related to parents that can increase genetic risk
iv) name three viruses that may cause CAs
v) give three ways to prevent CAs from occuring

Answer 3

i) heart defects, neural tube defects and downs syndrome
ii) genetics, infection, demographics and teratogens
iii) consanguinuety
iv) rubella, zika and syphillis
v) vaccination, folic acid/iodine for NT defects, appropriate antenatal care

Question 4

CHROMOSOMAL ABNORMALITIES

i) what increases the prevalence of inherited rare gentic abnormalities?
ii) which ethnic community has a high prevalence of genetic mutations
iii) when does a primary chromo abnormality occur? eg T21
iv) when may a woman be screened prenatally for genetic disorders? (2)

Answer 4

i) consanguineous parents
ii) ashekazi jews
iii) during development
iv) if shes had previous pregnancy loss or family history of a chromo problem

Question 5

DOWNS SYNDROME

i) give four facial features of a person with DS
ii) give two other external features that may be seen
iii) trisomy at which chromosome?
iv) give three other problems that may occur with DS

Answer 5

i) small nose/flat nasal bridge, large tongue, eyes that slant up and out, flat back of head
ii) broad hands with short fingers, single palmar crease, below avg weight and length at birth
iv) cardiac defects, duodenal atresia, learning disability

Question 6

EDWARDS SYNDROME

i) trisomy at which chromosome?
ii) name three facial abnormalities that may be seen? give two skeletal abnormalities
iii) what defect may 90% of patients have?
iv) give two GI and UG abnormalities
v) give two neuro problems
vi) what may be seen in the lungs?

Answer 6

i) T18

ii) facial - small abnormal shaped head, small jaw/mouth, low set ears, cleft lip or palate
skeletal - long fingers and undeveloped thumbs

iii) congenital heart defects

iv) GI - oes atreia, omphalocele
UG - gonadal dysgenesis, horseshoe kidney

v) ancephaly, hydrocephaly
vi) pulmonary hypoplasia

Question 7

PATAU SYNDROME

i) trisomy at which chromosome?
ii) what % have congential heart defects?
iii) give three facial abnormalities
iv) what may be seen in the CNS?
v) how may genitals appear?
vi) what is a characteristic feature in the feet
vii) how long do most survive?

Answer 7

i) T13
ii) >80%
iii) cleft lip, small eyes, absence of eyes
iv) holoprosencephaly (single brain hemi)
v) small penis in boys or enlarged clitoris in girls
vi) rocker bottom feet
vii) most die a few days after birth

Question 8

TERATOGENS

i) what is a teratogen? give three things that can act as teratogens
ii) give two examples of viruses that can act as a teratogen? what can this result in?
iii) when is an fetus most susceptible to damage by teratogens?
iv) give three drugs that can be teratogenic and what they cause

Answer 8

i) an agent that causes malformation of embryo/fetus
- virus, drug, radiation

ii) zika > microcephaly
rubella > deafness

iii) first 12 weeks (espec 3-8 weeks)

iv) warfarin > chrondodysplasia and microcephaly
thalidomide > limb/heart defects
sodium valproate > NT defects

Question 9

FETAL ALCOHOL SYNDROME

i) give four features of a classic picture of FAS
ii) are these babies big or small for gestational age?
iii) give two other features of FAS

Answer 9

i) flat nasal bridge, upturned nose, smooth philtrum, thin upper lip
ii) small for gestational age
iii) maxillary hypoplasia and mental retardation

Question 10

DETECTING CONGENITAL ABNORMALITIES

i) when are most detected?
ii) when are congenital heart abnorms often detected?
iii) which three things are screened for at 11+ weeks?
iv) name four things screen for in the 20 week scan
v) what three things are monitored in the third trimester?

Answer 10

i) during pregnancy
ii) 2-4 weeks postnatal
iii) ancephaly, major limb defects, DS
iv) heart, brain, skeletal, cleft lip/palate, movements (genetic muscle disorders)
v) growth, organs, amniotic volume, movement

Question 11

REASONS FOR DETECTION OF CAs

i) what may be offered if CAs are detected?
ii) give three conditions that may be treated in utero
iii) give two other reasons for why detection of CAs may be important

Answer 11

i) termination
ii) cleft palate, pulmonary shunts, transfusions
iii) time delivery correctly, refer to tertiary centre if needed, allow time for parents to accept/prepare