Congenital abnormality and teratology Flashcards
Congenital anomaly
Abnormality of structure, function or disorder of metabolism that is present at birth and results in physical or mental disability
Teratology
Study of causes and biological processes leading to abnormal development at fundamental and clinical level, and appropriate measures for prevention
Most common, severe congenital anomalies
Heart defects
Neural tube defects
Down syndrome
Risk factors of congenital anomalies
Genetic- inherited vs sporadic mutation
Infectious- rubella, syphillis, zika
Teratogens
Socio-economic/ demographics- nutritional, environment, age
Prevention of congenital anomalies
Vaccination
Adequate intake of folic acid or iodine through fortification of staple foods or supplementation
Appropriate antenatal care
Genetic/ chromosomal abnormalities
Consanguinity increases the prevalence of rare genetic congenital anomalies
Some ethnic communities have a comparatively high prevalence of rare genetic mutations such as cystic fibrosis and haemophilia C
Screening for genetic disorders
In high risk patients e.g. those with previous recurrent pregnancy loss, or family history for a particular problem
In all patients through the UK AN screening program
Malformation
Flawed development of a structure or organ
Disruption
Alteration of an already formed organ
Deformation
Alteration in structure caused by extrinsic pressures
Dysplasia
Abnormal organisation of cells or tissues
Syndrome
Multiple congenital abnormalities
Group of abnormalities due to a single aetiology
e.g. single chromosomal/ gene problem
Sequence
Multiple congenital abnormalities but as a consequence of one abnormality
Potters sequence
Renal agenesis leading to oligohydramnios leading to skeletal deformities
Examples of chromosomal abnormalities
Down’s- trisomy 21
Edward’s- trisomy 18
Patau;s- trisomy 13
Turner’s- XO
Klinefelters- XXY
Down’s syndrome
Facial features
- small nose and flat nasal bridge/ flat face
- large tongue that may stick out of mouth
- eyes that slant upwards and outwards
- a flat back of the head/ thickened skin
Other external features
- broad hands with short fingers
- single palmar crease
- below average weight and length at birth
Edward’s syndrome T18
Facial abnormalities: small, abnormally shaped head, small jaw and mouth, low set ears, cleft lip/ palate
Skeletal abnormalities: long fingers that overlap, underdeveloped thumbs and clenched fists
Congenital heart defects: >90%
GI abnormalities: omphalocele, oesophageal atresia, tracheo-oesophageal fistula, umbilical or inguinal hernia, pyloric stenosis
Urogenital abnormalities: gonadal dysgenesis, horseshoe kidney, hydronephrosis, cystic kidneys, renal agenesis
Neurological problems: anencephaly, hydrocephaly, severe learning disability, seizures
Pulmonary hypoplasia
Patau’s syndrome
Congenital heart defects: >80%
Facial abnormalities: cleft lip/ palate abnormally small eye or eyes or absence of 1 or both eyes, reduced distance between the eyes, microcephaly
GI abnormalities: omphalocele, exomphalos
CNS disorder: holoprosencephaly (single brain)
Abnormally small penis in boys, enlarged clitoris in girls
Skeletal: extra fingers or toes, rounded bottom feet
Teratogens
An agent, such as a virus, a drug, or radiation, that causes malformation of an embryo or fetus
Warfarin effects
Chondrodysplasia
Microcephaly
Thalidomide effects
Limb defects/ heart defects
Rubella effects
Rubella (deafness)
Pesticides effects
Neural tube defects
Hyperthermia effects
Fetal death
Neural tube defects
Radiation effects
Microcephaly
Spina bifida
Alcohol effects
FAS (maxillary hypopalsia, mental retardation)
Androgen effects
Masculinisation of external genitalia
Features of fetal alcohol syndrome
Epicanthal folds
Flat nasal bridge
Small palpebral fissures
Railroad track ears
Smooth philtrum
Thin upper lip
Detecting congenital abnormalities
61% detected antenatally
8% at birth
6% at 2-4 weeks
18% after first month
