Congenital Malformations + Teratology Flashcards
What are malformation abnormalities and what causes them?
- Occur during formation of structures
- Most originate 3-8th week of gestation
causes = environmental/genetic factors
What are disruption abnormalities?
- Alteration of pre-existing structures due to destructive processes
e. g. amniotic band syndrome/ limb amputations
What are deformation abnormalities?
- Mechanical factors which mould fatal parts over prolonged periods
e. g. clubfeet = from compression in amniotic cavity
What is Oligohydraminos?
- Type of sequence abnormality
- Deficiency of amniotic fluid
What are syndromes?
- Pattern of malformations occurring together, considered to have specific common cause
- Term indicates diagnosis made + risk of recurrence known
What are associated recognised patterns of malformation?
Where initiating cause has not been identified
What is teratology?
The study of abnormal development (prenatal)
What are teratogens?
Anything capable of disrupting embryonic or fatal development + producing malformations/birth defects
What are the 3 pain principles of teratogenesis?
- Dosage
- Time + length of exposure
- Genotype of embryo
What causes birth defects?
- Chromosomal abnormalities
- Single gene defects
- Enviro
- Multifactorial
- Unidentified
What are the types of chromosomal abnormalities?
Numerical or Structural
What percentage of conceptions end in spontaneous abortion?
50% -> 50% of these = due to chromosomal abnormalities
What are the most common chromosomal abnormalities?
- Monosomy (Turner syndrome)
- Triploidy
- Trisomy (21, 18, 13)
What causes chromosomal abnormalities?
Chromosome breakage =
- loss of broken piece
e. g. Cri dut Chat dyndrome - microdeletions
- fragile sites (regions of CGG repeats)
e. g. Fragile X syndrome
What is Cri dat Chat syndrome?
- Partial depletion of short arm of chromosome 5
- Children have catlike cry, microcephaly, mental retardation + congenital heart disease
