Paediatric Genetics Flashcards
What can multiple congenital anomalies occur due to?
Multiple congenital anomaly syndromes can occur:
- Single gene disorders 30%
- Chromosomal 10%
- Teratogens 5%
- Unknown 55%
These individually are rare, but common as a group
What is a syndrome?
Syndrome = pattern of clinical features occurring together
Multiple congenital anamaly syndromes - epidemiology
(prevalence of births)
- 3% of all births
How many genes are there?
22,000
What is the diagnosis of rare genetic conditions done by?
- History
- Description
- Recognition of patterns
- Testing
- Standard
- Biochemical, chromosome structure (microarray standard)
- Targeted testing
- Moving to trio-based exome/genome
- Standard
How do you describe a dysmorphic child?
- Position and shape of facial features
- Head – shape, size (macrocephaly, microcephaly), ear position (low set, posteriorly rotated)
- Eyes – hypertelorism (eyes distant from each other), telecanthus/epicanthic folds
- Hands (examples down syndrome, marfan syndrome)
- Finger length
- Digital abnormalities
- Palmar creases
- Growth of child
- Growth features
What is the medical term for eyes distant from each other?
Hypertelorism
What is a malformation?
Can occur alone or part of a syndrome
Examples:
- Polysyndactylty alone
- Hox D13 one cause
- Or acrocephalopolysyndatyly
- Greig/GLI3
What are examples of malformation?
- Polysyndactylty alone
- Hox D13 one cause
- Or acrocephalopolysyndatyly
- Greig/GLI3
What is a sequence?
Is where one abnormality leads to another, can have multiple causes
Examples:
- Pierre-Robin sequence
- Small chin to cleft palate
- Fetal akinesia sequence
- Reduced fetal movement
- Reduced breathing
- Contractures
- Clefting
- Lung hypoplasia
What are examples of sequences?
- Pierre-Robin sequence
- Small chin to cleft palate
- Fetal akinesia sequence
- Reduced fetal movement
- Reduced breathing
- Contractures
- Clefting
- Lung hypoplasia
What is deformation and disruption?
Pattern of development normal to start with but becomes abnormal
What is the meaning of:
- deformation
- disruption
Deformation = organ parts there
Disruption = parts of organ/body missing
What is an example of a deformation and disruption?
- Amniotic bands
What is an association?
Two features or more occur together more often than expected by change through an unclear mechanism
Examples are VATER:
- Vertebral anomalies
- Ano-rectal atresia
- Tracheo-oesophageal fistula
- Radial anomalies