Autosomal Aneuplodies ✅ Flashcards
What is true of most autosomal aneuploidies?
They are fatal in utero
Which autosomal aneuploidies are survivable to term?
- Trisomy 13
- Trisomy 18
- Trisomy 21
What autosomal aneuploidy has the most favourable outcome?
21 (Down’s syndrome)
Why does trisomy 21 have the most favourable outcome?
Because chromosome 21 has fewer genes than other chromosomes
Why does chromosome 21 have fewer genes than other chromosomes?
It is short and has low gene density
What is trisomy 13 known as?
Patau syndrome
What % of babies with Patau syndrome die in the first month?
50%
What is the prognosis of babies that survive the first month with Patau syndrome?
Most die in the first year
What are the common features of Patau syndrome?
- Polydactyly
- Cardiac abnormalities
- Midline abnormalities of the head and face
What midline abnormalities of the head and face are common in Patau syndrome?
- Closely-spaced eyes, single central eye (cyclopia)
- Midline cleft lip and palate
- Holoprosencephaly
What is holoprosencephaly?
When brain does not divide properly into left and right hemispheres
What happens to most babies with Edwards syndrome?
They die within the first year of life
What happens to children who survive the first year of life with Edwards syndrome?
They make little developmental progress
What are the features of Edwards syndrome?
- Dysmorphic features
- Poor growth antenatally and postnatally
- Small head
- Cardiac and renal abnormalities
Describe the dysmorphic features of Edwards syndrome?
They may be subtle, and can include;
- Ear anomalies
- Clinodactyly
- Overlapping fingers
- Micrognathia
- Rocker-bottom feet