Down's Syndrome & Turner Syndrome Flashcards
What is Down’s syndrome caused by?
3 copies of chromsome 21 (trisomy 21)
What are the characteristic features of Down’s syndrome?
Face:
- upslanting palpebral fissures
- prominent epicanthic folds
- Brushfield spots in iris
- protruding tongue
- small low-set ears
- round/flat face
Flat occiput
Single palmar crease
Hypotonia (reduced muscle tone)
Congenital heart defects
Duodenal atresia
Hirschsprung’s disease
What are epicanthic folds?
Folds of skin covering the medial portion of the eye and eyelid.
What are the palpebral fissures?
Gaps between the lower and upper eyelid.
What is the key risk factor for Down’s syndrome?
Increasing maternal age
What is risk of Down’s syndrome in maternal age of ≥45 y/o?
1 in 50 or greater
What is risk of Down’s syndrome in maternal age of 20 y/o?
1 in 1500
What 3 mutations can cause Down’s syndrome?
1) Nondisjunction (94%)
2) Robertsonian translocation (5%)
3) Mosaicism (1%)
What is nondisjunction?
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.
What is Hirschsprung’s disease?
A birth defect in which some nerve cells are missing in the large intestine, so a child’s intestine can’t move stool and becomes blocked.
What cardiac complications may be associated with Down’s syndrome?
1) Endocardial cushion defect (AV septal canal defect)
2) VSD
3) Tetralogy of Fallot
4) Isolated patent ductus arteriosus
5) Secundum atrial septal defect
What is the most common cardiac complication of Down’s?
Endocardial cushion defect
How is fertility impacted in Down’s (in males vs females)?
Males - almost always infertile.
Females - usually subfertile, have an increased incidence of problems with pregnancy and labour.
Why are males almost always infertile in Down’s?
Due to impaired spermatogenesis
Give some later complications of Down’s
1) subfertility
2) learning difficulties
3) short stature
4) repeated respiratory infections (+hearing impairment from glue ear)
5) acute lymphoblastic leukaemia
6) hypothyroidism
7) Alzheimer’s disease
8) atlantoaxial instability
Individuals with Down’s syndrome are more likely to suffer from vision and hearing problems.
What is a very common condition resulting in hearing problems in people with Down’s?
Otitis media and glue ear
What are some visual complications seen in Down’s?
- refractive errors
- strabismus
- cataracts: congenital and acquired
- recurrent blepharitis
- glaucoma
What is the 1st line screening for Down’s?
When does this take place?
Combined test - done between 11 - 13+6 weeks
If women book later in pregnancy, what 2 tests may be offered for Down’s screening?
Triple or quadruple test