Genetics Flashcards
Are there any risk factors for having a baby with Down syndrome?
Advancing maternal age:
- At 20, the risk of having a baby with Down syndrome is around 1/1500
- At 40, the risk is around 1/100
List the characteristic dysmorphic features of an individual with Down syndrome
- Round face and flat nasal bridge
- Small ears
- Single palmar crease
- ‘Sandal’ gap (wide gap between first and second toes)
Give some examples of complications of Down syndrome
- Intellectual disability
- Developmental delay
- Visual and/or hearing impairments
- Congenital heart disease, e.g. septal defects
- Gastrointestinal abnormalities, e.g. duodenal atresia
- Sterility in males
- Increased risk of certain cancers, e.g. ALL
- Increased risk of early-onset Alzheimer’s
Edwards syndrome is also known as…
Trisomy 18
List the characteristic dysmorphic features of an individual with Edwards syndrome
- Micrognathia (small jaw)
- Low set ears
- Overlapping fingers
- ‘Rocker-bottom’ feet
Patau syndrome is also known as…
Trisomy 13
List the characteristic dysmorphic features of a baby with Patau syndrome
- Microcephaly
- Microphthlamia (and in some cases, cyclopia)
- Polydactyly
What is Turner syndrome?
- Chromosomal disorder affecting females, where one of the X chromosomes is completely or partially absent
- Can be abbreviated as 45, X
What are the clinical features of Turner syndrome?
- Short stature
- Neck webbing
- Primary amenorrhoea
What are the potential complications of Turner syndrome?
- Fertility problems
- Congenital heart defects, e.g. bicuspid aortic valve, coarctation of the aorta
- Renal malformations, e.g. horseshoe kidney
- Increased risk of T2DM and hypothyroidism
Describe the management of Turner syndrome
- Growth hormone replacement therapy in childhood
- Sex hormone replacement therapy to promote development of secondary sexual characteristics
- IVF can make pregnancy possible for some women
What is Klinefelter syndrome?
- Chromosomal disorder affecting males, where they inherit an extra X chromosome
- Can be abbreviated as 47, XXY
What are the clinical features of Klinefelter syndrome?
- Infertility (most common presentation) and small testes
- Gynaecomastia
- Less muscle mass
- Less pubic/facial hair
Describe the management of Klinefelter syndrome
- Hormone replacement therapy
- Fertility treatment
What causes Fragile X syndrome?
- Trinucleotide repeat expansion mutation
- X linked inheritance (affects males)
