Genetics & Syndromes Flashcards
(34 cards)
From which parent is the chromosomal error/deletion in Angelman Syndrome?
Mother - complete or partial absence of chromosome 15
What are the characteristics of Angelman Syndrome?
- Happy demeanour
- Fascination with water
- Intellectual disability
- Severe delay in speech
- Epilepsy
- Microcephaly
- Wide mouth + widely spaced teeth
- Ataxia
- ADHD
- Fair skin/features
What is the genetic error in Klinefelter Syndrome?
Males with an additional X chromosome i.e. XXY
What are the features of Klinefelter Syndrome?
- Tall stature
- Soft, youthful features
- Gynaecomastia
- Subfertility/infertility
- Small testicles
- Weak musculature
- Narrow shoulders/Wide hips
- Mild/subtle learning disability
- Reduced libido
- Small increased risk in breast cancer
What is the genetic error in Turner Syndrome?
Females with a single X chromosome. Random/spontaneous mutation
What are the features of Turner Syndrome?
- Webbed neck (due to cystic hygroma)
- Short stature
- Broad chest with widely spaced nipples
- Infertility
- Underdeveloped ovaries
- High arched palate
- Downward sloping eyes with ptosis
- Obesity
- Cubitus valgus (exaggerated angle of elbow away from body when arm is extended downwards)
What are the genetics of Down Syndrome?
Trisomy 21 - usually due to non-disjunction during maternal oogenesis
Incidence increases with maternal age
What are the clinical features of Down Syndrome?
- Hypotonia
- Small, low set ears
- Prominent epicanthic folds
- Flat occiput/short neck (brachycephaly)
- Protruding tongue
- Short, broad hands
- Single palmar crease
- Wide, saddle gap between 1st & 2nd toes
- Intellectual disability
What are the associated conditions of Down Syndrome?
- 40/50% have congenital heart disease (mostly AVSD, but also ASD, VSD & Tetrology of Fallot)
- Duodenal/anal atresia
- Developmental hip dysplasia
- Eczema
- Deafness (both conductive and sensorineural)
- Cataracts
- Leukaemia
- Acquired hypothyroidism
- Epilepsy
What are the genetics of Prader-Willi Syndrome?
Chromosomal deletion on the proximal arm of chromosome 15. Spontaneous mutation
What are the clinical features of Prader-Willi Syndrome?
- Constant, instatiable hunger that leads to obesity
- Hypotonia
- Mild/moderate learning disability
- Hypogonadism
- Fair, soft skin (prone to bruising)
- Narrow forehead
- Strabismus
- Thin upper lip
- Downturned mouth
What are the genetics of Noonan Syndrome?
Multiple genes contribute - inherited in an autosomal dominant fashion. Affects males and females.
What are the clinical features of Noonan Syndrome?
- Short stature
- Broad forehead
- Downward sloping eyes with ptosis
- Wide spaced eyes (hypertelorism)
- Low set ears
- Webbed neck
- Widely spaced nipples
- Prominent nasolabial folds
What are the associated conditions of Noonan Syndrome?
- Congenital heart disease (particularly pulmonary stenosis, hypertrophic cardiomyopathy and ASD)
- Cryptorchidism (undescended testes) leading to infertility (fertility unaffected in females)
- Learning difficulties
- Bleeding disorders
- Lymphoedema
- Increased risk of leukaemia and neuroblastoma
What are the associated conditions of Turner Syndrome?
- Aortic stenosis
- Coarctation of the aorta
- Bicuspid aortic valve (most common cardiac defect)
- Horseshoe kidney
- Delayed puberty
What are the genetics of Marfan Syndrome?
Autosomal dominant condition regarding the gene responsible for creating fibrillin. Fibrillin is a component of connective tissue.
What are the clinical features of Marfan Syndrome?
- Tall stature
- Long neck
- Long limbs
- Long fingers
- Hypermobility
- Pectus carinatum or pectus excavatum
- Downward sloping palpable fissures
What are the hypermobility tests used in Marfan Syndrome? (specifically for arachnodactyly or long fingers)
- Cross thumb over palm, does it extend beyond outer border of the hand?
- Wrap thumb and fingers around wrist, do they overlap?
What are the associated conditions of Marfan Syndrome?
- Lens dislocation in the eye
- Joint dislocations and pain due to hypermobility
- Scoliosis of the spine
- Pneumothorax
- Gastro-oesophageal reflux
- Mitral valve prolapse (with regurgitation)
- Aortic valve prolapse (with regurgitation)
- Aortic aneurysms
What are the genetics of Fragile X Syndrome?
Mutation in FMR1 gene on the X chromosome. X-linked but unclear if dominant or recessive. Males always affected. May be de novo.
What are the clinical features of Fragile X Syndrome?
- Intellectual disability
- Long, narrow face
- Large ears
- Large testicles after puberty
- Hypermobility
What are the associated conditions of Fragile X Syndrome?
- ADHD/Autism
- Seizures/Epilepsy
What is the pathophysiology of Foetal Alcohol Syndrome?
- Excessive alcohol consumption in early stages of pregnancy
- Developing foetal nervous system is sensitive to alcohol toxicity
What are the clinical features of Foetal Alcohol Syndrome?
- Low/flat nasal bridge
- Indistinct philtrum
- Flat midface
- Short nose
- Thin upper lip
- Small chin
- Microcephaly
- Restricted growth
- Developmental delay/learning difficulties
