Genetic Presentations Flashcards
Outline the aetiology of Down Syndrome
Aetiology = trisomy 21
Mechanism = Mitotic nondisjunction (failure in mitosis for the two chromosomes separate)
How does down syndrome present?
LD
Flat face
Up slanting palpebral fissures
Epicanthal folds
Flat nasal bridge
Abundant neck skin
Small simple ears
Muscle hypotonia
Dysplastic pelvis
Protruding tongue
Single palmar crease
How is down syndrome screened for?
Combined test (11-13w) = NT +hCG + PAPP-A + womans age
How is down syndrome Mx?
Regular appts with paediatrician
SALT
Physio = help walking if they have low muscle tone
Optician or hearing specialist
OT = for help with their development
What conditions are associated with down syndrome?
ASD, VSD
Duodenal atresia
ToF
LD
Hypothyroidism
Outline the aetiology and pathophysiology of Turners syndrome
Partial or complete loss (monosomy) of the second sex chromosome
How does turners syndrome present?
- lymphoedema in the hands/feet
- aortic coarctation
- absent/horse shoe kidney
- widely spaced nipples, broad chest (shield)
- short stature
- webbed neck, thick neck
- low set ears
- ovarian dysgenesis (absent/incomplete puberty)
- amenorrhoea
- impaired growth
- CHD (coarctation)
- hypothyroidism
** normal intellectual function in most cases
How is turners syndrome Mx?
- recombinant growth hormone
- supplemental oestrogen
- surveillance of cardiac, renal, ENT, autoimmune probs
- psychological support
How is turners syndrome Dx?
Karyotyping
- amniocentesis
- postnatal blood tests
Outline foetal alcohol syndrome
Alcohol exposure during the mother’s pregnancy = interferes with the delivery of oxygen and optimal nutrition
S+S =
- small eyes, exceptionally thin upper lip, short upturned nose, no philtrum
- deformities of joints, limbs and fingers
- low physical growth before and after birth
- vision/hearing diff
- small head circumference and brain size
- heart defects
- problems with kidneys and bones
- cognition: poor memory, coordination, inattention, LD
There’s no cure or specific treatment for fetal alcohol syndrome
Outline Marfan’s syndrome
Autosomal dominant defect in gene FBN1, resulting in abnormal fibrillin-1 (CT)
S+S = abnormal facial appearance, nearsightedness, crowding of teeth, tall, thin body, abnormally shaped chest, long arms, legs, and fingers, laxity of joints, curved spine, flat feet, poor healing of wounds or scars on the skin ,dilation of the aortic root, mitral valve prolapse, emphysema, spontaneous pneumothoraces
Mx = based on what is effected
- Heart: bisoprolol
- Surgery: repair aorta, valves, heart replacement
Outline PKU
Inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine - low levels of the enzyme phenylalanine hydroxylase
Normally detected on newborn screening
S+S = LD, Without treatment intellectual disability, seizures, behavioral problems, mental disorders, musty smell
Mx = diet low in phenylalanine, protein supplements, enzyme substitute called pegvaliase which metabolizes phenylalanine
Outline the pathophysiology and aetiology of Duchenne Muscular Dystrophy
Mutation in the DMD gene changes the DMD RNA so that it no longer codes for functional dystrophin protein, muscle gets replaced by fibroadipose
More common in boys
X-linked recessive
How does Duchenne Muscular Dystrophy present?
- Progressive muscle weakness - legs/pelvis
- Frequent falls
- Difficulty rising from a lying or sitting up position
- Trouble running and jumping
- Waddling gait
- Walking on the toes
- Large calf muscles
- Muscle pain and stiffness
- LD
Gowers’ sign = indicates weakness of the proximal muscles
How should suspected Duchenne Muscular Dystrophy be investigated?
Bloods = CPK (creatine phosphokinase) markedly elevated
Electromyography
Genetic testing
Muscle biopsy
ECG, ECHO
Lung function testing
