Genetics - Noonan and Marfan Syndrome Flashcards
How is Noonan syndrome inherited?
Autosomal dominant for the majority of cases
What are the features of Noonan syndrome?
Hypertelorism
Broad forehead
Short stature
Downward sloping eyes with ptosis
Prominent nasolabial folds
Low set ears
Webbed neck
Widely spaced nipples
What is hypertelorism?
Wide space between eyes
What conditions are associated with Noonan syndrome?
Congenital heart disease
Cryptorchidism
Learning disability
Bleeding disorders
Lymphoedema
What congenital heart conditions are associated with Noonan syndrome?
Pulmonary valve stenosis
Hypertrophic cardiomyopathy
ASD
What is cryptorchidism?
Undescended testes
Can lead to infertility
Fertility is normal in women
What cancers are people with Noonan syndrome most at risk of?
Leukaemia
Neuroblastoma
How is Noonan syndrome managed?
Supportive
MDT involvement
Main complication is congenital heart disease and management of that, corrective surgery
What is Marfan syndrome?
Autosomal dominant condition affecting FBN1 gene which is responsible for fibrillin
This causes abnormal connective tissue
What are the features of Marfan syndrome?
Tall
Long neck
Long limbs
Arachnodactyly
High arch palate
Hypermobility
Pectum carinatum or excavatum
Downward sloping palpable fissures
Aortic regurgitation murmur
What tests are used for arachnodactyly?
Ask patient to cross their thumb across palm
If thumb tip goes past opposite edge of hand this indicates arachnodactyly
Ask patient to wrap thumb and fingers of one hand around other wrist, if thumb and fingers overlap indicates arachnodactyly
What conditions are associated with Marfan syndrome?
Lens dislocation in the eye
Joint dislocations and pain due to hypermobility
Scoliosis
PTX
GORD
Mitral valve prolapse with regurgitation
Aortic valve prolapse with regurgitation
Aortic aneurysms
What is the greatest risk in Marfan syndrome?
Cardiac complications
Valve prolapse
Aortic aneurysms
How is Marfan syndrome managed?
Minimise blood pressure and heart rate to minimise stress on the heart and complication risk
- Lifestyle changes, avoid intense exercise
- Avoiding caffeine and stimulants
- Preventative medications e.g. beta blockers and angiotensin II receptor antagonists
- Physiotherapy
- Genetic counselling
What needs special consideration in Marfan syndrome?
Pregnant patients
Significant risk of aortic aneurysm formation and associated complications
