Congenital Disorders Flashcards
What disease is also known as ‘brittle bone disease’?
Osteogenesis imperfecta
Where is the defect in osteogenesis imperfecta?
The synthesis or organisation of type I collagen which accounts for most of the composition of bone
The majority of cases of osteogenesis imperfecta are inherited how? What does this mean?
Majority are autosomal dominant, usually this means they are milder cases
What are some features of autosomal dominant inherited osteogenesis imperfecta?
Short stature with multiple deformities and fragility fractures, blue sclera and hearing loss
Rare cases of osteogenesis tend to be more severe and are inherited how?
Autosomal recessive
Give some features of autosomal recessive osteogenesis imperfecta?
Severe scoliosis and deformity, may be fatal in the perinatal period
Osteogenesis imperfecta results in low energy fractures. What are some other causes of this which should be considered if a child has this presentation?
NAI or osteopenia (associated with prematurity)
Most adults with osteogenesis imperfecta will have what?
Scoliosis
The commonest form of skeletal dysplasia is what? How is this usually inherited?
Achondroplasia: can be autosomal dominant but >80% of cases are sporadic
Describe achondroplasia?
Disproportionately short limbs, with a prominent forehead and wide nose. Joints are lax. Mental development is normal.
How may very mild cases of osteogenesis imperfecta present?
With relatively normal x-rays but a history of low impact fractures
What are the bones like in osteogenesis imperfecta? How do fractures heal?
The bones are very thin, gracile and osteopenic. Fractures heal with abundant callus.
How are fractures related to osteogenesis imperfecta usually treated?
Splintage, traction or surgical stabilisation
In severe cases, osteogenesis imperfecta can cause bowing of the bones which leads to stress fractures. How are these treated?
May need osteotomies and intra-medullary stabilisation
What are skeletal dysplasias?
A group of genetic disorders (hereditary or sporadic) which lead to short stature which can be proportionate or disproportionate
How does skeletal dysplasia cause a short stature?
Abnormal development of bone and connective tissue
As well as short stature, what are some features of skeletal dysplasia that may or may not always be present?
Learning difficulties, deformities, hyper mobility, skin abnormalities, tumour formation, intrauterine/premature death
What type of tumour is associated with skeletal dysplasia?
Haemangioma
Treatment for skeletal dysplasia is supportive. Give some examples of this?
Preventing spinal cord and nerve compression, treating joint instabilities and deformities, limb lengthening
What tests may be offered if a child has a skeletal dysplasia?
Genetic testing of the child and family
Connective tissue disorders are generally disorders of what? What does this result in?
Mainly a disorder of type I collagen synthesis, resulting in joint hyper mobility
What are the 4 main connective tissues? Embryologically, where do these come from?
Bone, cartilage, tendons and ligaments. These come from the mesoderm.
In connective tissues, what is the exception which is mainly composed of type II collagen?
Articular (hyaline) cartilage
How can Marfan’s Syndrome be inherited?
Sporadic or autosomal dominant
Where is the mutation in Marfan’s Syndrome? What is this required for?
Fibrillin gene- a scaffold for elastin
What are the major features of Marfan’s Syndrome?
Tall stature with disproportionately long limbs, hyper mobility (lax ligaments) and arachnodactyly
What are some more specific features of Marfan’s Syndrome?
High arched palate, scoliosis, pectus excavatum, spontaneous pneumothorax
What are some ocular problems which Marfan’s can cause?
Lens dislocation, glaucoma, retinal detachment
Cardiac abnormalities may cause premature death in Marfan’s Syndrome. What are some features?
Aortic aneurysms, valve incompetence (particularly mitral regurgitation)
Why are joint dislocations a problem in Marfan’s Syndrome?
Stabilisations do not work because the biological abnormality cannot be corrected
Generalised familial joint laxity is normally inherited how?
Autosomal dominant
People with generalised lax ligaments are more prone to what problems?
Soft tissue injury e.g. ankle sprain and recurrent dislocations of joints (especially shoulder and patella)
Ehlor’s Danlos Syndrome is usually inherited how? It involves defects in a number of genes involved in what?
Autosomal dominant: genes involved in collagen and elastin formation
What are the main features of Ehlor’s Danlos Syndrome?
Scoliosis, joint hypermobility and dislocations, vascular fragility and ease of bruising
Stabilisation can be performed for dislocating joints in Ehlor’s Danlos Syndrome. Why can this be a problem?
Can have issues with bleeding and wound healing can be poor
Down’s syndrome causes short stature and joint laxity which can predispose to what?
Recurrent dislocations (especially patella) and OA, atlanto-axial instability and spinal cord compression
How are muscular dystrophies inherited? What does this mean?
X-linked recessive, hence they only affect boys
Where is the defect in muscular dystrophy?
The dystrophin calcium gene
What does muscular dystrophy lead to?
Progressive muscle weakness and wasting as the boy gets older
What are some indications of / tests for muscular dystrophy?
Gower’s sign, raised CK, muscle biopsy
Children with muscular dystrophy will usually be unable to do what by age 10? What will then ensue?
Unable to walk by age 10. Then progressive respiratory and cardiac failure until death in the early 20s.
What are some supportive treatments for muscular dystrophy?
Physiotherapy, splintage, deformity correction
How is Becker’s muscular dystrophy different to Duchenne?
Becker’s is less severe, boys will usually be able to walk in their teens and will survive into 30s/40s
When should children be screened for muscular dystrophy?
If there is a positive family history
