Huntington's Flashcards
What is Huntington’s chorea
Huntington’s chorea is an autosomal dominant genetic condition that involves a genetic mutation in the HTT gene on chromosome 4. (trinucleotide repeat disorder)
What does anticipation refer to in Huntington’s chorea
Huntington’s chorea displays something called genetic “anticipation”. Anticipation is a feature of trinucleotide repeat disorders. This is where successive generations have more repeats in the gene, resulting in:
Earlier age of onset
Increased severity of disease
Presentation of Huntington’s
Chorea (involuntary, abnormal movements)
Eye movement disorders
Speech difficulties (dysarthria)
Swallowing difficulties (dysphagia)
Cognitive and psychiatric problems
Mx of Huntington’s chorea
MDT SALT Genetic counselling Advanced directives End of life care planning
Medications that can suppress disordered movement in Huntington’s
Antipsychotics
Benzodiazepines
Dopamine-depleting agents(tetrabenazine)
What is charcot-marie-tooth disease
Autosomal dominant disease that affects peripheral motor and sensory nerves
Features of charcot-marie-tooth disease
High foot arches (pes cavus)
Distal muscle wasting causing “inverted champagne bottle legs”
Weakness in the lower legs, particularly loss of ankle dorsiflexion
Weakness in the hands
Reduced tendon reflexes
Reduced muscle tone
Peripheral sensory loss
Causes of peripheral neuropathy
A – Alcohol B – B12 deficiency C – Cancer and Chronic Kidney Disease D – Diabetes and Drugs (e.g. isoniazid, amiodarone and cisplatin) E – Every vasculitis
Mx of Charcot-marie-tooth disease
Neurologists and geneticists to make the diagnosis
Physiotherapists to maintain muscle strength and joint range of motion
Occupational therapists to assist with activities of living
Podiatrists to help with foot symptoms and suggest insoles and other orthoses to improve symptoms
Orthopaedic surgeons to correct disabling joint deformities
What is a Charcot joint
It describes a joint which has become badly disrupted and damaged secondary to a loss of sensation
Used to most commonly caused by neuropathy secondary to syphilis but now mostly in diabetics
Features of Charcot joint
Charcot joints are typically a lost less painful than would be expected given the degree of joint disruption due to the sensory neuropathy.
However, 75% of patients report some degree of pain
the joint is typically swollen, red and warm
What is neurofibromatosis
genetic condition that causes nerve tumours (neuromas) to develop throughout the nervous system
Gene associated with neurofibromatosis type 1
The neurofibromatosis type 1 gene is found on chromosome 17. It codes for a protein called neurofibromin, which is a tumour suppressor protein.
Inheritance of mutations in this gene is autosomal dominant.
Diagnosis of neurofibromatosis
At least 2 of 7 features in CRABBING
CRABBING features in neurofibromatosis
C – Café-au-lait spots (6 or more) measuring ≥ 5mm in children or ≥ 15mm in adults
R – Relative with NF1
A – Axillary or inguinal freckles
BB – Bony dysplasia such as Bowing of a long bone or sphenoid wing dysplasia
I – Iris hamartomas (Lisch nodules) (2 or more) are yellow brown spots on the iris
N – Neurofibromas (2 or more) or 1 plexiform neurofibroma
G – Glioma of the optic nerve
