Genetic disorders/Diseases Flashcards
Huntington’s disease
- Trinucleotide repeats is used to diagnose HD
- HD gene is on short arm of chromosome 4
Wilson’s disease
- Low serum ceruloplasmin
Acute intermittent porphyria
Excessive amounts of urine prphobilinogens and aminolevulinic acide in urine
- Presents as abdominal pain, tachycardia, tingling in hands and feet, paranoia and hallucinaitons
Lambert-eaton myasthenic syndrome
paraneoplastic abnormality of PREsynaptic acetylcholine release, often described in conjunction with small-cell lung carcinoma
- likely immune mediated against voltage gated calcium channels on the presynaptic side of the nueromuscular junction
- generalized weakness with initial improvement after minimal exercise
Guillain Barre syndrome
acute inflammatory demyelinating polyneuropathy (AIDP) is a rapidly occurring demyelinating disease that can present with ascending pain, paralysis
- loss of deep tendon reflexes in the extremities
- tests of choice EMG and nerve conduction studies which reveal loss of H reflex and decreased nerve conduction velocities
Polymyositis
Inflammatory disease of the muscle
Tuberous sclerosis
- Autosomal dominant
- Nuerocutaneous disorder with a prevalence of about 1 in 6000-9000 individuals
- seizures, mental retardation
- cutaneous lesions include: ash leaf spot (hypomelanotic macule), adenoma sebaceum (facial angiofibromas), shagreen spots (irregularly shaped often raided or textures skin lesions on the back or flank), retinal haratomas
- neuropathologic lesions inlcude: subependymal nodules and cortical hamartomas
Rett’s disorder
Pervasive developmental disorder only seen in girls, involves deceleration of head growth from ages 5 months to 4 years, loss of purposeful hand skills and development of stereotyped hand movements between 5 months and 2.5 years, loss of social engagement and acquired impairment in expressive and receptive language skills, seizures observed in up to 75% of patients
NF 1
- Cafe-au-lait spots, subcutaneous neurofibromas, axillary freckling, lisch nodules (pigmented iris hamartomas), optic nerve gliomas, neurofibroms, and schwannomas.
- caused by a mutation of NF1 gene on chromosome 17
NF2
- Chromosome 22
- bilateral vestibular (nerve 8) schwannomas
Williams
-AD
-mental retardation
- hemizygous deletion that includes the elastin locus on chromosome 7q11-q23.
- short stature, depressed nasal bridge, broad forehead, widely spaced teeth, elphin like facies
- thyroid, renal and cardiovasacualr abnormalities
- anxiety, hyperactivity, hypermusicality
What chromosomes are associated with Alzheimers
long arm of 21 (gene for amyloid precursor protein) and 19 (apo E4 gene)
Turners syndrome
female but with no secondary sex characteristics and an absence or minimal development of gonads
- one x chromosome
klinefelters syndrome
presence of an extra chromosome, xxy
-male habitus but do not develop strong male characteristics
-small, underdeveloped genitals, infertile and can develop breast tissue
What is myasthenia gravis?
Autoimmune neurologic disorder involving the production of autoantibodies against postsynaptic nicotinic acetylcholinergic receptor sites on muscle
- offending antibodies cross placenta to fetus
- clinical features: diplopia, dysarthria, bulbar palsy, fatigue and muscle weakness
- deep tendon reflexes are preserved
- relationship between MG and thymoma- 10% of pts with MG have thymoma
- Edrphonium chloride is a short acting cholinergic agent used to diagnose the disorder clinically, other diagnostic tests include EMG and nerve conduction studies (decreased amplitude on repetitive stimulation), titer of serum antibodies
- Pyrostigmine is used to treat the disorder on an ongoing basis, can also use steriods, plasmapharesis, IVIG, immunosupressive agents such as azathioprine
Duchenne’s muscular dystrophy
-X linked recessive
- due to lack of muscle dystrophin (a protein found in muscle membrane)
- muscle weakness greater proximally
- Diminished DTR, elevated CPK, mental retardation (1/3 of cases), enlarged muscles due to fat infiltration