Neuroscience Test 1 - Rett Syndrome
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- What kind of diagnosis is made with Rett Syndrome?
- Clinical because not all presentations have the mutation.
- How are babies with Rett Syndrome described?
- Good, quiet babies...too quiet.
- Shortly after birth, there is a deceleration in the growth of what?
- The head
- Babies with Rett syndrome are often mis-diagnosed with what?
- Autism
- What is characteristic about the child's overall progression?
- They develop purposeful hand movements and vocabulary and then lose them.
- When do the stereotypic hand movements present?
- During the day; 12-18 months
- How would you describe the gait of someone with this disorder?
- Apraxic
- What about the patient's breathing is a characteristic of Rett?
- Hyperventilation and breath holding
- What are the girls at an increased risk for?
- Scoliosis
- Is this disease recurrent in families?
- No
- Where is the genetic variation?
- The X chromosome
- How are some girls more heavily affected than others?
- Skewed x-inactivation
- Can Rett syndrome girls conceive?
- Yes they undergo puberty at a normal time.
- What percentage of normal brain weight do Rett syndrome patients have?
- 60-70%
- What is the normal life expectancy?
- 35 years of age
- What specific areas of the brain are reduced?
- Frontal, temporal and the caudate and substantia nigra (melanin areas)
- Is there neurodegeneration in these patients?
- No there is only loss of neuron size due to small dendritic arbor.
- What protein is affected in Rett syndrome? What is its job?
- Methyl-CpG binding protein 2; transcriptional repressor
- What sort of gradient in normal tissues is seen with the affected protein?
- Rostral to caudal
- What domain of the protein binds to the CpG dinucleotide? What exons?
- Methyl binding domain; 3 and 4
- What are the two active domains in the affected protein?
- MBP and TRD
- What are milder forms of the disease associated with in relation to the mutation
- Seen in the C-terminus
- Which variant of the affected protein is expressed highly in the brain?
- MecP2b
- Phenotypes seen in females (6)
-
1. Rett Syndrome
2. Speech Variant
3. Delayed onset 3-4 years
4. Mild learning disabilities
5. Angelman syndrome
6. Normal carriers - Phenotypes in males (4)
-
1. Fatal encephalopathy
2. Rett/Klinefelter
3. X-linked mental retardation
4. Somatic mosaicism - What mutation is the most severe in Rett syndrome?
- Nonsense mutations
- Were there differences in severity based on the two active sites?
- No
- Mis-sense mutations in the C-terminus had a phenotype of?
- X-linked mental retardation
- What is being used as a therapy for Rett syndrome?
- Folate-betaine as a CpG binding protein alternative
- What are some ocular problems that can develop in Rett patients?
- Temporary strabismus
- What is the abnormal positioning of the joint that is prevelant in Rett patients?
- Dystonia
- Which areas of the brain do you see a reduction of size in with Rett patients?
- Frontal, temporal caudate and pigmented areas