CAS PS 231 Lecture Notes - Lecture 14: Hypoplasia, Ubiquitin Ligase, Basal Ganglia
31 May 2016
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Document Summary
This chapter concerns the study of mechanisms underlying brain damage that occurs due to genetic anomalies and/or non-traumatic environmental causes. The lecture will focus on selected developmental disorders and neurodegenerative disorders. Fragile x mental retardation (fmr) 1:4000 males and 1:8000 females. Occurs in all races and ethnic groups and accounts for approximately 10% of all males with severe intellectual disabilities and 10% of mild intellectual disabilities. Due to the expansion of a trinucleotide repeat (cgg)n in the fmr1 gene, which is on the x chromosome. Normal: between 5 and 54 copies of cgg repeat. Unaffected carriers: 55 200 cgg repeats (called a premutation) > 200 repeats causes full mutation, which results in methylation of the gene. Not enough fragile-x mental retardation protein, or fmrp, is produced. Exact role of fmrp is unknown, but it may regulate protein synthesis. Expressed highly in neurons (particularly dendritic spines) Learning defects may be tied to dendritic alterations in the hippocampus.
