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The complex pathology of trinucleotide repeats
1Department of Biology and Center for Cancer Research, Room E17-541, Massachusetts Institute of Technology, 40 Ames Street, Cambridge, MA 02139, USA. sanjeeva_reddy@sequana.co
Current Opinion in Cell Biology
|June 1, 1997
Summary
Trinucleotide repeat expansion causes over ten human disorders. These diseases are classified into two types based on whether the repeat expansion occurs in coding or noncoding gene regions, impacting disease mechanisms.
Area of Science:
- Genetics
- Molecular Biology
- Human Pathology
Background:
- Trinucleotide repeat (TNR) expansions are linked to at least ten human genetic disorders.
- A common feature is repeat instability during germline transmission above a critical length.
Purpose of the Study:
- To categorize TNR disorders into distinct groups.
- To differentiate the molecular mechanisms underlying Type I and Type II TNR disorders.
Main Methods:
- Review of existing literature on TNR disorders.
- Classification based on repeat sequence (CAG) and location (coding vs. noncoding).
- Mention of ongoing research using mouse models and biochemical/cell biological approaches for Type I disorders.
Main Results:
- TNR disorders are divided into two groups: Type I and Type II.
- Type I disorders involve CAG repeat expansions encoding polyglutamine in coding regions of broadly expressed genes.
- Type II disorders involve repeat expansions in noncoding gene regions.
Conclusions:
- CAG repeat expansions in coding regions (Type I) lead to polyglutamine-induced pathology.
- Repeat expansions in noncoding regions (Type II) may have diverse pathogenic mechanisms.
- Further research is needed to fully elucidate the mechanisms of Type II disorders.