Polymorphisms in the human DNA ligase I gene (LIG1) including a complex GT repeat
K J Livak1, W A Little, S L Stack
1Research and Development Division, The Du Pont Merck Pharmaceutical, Wilmington, DE 19880-0328, USA. livakkn@perkin-elmer.com
Mutation Research
|January 27, 1999
Summary
Human DNA ligase I sequencing revealed new sequence variations. These include a polymorphic single base change and a three-base deletion due to alternative splicing, impacting gene transcripts.
Area of Science:
- Molecular Biology
- Genetics
Background:
- Human DNA ligase I is crucial for DNA replication and repair.
- Previous sequencing of human DNA ligase I cDNA revealed specific sequences.
Purpose of the Study:
- To investigate unreported differences in human DNA ligase I cDNA sequence.
- To characterize sequence variations and their functional implications.
Main Methods:
- DNA sequencing of cDNA clones from HeLa cells.
- Polymerase Chain Reaction (PCR) amplification of specific gene segments.
- Sequence analysis of amplified DNA and cDNA.
- Primer extension reactions.
Main Results:
- Two unreported differences were found: a single base change and a three-base deletion in exon 6.
- Intron 6 size was corrected to approximately 2.6 kb.
- The single-base change in exon 6 is a common polymorphism (allele frequency 0.5).
- The three-base deletion results from alternative splicing, present in one-third of transcripts in HeLa cells and thymus.
- A complex, polymorphic GT repeat was identified in intron 6.
Conclusions:
- The study identified novel sequence variations in human DNA ligase I.
- These variations, including a common polymorphism and alternative splicing, contribute to transcript diversity.
- The identified intron 6 repeat is polymorphic and requires specialized methods for detection.
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