Evaluating DNA sequence variants of unknown biological significance

Area of Science:

• Molecular Genetics
• Genomic Analysis

Background:

• Assessing the biological significance of DNA sequence variants is crucial in molecular genetics.
• Large genes like BRCA1 and BRCA2 serve as important models for variant analysis.

Purpose of the Study:

• To describe various approaches for determining the biological significance of DNA variants.
• To highlight challenges and considerations in variant interpretation.

Main Methods:

• Literature and database review for previously described variants.
• Analysis of co-inheritance patterns and evolutionary conservation.
• Assessment of variant effects on protein function using methods like Grantham assessment and functional domain identification.
• Population and family-based studies to analyze variant distribution.

Main Results:

• Previously described variants can be identified through literature and database searches, though databases have limitations.
• Evolutionary conservation and co-inheritance patterns provide clues to variant significance.
• Functional domain analysis and Grantham assessment predict protein-level effects.
• Tumor sample analysis showing loss of a variant suggests it is not deleterious.
• Variant significance is typically determined by integrating multiple lines of evidence.

Conclusions:

• No single parameter definitively determines a DNA variant's biological significance.
• A comprehensive approach integrating diverse data is essential for accurate variant interpretation.
• Multiple lines of evidence are necessary to establish the biological impact of genetic variants.