Identifying nineteenth century genealogical links from genotypes

Area of Science:

• Genetics
• Computational Biology
• Genealogy

Background:

• Identifying genealogical relationships is crucial for genetic studies.
• Tasmanian population has a high degree of shared ancestry from mid-nineteenth century founders.
• Previous genealogical research identified some relationships within the study cohort.

Purpose of the Study:

• To develop and test a likelihood-based method for detecting distant genealogical relationships from genomewide genetic data.
• To identify previously unknown relative pairs within a cohort of Tasmanians with multiple sclerosis.

Main Methods:

• A likelihood method was developed to compare genotypes of multiple individuals.
• Genomewide microsatellite markers at 4 cM density were used for genotyping.
• The algorithm was tested on known relative pairs and then applied to the entire cohort.

Main Results:

• The method demonstrated good power to identify relationships up to degree eight (e.g., third cousins once removed).
• 61 new putative relative pairs were identified among cases, with a 10% false discovery rate.
• The method successfully identified previously known relationships within the cohort.

Conclusions:

• The developed likelihood method is effective for identifying moderately distant genealogical relationships using genomewide data.
• This approach can aid genealogists and researchers in gene-mapping studies, especially in populations with limited historical records.
• Increased marker density (e.g., SNPs) is expected to further enhance the power of this method.