Maximum-likelihood estimation of recent shared ancestry (ERSA)
- Chad Huff1,
- David Witherspoon1,
- Tatum Simonson1,
- Jinchuan Xing1,
- Scott Watkins1,
- Yuhua Zhang1,
- Therese Tuohy1,
- Debra Neklason1,
- Randall Burt1,
- Stephen Guthery2,
- Scott Woodward3 and
- Lynn B Jorde1,4
- * Corresponding author; email: lbj{at}genetics.utah.edu
Abstract
Accurate estimation of recent shared ancestry is important for genetics, evolution, medicine, conservation biology, and forensics. Established methods estimate kinship accurately for first- through third-degree relatives. We demonstrate that chromosomal segments shared by two individuals due to identity by descent (IBD) provide much additional information about shared ancestry. We developed a maximum-likelihood method for the estimation of recent shared ancestry (ERSA) from the number and lengths of IBD segments derived from high-density SNP or whole-genome sequence data. We used ERSA to estimate relationships from SNP genotypes in 169 individuals from three large, well-defined human pedigrees. ERSA is accurate to within one degree of relationship for 97% of first- through fifth-degree relatives and 80% of sixth- and seventh-degree relatives. We demonstrate that ERSA's statistical power approaches the maximum theoretical limit imposed by the fact that distant relatives frequently share no DNA through a common ancestor. ERSA greatly expands the range of relationships that can be estimated from genetic data and is implemented in a freely available software package.
- Received October 7, 2010.
- Accepted February 1, 2011.
- Copyright © 2011, Cold Spring Harbor Laboratory Press
