Analytical units (AU). The number of single copy genes s bounded by pairs of duplicates on chromosomes 1 and 2 is the sum of those on chromosome 1 and chromosome 2. The last two pairs of duplicates on chromosomes 1 and 2 do not bound an AU because one of the genes between them has a paralog on chromosome 3.
Sankoff et al. BMC Genomics 2010 11:313 doi:10.1186/1471-2164-11-313