Add this description to the Sequence Phase Relationship page as part of an introduction: A sequence phase relationship asserts a specific type of relationship between two variants or haplotypes. Humans inherit a copy of each autosome from mother and father - each cell contains, for instance, a maternally-derived and a paternally-derived chromosome 7. We refer to the two chromosomes as 'homologous', and we can refer to each of the chromosomes as 'homologs'. Where a person has two variants (or haplotypes) on chromosome 7, those variants can both be on the same homolog (i.e. both variants are on the maternally-derived chromosome), or those variants can be on different homologs (i.e. one variant is on the maternally-derived chromosome and one variant is on the paternally-derived chromosome). Where the two variants are on the same homolog, the variants are said to be in a 'Cis' relationship. Where the two variants are on different homologs, the variants are said to be in a 'Trans' relationship.