Discord
From ISOGG Wiki
Discordant alleles are those which cannot arise from Mendelian inheritance. For instance, if at a particular SNP, the mother's alleles are AA and the father's are TT, then if a child is anything other than AT the results would be considered discordant. This might arise from genotyping error, from microdeletions being misinterpreted as homozygous, or from de novo mutations.