An allelic discrimination plot, also known as a "cluster plot" or an "AD plot" is shown below. Ideally, these plots show three clusters, and near the origin, the No Template Control (NTC). These clusters are described in the table below. The points in each cluster are grouped closely together, and each cluster is well separated from the other clusters.  

A Typical three-cluster allelic discrimination plot


Assignment of clusters in an allelic discrimination plot

Samples Containing... Are grouped in...
Allele X (homozygote), labeled with VIC® dye Lower right corner of the plot
Allele Y (homozygote), labeled with FAM™ dye Upper left corner of the plot
Both (allele X and allele Y—heterozygote) Approximately midway between the allele X and allele Y clusters
No template control (NTC) Bottom left corner of the plot
Undetermined Anywhere on the plot