Uniformity refers to how evenly distributed is the coverage for the gene.
The average number of bases that spans the coding exon is calculated for the base on the gene and the percentage of bases greater than 20% of the average is defined as the “Gene Uniformity”.
For example :
The beginning of the target might have high coverage with 1000x, but the end might only have 40x coverage = low uniformity
Uniformity of 90% means 90% of the bases (within a target) is within 20% of the average.