Check this option to use K-Means clustering via SAS PROC FASTCLUS to reduce the number of markers.Note : This option is intended to be used for speeding up the computations when there are many markers in the input data set. When you choose to use this option, only a subset of representative markers are used in the linkage map analysis.Note : You should drop any monomorphic markers as well as any markers with many missing values from the input data set to get the best possible results from this analysis.