I have a trait that was measured using a assay but a large proportion of the samples where below the threshold for detection of the assay so my phenotype isnt normally distributed and transformation (log, sqrt, box-cox) isn't successful. Is it better then to treat the data as continous for gwas or categorical high-low. The only thing is with high-low, there would be individuals with phenotype values close to the distinction between the two. Advise would be much appreciated. The distribution is below
I was hoping to use gcta software for the gwas.