DESeq2 genes which vary between 4 groups

It sounds like you want to do a likelihood ratio test in order to capture genes whose variances differ across your four groups. If this is the case, then you will likely want to perform, for example:

dds <- DESeqDataSetFromMatrix(..., design= ~ group)
dds <- DESeq(dds, test = 'LRT', reduced = ~1)
res <- results(dds)

Please take a look at the 'likelihood ratio test' section of the vignette.

Kevin