The magnitude of the RRs far exceeded the reductions in mortality that were predicted on the basis of enhanced dialytic removal of β2M (Fig 5), e.g. less than 8% for comparisons of HF vs. LF, short-daily or long-daily, and HDF vs. LF, HF or short-daily when KR was 2 ml/min. The gene discussed is B2M; the disease is hydrops fetalis.