PTGDS and medium chain acyl-CoA dehydrogenase deficiency: Therefore, markedly elevated PGD2 release from PBLs of MCAD patients, as measured by the PGD2-supplemented FET assay, might at least in part reflect mast cell activity, and PBLs might serve as suitable specimens for analyzing mast cell activity and individual eicosanoid release patterns of MCAD patients.