On the basis of the marked basal release of PGD2 in MCAD-patients, we expanded PGD2 analysis by investigating AA-, ASA-, and SP-triggered release of PGD2, since these triggering factors are routinely used in standard FET analysis and are of relevance in MCAD. The gene discussed is PTGDS; the disease is medium chain acyl-CoA dehydrogenase deficiency.