The SP-triggered PGD2 ratio (i.e. PGD2 level after SP stimulation divided by basal PGD2 level) was significantly higher in MCAD patients (median: 2.05; P < 0.001) than in healthy controls (median: 0.88), with wide ranges for both MCAD patients (0.79-6.64) and healthy controls (0.40-1.34) (Table 2). Here, PTGDS is linked to medium chain acyl-CoA dehydrogenase deficiency.