ASAH1 and lymphangioleiomyomatosis: To determine whether the sphingolipid biosynthesis pathway (Figure 2A) is activated in LAM, we compared gene expression data from non-LAM female lungs (n = 15) with LAM lungs (n = 14) and found that ASAH1 and DEGS1 transcript levels were significantly higher in LAM (Figure 2, B and C; Supplemental Figure 1; and Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.166850DS1; P < 0.0001 Mann-Whitney test).