AGXT and asthma: The genotype-dependent effect on sphingolipid synthesis was demonstrated in a cohort of asthmatic children from New York using targeted blood sphingolipidomics and metabolic labeling of peripheral blood mononuclear cells (PBMCs) with the serine palmitoyltransferase (SPT) substrate, serine [26], supporting the longstanding hypothesis that sphingolipid synthesis is decreased in asthma [13,18,27], especially in children [28].