Apart from the metabolic hypothesis, it cannot be ruled out that genetic variants, for example in the genes encoding the different subunits of the SPT, are associated with elevated 1-deoxySLs, in at least some of the cases, as it is for example known in patients with hereditary sensory and autonomic neuropathy type 1 (HSAN1) [30]. Here, AGXT is linked to hereditary sensory and autonomic neuropathy type 1.