Hereditary sensory and autonomic neuropathy type 1 (HSAN1/HSN1) is a peripheral neuropathy most commonly associated with pathogenic variants in the <i>serine palmitoyltransferase complex (SPTLC1, SPTLC2)</i> genes, which are responsible for sphingolipid biosynthesis. The gene discussed is SPTLC1; the disease is hereditary sensory and autonomic neuropathy type 1.