L-Serine-d7 is intended for use as an internal standard for the quantification of L-serine by GC- or LC-MS. L-Serine is a non-essential amino acid. It is produced from 3-phosphoglycerate in a multistep biosynthesis catalyzed by phosphoglycerate dehydrogenase (PGDH), phosphoserine aminotransferase (PSAT), and phosphoserine phosphatase (PSP). L-Serine can also be derived from dietary sources, as well as protein and phospholipid turnover. Defective L-serine biosynthesis is associated with neural tube defects and deoxysphingolipid accumulation in patients with Neu-Laxova syndrome, a rare disease characterized by a mutation in PGDH.Dysregulation of L-serine phosphorylation is associated with disease progression in patients with neurodegenerative diseases, including Alzheimer’s disease and amyotrophic lateral sclerosis.