DEGS1, also known as Δ4 -dihydroceramide desaturase 1, is a key enzyme in the sphingolipid pathway. It acts in the last step of de novo ceramide biosynthesis, converting dihydroceramide to ceramide. Sphingolipids are crucial as membrane constituents and signaling molecules, involved in fundamental processes like cell differentiation, neuronal signaling, and myelin sheath formation [2,4,5].

Pathogenic variants in DEGS1 are associated with hypomyelinating leukodystrophy (HLD), a disorder affecting the formation of the myelin sheath in the central nervous system. In affected patients, genomic sequencing has identified various variants in DEGS1, such as a homozygous missense variant (c.565A > G:p Asn189Asp) with conflicting pathogenicity reports, but follow-up sphingolipid analysis showed raised dihydroceramide/ceramide ratios, indicating Des1 protein dysfunction [1]. In other studies, patients with DEGS1-related HLD presented with severe motor arrest, early nystagmus, dystonia, spasticity, and failure to thrive, along with hypomyelination, thinning of the corpus callosum, and progressive thalamic and cerebellar atrophy on MRI [5]. Lipidomic analysis in affected individuals demonstrated augmented levels of dihydroceramides and related species, consistent with DEGS1 malfunction [3,4]. In zebrafish models, knockdown of DEGS1 and treatment with fingolimod, which inhibits Cer synthase one step prior to DEGS1, reduced the dihydroceramide/ceramide imbalance and locomotor disability, increasing myelinating oligodendrocytes [5].

In conclusion, DEGS1 is essential for sphingolipid metabolism, especially in the final step of ceramide biosynthesis. Research on DEGS1-related disorders, including studies using zebrafish knockdown models, has provided insights into the pathophysiology of hypomyelinating leukodystrophy. Understanding the role of DEGS1 in these processes may offer potential therapeutic strategies for related neurological disorders.