DSEL (dermatan sulfate epimerase like) encodes a Golgi membrane-localized enzyme with chondroitin-glucuronate 5-epimerase activity involved in dermatan sulfate and chondroitin sulfate proteoglycan biosynthesis 1. The gene participates in decorin synthesis, a protein critical for normal collagen formation 1. DSEL plays a regulatory role in chondrocyte development, as circCOL1A2 upregulates DSEL expression through competing endogenous RNA mechanisms to inhibit chondrocyte proliferation and chondrogenic differentiation 2. Clinically, DSEL alterations associate with multiple congenital and developmental conditions. Deletions and mutations in DSEL have been identified in patients with diaphragmatic hernia, though its definitive role in diaphragm development remains uncertain 1. Array-CGH analysis identified DSEL among 11 candidate genes potentially related to congenital diaphragmatic hernia occurrence 3. Additionally, DSEL variants show association with type 2 diabetes susceptibility in North African populations 4, and elevated DSEL expression occurs in nasopharyngeal carcinoma samples 5. Recent studies identified a DSEL RNA editing site as an independent prognostic factor in lower-grade gliomas, contributing to a four-site RNA editing signature for survival prediction 6. These findings suggest DSEL functions in extracellular matrix regulation and exhibits dysregulation across developmental and oncological disease contexts.