BSCL2 and diabetes mellitus: Berardinelli–Seip congenital lipodystrophy type 2 (BSCL2) gene encodes the protein seipin.1 Mutations of BSCL2 are associated with generalized lipodystrophy characterized by a near-complete absence of adipose tissue and early-onset metabolic complications, such as insulin resistance and diabetes.1, 2, 3 Seipin is an integral endoplasmic reticulum (ER) membrane protein with two transmembrane domains, cytosolic N- and C-termini, and a central loop domain in the ER lumen.4, 5 Various adipocyte-associated functions of seipin have been proposed.