A case of acquired generalized lipodystrophy with cerebellar degeneration and type 2 diabetes mellitus

The Mevalonate Pathway Is Indispensable for Adipocyte Survival

The mevalonate pathway is essential for the synthesis of isoprenoids and cholesterol. Adipose tissue is known as a major site for cholesterol storage; however, the role of the local mevalonate pathway and its synthesized isoprenoids remains unclear. In this study, adipose-specific mevalonate pathway-disrupted (aKO) mice were generated through knockout of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase (HMGCR). aKO mice showed serious lipodystrophy accompanied with glucose and lipid metabolic disorders and hepatomegaly. These metabolic variations in aKO mice were dramatically reversed after fat transplantation. In addition, HMGCR-disrupted adipocytes exhibited loss of lipid accumulation and an increase of cell death, which were ameliorated by the supplementation of mevalonate and geranylgeranyl pyrophosphate but not farnesyl pyrophosphate and squalene. Finally, we found that apoptosis may be involved in adipocyte death induced by HMGCR down-regulation. Our findings indicate that the mevalonate pathway is essential for adipocytes and further suggest that this pathway is an important regulator of adipocyte turnover.

Acquired generalized lipodystrophy associated with autoimmune hepatitis and low serum C4 level

Lipodystrophies are a group of diseases characterized by loss of fat tissue and are associated with insulin resistance. A six-year-old girl followed with the diagnosis of autoimmune hepatitis showed a severe loss of fat tissue, hyperinsulinemia, impaired glucose tolerance, hypertriglyceridemia and low serum complement 4 (C4) levels. She had coarse facial features with generalized loss of subcutaneous fat and prominent muscularity. Remarkable acanthosis nigricans was present over the neck, axilla, and umbilicus. Two hours after glucose loading, the glucose tolerance test revealed a glucose level of 258 mg/dL, a HbA1c value of 6.8%, and an insulin level of 642.9 mIU/mL, documenting a state of insulin resistance and type 2 diabetes mellitus. Acquired generalized lipodystrophy was diagnosed and metformin with dietary intervention was initiated. Low serum complement levels proved the autoimmune nature of the process. We conclude that the serum complement levels must be investigated in patients with acquired lipodystrophy, particularly when it is associated with autoimmune hepatitis.