My presentation described genetic and acquired varieties of lipodystrophies (excluding the lipodystrophy syndrome in HIV-infected patients). These lipodystrophies have been known for more than 100 years, and are characterized by selective loss of body fat that can vary from small indentations or depressed areas in patients with localized lipodystrophies to near complete absence of adipose tissue in generalized lipodystrophies. Depending upon the extent of body fat loss, patients may or may not have insulin resistance and its metabolic complications such as hyperlipidemia and glucose intolerance. For example, patients with localized lipodystrophies do not have insulin resistance, but those with generalized lipodystrophies have severe insulin resistance.
The lipodystrophies can be classified into two broad categories: 1. Familial or Genetic and 2. Acquired. The two main types of familial lipodystrophies are an autosomal recessive, congenital generalized lipodystrophy (CGL) and an autosomal dominant, familial partial lipodystrophy, Dunnigan type (FPLD). Patients with CGL have near complete lack of metabolically active adipose tissue since birth but mechanical adipose tissue is well preserved. Patients with FPLD lose subcutaneous fat from the extremities at puberty and tend to accumulate excess fat in the face and neck. The FPLD gene was recently localized to chromosome 1q21-22, but the genetic basis of CGL and FPLD has yet to be elucidated. Patients with FPLD share some features with HIV-infected patients developing lipodystrophies such as the loss of subcutaneous fat from the extremities and excess fat in anterior neck region (double-chin appearance). FPLD patients, however, accumulate excess fat on the face and do not develop a buffalo-hump. In contrast, almost all HIV-patients with lipodystrophy lack facial fat and some develop buffalo-humps.
Patients with acquired generalized lipodystrophy have generalized loss of subcutaneous fat but those with acquired partial lipodystrophy have fat loss limited to face, trunk and upper extremities. Autoimmunity underlies both types of acquired lipodystrophies, which occur more commonly in females, usually starting during childhood. Almost all patients with acquired partial lipodystrophy have low complement C3 levels and have circulating autoantibody called C3 nephritic factor. One-third develop membranocapillary glomerulonephritis (a kidney disease). Localized lipodystrophies can be due to drugs (at the site of injection of insulin, steroids), repeated pressure at a site, panniculitis (inflammation of adipose tissue), due to centrifugal variety (a rare disease described mainly in Japan), or due to unknown mechanisms.
Current management of patients with lipodystrophy includes cosmetic surgery, diet and drug therapy for control of diabetes and dyslipidemia.