Familial partial lipodystrophy type 2

Other Names: FPLD2; Lipodystrophy, familial partial, Dunnigan type; Lipodystrophy, familial, of limbs and lower trunk; Lipodystrophy, reverse partial; Lipoatrophic diabetes; FPL2; Lipodystrophy, familial partial, type 2; Dunnigan syndrome; Familial partial lipodystrophy, Dunnigan type

Familial partial lipodystrophy type 2 (FPLD2) is a rare, genetic disorder that affects the amount and distribution of fat (adipose tissue) in the body.

Onset

Symptoms typically develop around puberty, after having normal adipose tissue in childhood.

Cause

FPLD2 is caused by mutations in the LMNA gene. LMNA and the other genes associated with familial partial lipodystrophy provide instructions for making proteins with a variety of functions, including important roles in fat storage. In particular, these proteins play important roles in the development and function of adipocytes, which are the fat-storing cells in adipose tissue. Mutations in any of the genes associated with familial partial lipodystrophy reduce or eliminate the function of their respective proteins, which impairs the development, structure, or function of adipocytes and makes the body unable to store and use fats properly. These abnormalities of adipose tissue alter hormone production and affect many of the body's organs. However, it is unclear why the changes cause fat to be lost in some parts of the body and stored abnormally in others.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

Most cases of familial partial lipodystrophy, including type 2, are inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Signs and symptoms

FPLD2 causes a loss of adipose tissue from the limbs, torso, buttocks and hips, while causing a buildup of adipose tissue in the face, neck, and upper back. It may also cause increased musculature. Some people with FPLD2 have areas of dark, thick skin (acanthosis nigricans), and females may have excessive hairiness (hirsutism) and menstrual abnormalities. Metabolic abnormalities develop in adolescence or adulthood, leading to signs and symptoms that may include insulin resistance, dyslipidemia, diabetes, pancreatitis (or recurrent acute pancreatitis), liver steatosis, atherosclerosis, and an increased risk of heart disease.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Diabetes mellitus
• Hepatomegaly(Enlarged liver)
• Hypertriglyceridemia(Increased plasma triglycerides)
• Insulin resistance(Body fails to respond to insulin)
• Lipoatrophy(Loss of fat tissue in localized area)
• Round face(Circular face)
• Skeletal muscle hypertrophy(Increased skeletal muscle cells)
• Xanthomatosis(Yellow bumps of fatty deposits on skin)

30%-79% of people have these symptoms

• Abnormality of the nail
• Acute pancreatitis(Acute pancreatic inflammation)
• Advanced eruption of teeth(Early eruption of teeth)
• Loss of subcutaneous adipose tissue in limbs(Loss of fat tissue below the skin in limbs)
• Secondary amenorrhea(Previous menstrual periods stop)
• Thin skin

5%-29% of people have these symptoms

• Abnormality of complement system
• Abnormality of skeletal muscle fiber size
• Acanthosis nigricans(Darkened and thickened skin)
• Cellulitis(Bacterial infection of skin)
• Congestive heart failure(Cardiac failure)
• Coronary artery atherosclerosis(Plaque build-up in arteries supplying blood to heart)
• Cranial nerve paralysis
• Dysmenorrhea(Painful menstruation)
• Eclampsia
• Generalized hirsutism(Excessive hairiness over body)
• Glomerulopathy
• Hepatic steatosis(Fatty infiltration of liver)
• Hypertrophic cardiomyopathy(Enlarged and thickened heart muscle)
• Myalgia(Muscle ache)
• Myopathy(Muscle tissue disease)
• Pancreatitis(Pancreatic inflammation)
• Polycystic ovaries
• Splenomegaly(Increased spleen size)

Diagnosis

Molecular Genetics Tests

• Deletion/duplication analysis
• Sequence analysis of select exons
• Sequence analysis of the entire coding region
• Mutation scanning of the entire coding region
• Targeted variant analysis

Treatment

Treatment aims to correct metabolic abnormalities and manage complications. This may involve medications, monitoring the diet, and exercise. Plastic surgery may be considered by some individuals. People with FPL2 are encouraged to seek counseling and support after being diagnosed, as the disorder can cause anxiety and psychological distress. The long-term health outlook generally depends on the severity of complications such as diabetes, pancreatitis, and heart disease.

NIH genetic and rare disease info

• NIH info on Familial partial lipodystrophy type 2

Familial partial lipodystrophy type 2 is a rare disease.

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