Neutral lipid storage disease with myopathy

Alternate names

NLSDM; Neutral lipid storage disease without ichthyosis

Definition

Neutral lipid storage disease with myopathy is a condition in which fats (lipids) are stored abnormally in organs and tissues throughout the body. The accumulation of fats in muscle tissue leads to muscle weakness (myopathy).

Epidemiology

Neutral lipid storage disease with myopathy is a rare condition; its incidence is unknown.

Cause

Mutations in the PNPLA2 gene cause neutral lipid storage disease with myopathy. The PNPLA2 gene provides instructions for making an enzyme called adipose triglyceride lipase (ATGL). The ATGL enzyme plays a role in breaking down fats called triglycerides. Triglycerides are an important source of stored energy in cells. These fats must be broken down into simpler molecules called fatty acids before they can be used for energy.

Gene mutations

PNPLA2 gene mutations impair the ATGL enzyme's ability to break down triglycerides. These triglycerides then accumulate in muscle and tissues throughout the body, resulting in the signs and symptoms of neutral lipid storage disease with myopathy.

Inheritance

Autosomal recessive inheritance, a 25% chance

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Signs and symptoms

• People with this condition have muscle weakness (myopathy) due to the accumulation of fats in muscle tissue.
• Other features of this condition may include a fatty liver, a weakened and enlarged heart (cardiomyopathy), inflammation of the pancreas (pancreatitis), reduced thyroid activity (hypothyroidism), and type 2 diabetes (the most common form of diabetes).
• Signs and symptoms of neutral lipid storage disease with myopathy vary greatly among affected individuals.

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

• Fatty replacement of skeletal muscle
• Increased intramyocellular lipid droplets
• Progressive proximal muscle weakness
• Shoulder girdle muscle weakness(Weak shoulder muscles)

30%-79% of people have these symptoms

• Abnormal circulating creatine kinase concentration(Abnormal levels of creatine kinase in blood)
• Cardiomyopathy(Disease of the heart muscle)
• Difficulty running
• Difficulty walking(Difficulty in walking)
• Easy fatigability
• Elevated hepatic transaminase(High liver enzymes)
• Fasciculations(Muscle twitch)
• Generalized [[hypotonia](Decreased muscle tone)
• Gowers sign
• Hepatic steatosis(Fatty infiltration of liver)
• Hypertriglyceridemia(Increased plasma triglycerides)
• Increased lactate dehydrogenase level
• Motor delay
• Myalgia(Muscle ache)
• Myopathy(Muscle tissue disease)
• Pelvic girdle muscle weakness
• Very long chain fatty acid accumulation

5%-29% of people have these symptoms

• Areflexia(Absent tendon reflexes)
• Chronic pancreatitis(Chronic pancreas inflammation)
• Congestive heart failure(Cardiac failure)
• Diabetes mellitus
• Foot dorsiflexor weakness(Foot drop)
• Generalized limb muscle atrophy(Generalized muscle wasting)
• Hand muscle weakness
• Hepatomegaly(Enlarged liver)
• Intellectual disability, mild(Mental retardation, borderline-mild)
• Neck muscle weakness(Floppy neck)
• Progressive distal muscle weakness
• Rimmed vacuoles
• Sensorineural hearing impairment
• Short stature(Small stature)

1%-4% of people have these symptoms

• Cholecystitis(Gallbladder inflammation)
• Delayed ability to walk
• Pineal cyst

Diagnosis

These disorders are characterized by the presence of triglyceride-containing cytoplasmic droplets in leukocytes and in other tissues, including bone marrow, skin, and muscle.

Treatment

• To date, there is no treatment for the underlying metabolic problem.
• Current therapies include adhering to strict dietary guidelines and utilizing treatments focused on the associated symptoms.
• A recent study suggests that people with this condition may benefit from bezafibrate (a medication used to treat high cholesterol) treatment, particularly with respect to lipid accumulation and fat oxidative capacity.
• Additional studies into this therapy are needed.

NIH genetic and rare disease info

• NIH info on Neutral lipid storage disease with myopathy

Neutral lipid storage disease with myopathy is a rare disease.

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