LCAT, key to HDL particle formation

Lecithin-Cholesterol Acyl Transferase (LCAT) is a critical enzyme in the cholesterol metabolism. It helps transport cholesterol from the periphery, including diseased coronary arteries, back to the liver via formation of mature HDL particles (“good cholesterol”).

LCAT deficiency due to genetic mutations is rare. It leads to a profound low HDLc <10 mg/dL, in turn causing corneal opacities, target cell hemolytic anemia, and renal failure. Treatment is mainly supportive.

Authors have identified an acquired immune-mediated form of LCAT deficiency. It is the 7th case worldwide. It lead to nephrotic syndrome, but the patient responded well to the anti-inflammatory agent, prednisolone.

Although these are rare illnesses, they help us understand lipid physiology deeper, and more importantly to provide quick and effective treatment.

GT

Also see:

Lipoproteins

Dyslipidemia


J. Clinical Lipidology

Case Report

August 2018

Background

Recessive inherited disorder lecithin-cholesterol acyltransferase (LCAT) deficiency causes severe hypo-cholesterolemia and nephrotic syndrome. Characteristic lipoprotein subfractions have been observed in familial LCAT deficiency (FLD) with renal damage.

Objective

We describe a case of acquired LCAT deficiencies with literature review.

Methods

The lipoprotein profiles examined by gel permeation–high-performance liquid chromatography (GP-HPLC) and native 2-dimensional electrophoresis before and after prednisolone treatment.

Results

Here we describe the case of a 67-year-old man with severely low levels of cholesterol. The serum LCAT activity was undetectable, and autoantibodies against it were detected. The patient developed nephrotic syndrome at the age of 70 years.

Renal biopsy revealed not only membranous glomerulonephritis but also lesions similar to those seen in FLD. We initiated prednisolone treatment, which resulted in remission of the nephrotic syndrome.

In GP-HPLC analysis, lipoprotein profile was similar to that of FLD although lipoprotein X level was low. Acquired LCAT deficiencies are extremely rare with only 7 known cases including ours.

Patients with undetectable LCAT activity levels develop nephrotic syndrome that requires prednisolone treatment; cases whose LCAT activity levels can be determined may also develop nephrotic syndrome, but spontaneously recover.

Conclusion

Lipoprotein X may play a role in the development of renal impairment in individuals with FLD. However, the effect might be less significant in individuals with acquired LCAT deficiency.