Very low HDL levels: clinical assessment and management

ABSTRACT In individuals with very low high-density lipoprotein (HDL-C) cholesterol, such as Tangier disease, LCAT deficiency, and familial hypoalphalipoproteinemia, there is an increased risk of premature atherosclerosis. However, analyzes based on comparisons of populations with small variations in HDL-C mediated by polygenic alterations do not confirm these findings, suggesting that there is an indirect association or heterogeneity in the pathophysiological mechanisms related to the reduction of HDL-C. Trials that evaluated some of the HDL functions demonstrate a more robust degree of association between the HDL system and atherosclerotic risk, but as they were not designed to modify lipoprotein functionality, there is insufficient data to establish a causal relationship. We currently have randomized clinical trials of therapies that increase HDL-C concentration by various mechanisms, and this HDL-C elevation has not independently demonstrated a reduction in the risk of cardiovascular events. Therefore, this evidence shows that (a) measuring HDL-C as a way of estimating HDL-related atheroprotective system function is insufficient and (b) we still do not know how to increase cardiovascular protection with therapies aimed at modifying HDL metabolism. This leads us to a greater effort to understand the mechanisms of molecular action and cellular interaction of HDL, completely abandoning the traditional view focused on the plasma concentration of HDL-C. In this review, we will detail this new understanding and the new horizon for using the HDL system to mitigate residual atherosclerotic risk.

A Case of Familial Lecithin-cholesterol Acyltransferase (LCAT) Deficiency

PURPOSE: To report a case of a familial lecithin cholesterol acyltransferase (LCAT) deficiency patient with bilateral corneal opacities. CASE SUMMARY: A 26-year-old man with bilateral corneal opacities visited our hospital. We took slit lamp examination, corneal thickness measurement, corneal endothelial cell counts and fundus examination. Blood and urine tests were included. Kidney biopsy was done. The tissues were observed by a light microscopy and an electron microscopy. Hemolytic anemia, proteinuria, hematuria, hypertriglyceridemia, decreased HDL cholesterol level, and lecithin cholesterol acyltransferase (LCAT) deficiency were found. At kidney biopsy, electron-lucent vacuoles and lamellar inclusion body were found. CONCLUSIONS: Bilateral corneal opacities can be an imporant clinical sign of systemic disease which is caused by abnormal lipid metabolism like the familial lecithin cholesterol acyltransferase (LCAT) deficiency.