Lecithin:cholesterol acyltransferase (LCAT) is a key enzyme involved in reverse cholesterol transport from the peripheral tissues to the liver. LCAT deficiency, in which this enzyme is congenitally absent, is a genetic disease that impairs the esterification of free cholesterol in the plasma, leading to accumulation of phospholipids, including lecithin, in the organs of the body; the clinical manifestations include corneal opacities, normochromic anemia, renal disorder, etc. The prognosis is determined by the degree of renal dysfunction, and renal biopsy specimens reveal characteristic light- and electron-microscopic findings. The disease, transmitted by autosomal recessive inheritance, is extremely rare. There have only been 88 gene mutations of the LCAT gene reported around the world, and 13 of them are from Japan. One of the characteristics of LCAT deficiency is the strong correlations among the patterns, extent and phenotypes of these gene mutations.