Clinical Dilemma of Corneal Opacity, Very Low High-density Lipoprotein, and Nephrotic Syndrome: Mystery Revealed.

Lecithin-cholesterol acyltransferase (LCAT) is a liver enzyme necessary for the formation of cholesteryl esters in plasma from free cholesterol. The rare autosomal recessive disease resulting from familial deficiency of this enzyme can lead to nephropathy with kidney involvement generally being the most common cause of death. In addition, the disease process can engender corneal opacity, very low high-density lipoprotein, normochromic anemia, and nephropathy. We present this case of a 35-year-old male who initially visited for a second opinion for renal failure and nephrotic range proteinuria. He underwent renal biopsy which displayed focal segmental glomerulosclerosis-type injury pattern and was started on futile high-dose steroid therapy. A second renal biopsy coincided with the development of corneal opacity leading to a confirmatory testing of LCAT deficiency through biochemistry panel.

A novel pathogenic variant in LCAT causing FLD. A case report.

BACKGROUND: Fish-eye disease (FED) is due to a partial deficiency in LCAT activity. Nevertheless, Familial lecithin-cholesterol acyltransferase deficiency (FLD), also called Norum disease, appears when the deficiency is complete. They are both rare genetic disorders inherited in an autosomal recessive manner. Clinical signs include decreased circulating HDL cholesterol and dense corneal opacity. Kidney injuries also affect patients suffering from FLD. The diagnosis of FLD is based on the presence of characteristic signs and symptoms and confirmed by genetic testing. CASE PRESENTATION: We present a case of a 63-year-old man showing an altered lipid profile with low HDL cholesterol, chronic kidney disease (CKD) and corneal disorders. He was referred to genetic counseling in order to discard genetic LCAT deficiency due to decreased visual acuity caused by corneal opacity. A massive DNA sequencing was conducted using a multigene panel associated with lipid metabolism disturbances. RESULTS AND GENETIC FINDINGS: Two likely pathogenic variants in LCAT were identified and later confirmed by Sanger sequencing. Both (c.491 G > A and c.496 G > A) were missense variants that originated an amino acid substitution (164Arginine for Histidine and 166Alanine for Threonine, respectively) modifying the protein sequence and its 3D structure. CONCLUSIONS: FLD and FED sharing common biochemical features, and the existence of other diseases with similar clinical profiles underline the need for a timely differential diagnosis aiming to address patients to preventive programs and future available therapies. This case, added to the reduced number of publications previously reported regarding FLD and FED, contributes to better understanding the genetic characteristics, clinical features, and diagnosis of these syndromes.