Glomerulopathy with Homozygous Apolipoprotein E2: A Report of Three Cases and Review of the Literature
A 66-year-old male was referred to our center by his primary care physician because of the increase of proteinuria. He was diagnosed with diabetes at the age of 50 years but remained untreated. At the age of 60 years, he started voglibose at the diabetes center of our hospital. At the age of 66 years, urinary abnormality of protein 3+ and occult blood 1+ was pointed out, combined with simple diabetic retinopathy and a serum creatinine level of 0.96 mg/dl. He was referred to our center for further investigation, and a renal biopsy was performed. One of 11 glomeruli showed global sclerosis, and the other glomeruli showed massive foam cell infiltration in the glomerular capillaries and mildly expanded mesangium (fig. ). These foam cells immunohistochemically stained positive for cluster differentiation 68 (CD68) (not shown). Transmission electron microscope images also revealed foam cell infiltration mainly located in the capillaries containing scattered lipid droplets and lamellar bodies in their cytoplasm (fig. ). The glomerular basement membrane (GBM) showed mild thickening, and nodular lesions were formed in some glomeruli. The interstitium and tubules showed mild fibrosis and atrophy (25% of the cortical region), and a moderate degree of arteriolar hyalinosis was also found. No interstitial foamy cells or foamy tubular degeneration was found. Immunofluorescence study revealed no significant glomerular deposits. The patient's lipid profile showed type III HLP (table ). Apolipoprotein phenotype analysis showed a homozygosity of apoE2. A further DNA sequence analysis was performed as described previously [] and showed a nucleotide substitution of cysteine for arginine at codon 158 (Arg158Cys) of the apoE gene and no other mutations. Eicosapentaenoic acid was added to his statin therapy, but he progressed to end-stage renal failure and was started on dialysis 8 years after the diagnosis.