Heavy-Chain Amyloidosis in TGFBI-Negative and Gelsolin-Negative Atypical Lattice Corneal Dystrophy

Abstract

An atypical case of late-onset lattice corneal dystrophy is described in a 61-year-old man without a family history of eye disease. Mutational analysis of the TGFBI gene excluded any pathogenic sequence variants. However, 2 years later, renal impairment and nephrotic syndrome were diagnosed, resulting in a diagnosis of systemic heavy-chain amyloidosis. Slit-lamp examination, corneal photography, and in vivo confocal microscopy were performed. General systemic evaluation included blood and urine assessment, bone marrow and renal biopsies, and cardiologic evaluation. A DNA sample underwent initial mutational analysis of TGFBI and, subsequently, gelsolin. The renal biopsy sample was subject to direct protein sequencing by mass spectrometry. A bilateral, atypical, fine, midperipheral lattice corneal dystrophy with minor central subepithelial scarring was clinically characterized. Subsequently, abnormal renal functions with proteinuria, IgG lambda paraproteinemia, extensive deposition of amyloid in renal glomeruli, and increased plasma cells in bone marrow were identified. No pathogenic sequence mutations were identified in TGFBI or the gelsolin genes. Direct protein sequencing by mass spectrometry showed amyloid to be heavy-chain deposition rather than the more usual light-chain deposition. Atypical midperipheral lattice corneal dystrophy presenting with adult onset and negative family history should arouse suspicion for an association with paraproteinemias or amyloidosis. Exclusion of TGFBI mutations should alert the clinician to the possibility of potentially life-threatening conditions, with referral for careful systemic evaluation.