Abstract
Purpose: :
To demonstrate the clinical utility of molecular genetic analysis in two cases of monoclonal gammopathy of undetermined significance (MGUS) manifesting secondary corneal features, such as corneal depositions, suggestive of two different inherited corneal dystrophies.
Methods: :
Two patients with reported corneal dystrophies due to corneal deposits were studied using slit-lamp examination. In addition, screening of TGFBI and UBIAD1 genes on collected DNA of the two patients were performed. Systemic evaluation was also performed to identify conditions associated with secondary corneal amyloidosis.
Results: :
A 60-year-old Caucasian woman demonstrated bilateral, linear deep stromal opacities, characteristic of atypical late-onset variant lattice corneal dystrophy, but subsequent screening of TGFBI exons 4, 11, 12, 13, 14 did not reveal any pathogenic or novel mutations. Similarly, a 67-year-old Caucasian woman presented bilateral, axially-distributed, needle-like crystalline deposits, initially diagnosed as corneal crystals associated with Schnyder corneal dystrophy. However, screening of UBAD1 failed to reveal pathogenic or novel mutations. Both patients were referred for further systemic evaluation, which revealed MGUS in each, presumed to be the source of the corneal protein deposition.
Conclusions: :
Corneal opacities seemingly characteristic of an inherited corneal dystrophy may be secondary to a systemic disorder associated with secondary corneal deposition. In these two cases, corneal depositions were, in fact, associated with the myeloproliferative disorder MGUS. In cases that demonstrate an atypical phenotype or clinical history, such as lack of a family history, molecular genetic analysis should be performed initially, and, if negative, followed by a systemic evaluation for conditions associated with corneal protein deposition.
Keywords: clinical laboratory testing