Fabry Disease with Genetic Variants of Unknown Significance and Concomitant Immunoglobulin A Nephropathy.

Introduction: The diagnosis of Fabry disease (FD) with genetic variants of unknown significance (VUSs) is relatively difficult. We explored patients with novel VUS variants and concomitant immunoglobulin A nephropathy (IgAN) to improve the understanding of VUS.

Methods: The study retrospectively investigated patients with genetically confirmed FD. Probands with VUS were selected from the database of FD patients who underwent genetic analysis. Demographic, clinicopathological, and laboratory data from probands and family members were collected and analyzed.

Results: Fourteen probands and their family members were included in the study. The probands were divided into group 1 (patients with VUS, n = 5) and group 2 (patients with pathologic/likely pathologic variants, n = 9). The group 1 included 2 missense mutations and 1 deletion mutation, while the group 2 included 6 missense mutations and 2 deletion mutations. There were no significant differences in gender, age, serum creatinine, eGFR, and proteinuria between the two groups. IgA deposition with myeloid bodies was found in all VUS patients. The cardiac involvement in group 2 was more severe than that in group 1. Seven families performed the pedigree analysis, and after the comprehensive evaluation, two GLA variants (c.479C>A, p.Ala160Asp; c.1032-1058 del, p.Ser345_Met353del) were upgraded from VUS to the likely pathogenic.

Conclusion: The clinical manifestations of FD are heterogeneous. FD often coexists with nephrotic disorders, such as IgAN and MCD. Comprehensive evaluation, especially tissue-specific biopsy, is necessary for patients with GLA-VUSs. Two GLA variants (c.479C>A, p.Ala160Asp; c.1032-1058 del, p.Ser345_Met353del) were upgraded from VUS to the likely pathogenic after the comprehensive evaluation.