Czech nationwide screening for Fabry disease in patients on maintenance dialysis: a call for evaluation of population-enriched gene variants of uncertain significance.

BACKGROUND

Fabry disease (FD) is a rare disorder caused by variants in the GLA gene encoding α-galactosidase A (GALA), leading to end-stage kidney disease (ESKD), among other health issues. The 2002 Czech nationwide FD screening in ESKD found undiagnosed cases in dialysis patients by examining GALA activity in dried blood spots (DBS).

METHODS

The second nationwide FD screening (2016-2018; 21-month study) in ESKD patients on maintenance dialysis therapy (MDT) included 112 Czech dialysis units to assess country-wide FD diagnostic guidelines' efficacy in reducing its underdiagnosis. This involved GALA activity and/or lyso-Gb3 levels with sequencing in positive males, the latter applied first in all females, followed by lyso-Gb3 examination in variant-positive cases. Screening-positive cases were referred to the FD center for follow-up and studies.

RESULTS

The 6352 screened cases represent 93.9% of all MDT patients within the study duration. Eight variants were identified in 39 patients, of which seven were in 35 ESKD cases classified as likely benign (LB), with normal lyso-Gb3 levels in all subjects. Four patients (three males with reduced GALA activity and one sequencing-positive female) bear a "hot variant of uncertain significance" (VUS) c.1181T>C(p.Leu394Pro), significantly enriched compared to the general population, suggesting its association with FD.

CONCLUSIONS

This is one of the largest FD screening schemes in a European ESKD cohort. Subsequent studies proved that the hot VUS is linked to alternative FD pathogenesis, thereby substantiating the utility of combining biomarkers and sequencing/bioinformatics in FD screening. The broad application of FD diagnostic guidelines has reduced its underdiagnosis in ESKD.