Evaluation of GLA variants detected in newborn screening for Fabry disease using biomarker analysis

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by pathogenic variants in the GLA gene, resulting in deficient or dysfunctional α-galactosidase A (AGAL) activity. Newborn screening (NBS) enables early detection and management; however, ascertaining the pathogenicity of unknown GLA variants remains a diagnostic challenge. This study aimed to evaluate the clinical significance of GLA gene variants detected through NBS in Japan, utilizing biochemical, genetic, and structural analyses. A total of 22 individuals, including newborns and their relatives carrying GLA gene variants, were analyzed. Plasma AGAL activity, plasma globotriaosylsphingosine (Lyso-Gb3), and urinary globotriaosylceramide levels were measured. In silico predictions, structural modeling, and variant classification databases were employed to assess pathogenicity. Significant reductions in AGAL activity and elevated Lyso-Gb3 levels were observed in variants, such as p.R112H and p.K391E, suggesting a high likelihood of being pathogenic variants. Variants like p.W209R, p.I242T, p.M267T, and p.R356Q demonstrated mild biochemical abnormalities, indicating limited pathogenic potential or non-pathogenicity. Variants, such as p.E66Q and c.-10C > T, showed no significant biochemical effects, indicating that they are benign. This study underscores the diverse pathogenicity of GLA gene variants identified through NBS, emphasizing the need for integrated diagnostic strategies, including biomarker analysis, structural assessments, and long-term clinical follow-up. These findings contribute to improving genotype-phenotype correlations and optimizing diagnostic precision for FD.