新生児GM1ガングリオシドーシスにおける新規ガラクトシダーゼ-ベータ-1バリアント：症例報告

GM1 gangliosidosis is an autosomal recessive lysosomal storage disorder caused by pathogenic GLB1 variants that impair β-galactosidase activity, resulting in GM1 ganglioside accumulation. The infantile (type I) form is the most severe. We describe the case of a one-year-old girl born to consanguineous parents who presented with developmental regression, hypotonia, coarse facial features, hepatosplenomegaly, macular cherry-red spots, Mongolian spots, and sensorineural hearing loss. Whole-exome sequencing revealed a novel homozygous GLB1 variant, NM_000404.4:c.1525T>A (p.Trp509Arg), absent from population databases and predicted deleterious by in silico tools. According to the American College of Medical Genetics and Genomics guidelines, it is classified as a variant of uncertain significance, though the phenotype-genotype match suggests pathogenicity. This case broadens the GLB1 mutational spectrum and underscores the value of early genetic testing for diagnosis, counseling, and management.