In this review, we outline the most abundant GBA1 mutations, highlight the link between GBA1 gene variants and the courses of most prevalent α-synucleinopathies, as well as discuss the mechanisms by which dysfunction of glucocerebrosidase (GBA1 gene product) might impact α-synuclein accumulation and α-synucleinopathies progression. This evidence concerns the gene SNCA and synucleinopathy.