Depending on the location of the mutations in the GLB1 gene and on their combination in compound heterozygous individuals, the molecular pathophysiology of the resulting β-galactosidase protein can produce a spectrum of phenotypic presentations, ranging from primarily neurologic manifestations in GM1-gangliosidosis, to primarily skeletal involvement in MBD. This evidence concerns the gene GLB1 and Marchiafava-Bignami disease.