HEXA and Tay-Sachs disease: The first family presented a missense COL4A6 variant (NM_033641.4: c.1480G>A p.(Gly494Arg)), accounting for hearing loss, while a likely pathogenic HEXA variant (NM_000520.6: c.902T>G p.(Met301Arg)) explained Tay-Sachs disease features.