This theme emerged from 12 articles and ranged across the different disorders, including MLD [27,28], cerebral adrenoleukodystrophy [30,31], SMA1 [35,36], TSD [41], Mucopolysaccharidosis Type IIIA [42], Angelman syndrome [48,49], retinal dystrophy [51] and WAS [52]. This evidence concerns the gene SMN1 and Tay-Sachs disease.