Mucopolysaccharidosis IIIB (also known as Sanfilippo syndrome B) is caused by variants in the alpha-N-acetylglucosaminidase (NAGLU) gene and has been previously characterized at the clinical and molecular level in humans, emus11, cattle12, knockout mice13, and transgenic swine14,15. Here, NAGLU is linked to mucopolysaccharidosis type 3B.