NAGLU and mucopolysaccharidosis type 3B: Mucopolysaccharidosis type IIIB (MPSIIIB), characterized by deficiency of α-N-acetylglucosaminidase (NAGLU) and subsequent accumulation of HS, manifests cognitive decline typically appearing between age 2 and 4 years, predominantly affecting the CNS but also impacting somatic organs and leading to premature mortality.