To determine the relationship between β-hexosaminidase and AD, we investigated whether a heterozygous deletion of Hexb, the gene that encodes the beta subunit of β-hexosaminidase, modifies the behavioural phenotype and appearance of disease lesions in AppNL-G-F/NL-G-F(AppKI/KI) mice. The gene discussed is HEXB; the disease is Alzheimer disease.