UASt regulatory sequences drive expression of the LanB1 open reading frame, mutated to carry a Q1722X amino acid substitution. This change is analagous to a M1721Nfs5 change in the orthologous human LAMB1 gene, a pathogenic variant associated with LAMB1-related leukoencephalopathy. The coding sequence is tagged at the C-terminal end with three copies of Tag:HA. The human ORF is flanked by a pair of incompatible FRT sites (FRT5 and FRT2), which allows for future in vivo exchange of either the promoter or tag sequence.