The insertion of Velocigene cassette ZEN-Ub1 created a deletion of size 8162bp between positions 49536744-49544905 of Chromosome 4 (Build GRCm39). The cassette replaced 3' of exon 2 through 5' of exon 9. Enzyme activity assays of liver lysates revealed that activity toward fructose 1-phosphate was undetectable, and resulted in a change in the fructose 1,6-bisphosphate:fructose 1-phosphate activity ratio from 1.7 in wild-type mice to over 10 in homozygous mutant mice, indicating that any remaining aldolase activity was due to aldolase A.