Novel six-nucleotide deletion in the hepatic fructose-1,6-bisphosphate aldolase gene in a patient with hereditary fructose intolerance and enzyme structure-function implications

Hereditary fructose intolerance (HFI) is an autosomal recessive human disea se that results from the deficiency of the hepatic aldolase isoenzyme, Affe cted individuals will succumb to the disease unless it is readily diagnosed and fructose eliminated from the diet, Simple and noninvasive diagnosis is now possible by direct DNA analysis that scans for known and unknown mutat ions, Using a combination of several PCR-based methods (restriction enzyme digestion, allele specific oligonucleotide hybridisation, single strand con formation analysis and direct sequencing) we identified a novel six-nudeoti de deletion in exon 6 of the aldolase B gene (Delta 6ex6) that leads to the elimination of two amino acid residues (Leu182 and Val183) leaving the mes sage inframe, The three-dimensional structural alterations induced in the e nzyme by Delta 6ex6 have been elucidated by molecular graphics analysis usi ng the crystal structure of the rabbit muscle aldolase as reference model, These studies showed that the elimination of Leu182 and Val183 perturbs the correct orientation of adjacent catalytic residues such as Lys146 and Glu1 87.