Diagnosis of fructose-1,6-bisphosphatase deficiency using cultured lymphocyte fraction: a secure and noninvasive alternative to liver biopsy.

We report the result of enzymatic and molecular analyses, using cultured lymphocyte fractions (cultivated monocytes), of six Japanese patients (from five families) and one Italian patient with fructose-1,6-bisphosphatase (FBPase) deficiency. Enzymatic analysis demonstrated FBPase deficiency in all seven patients, including the Italian patient whose fructose-1,6-bisphosphatase activity has been reported to be normal in leukocytes but deficient in liver. Molecular analysis of the FBPase gene identified pathogenic mutations in only 8 among the total 12 alleles of six families. We have thus demonstrated the validity of using cultured monocytes as a secure and noninvasive alternative to liver biopsy for accurate diagnosis of FBPase deficiency.