Integration of PCR-sequencing analysis with multiplex ligation-dependent probe amplification for diagnosis of hereditary fructose intolerance

Abstract

Mutations in the ALDOB gene impair the activity of the hepatic aldolase B enzyme, causing hereditary fructose intolerance (HFI), an inherited autosomic recessive disease of carbohydrate metabolism, that can result in hypoglycemia, liver and kidney failure, coma, and death. Noninvasive diagnosis is possible by identifying mutant ALDOB alleles in suspected patients. We report the genetic characterization of a cohort of 18 HFI Caucasian patients, based on PCR-sequencing and Multiplex Ligation-dependent Probe Amplification (MLPA), with the identification of two novel genetic lesions: A small duplication c.940_941dupT (p.Trp314fsX22) and a large deletion encompassing the promoter region and exon 1. MLPA and long range-PCR (LR-PCR) also identified the recently reported g.7840_14288del6448 allele with a surprisingly high frequency (11%) within our patients’ cohort. The most common p.Ala150Pro (44%), p.Ala175Asp (19%), p.Asn335Lys (8%), and/or the known c.360-363del4 (5%), p.Tyr204X (2.8%), IVS6 −2A>G (2.8%) mutant alleles were identified in 14 patients at a homozygous or compound-heterozygous level. The integration of PCR-sequencing analysis with exon-dosage tools [MLPA and quantitative fluorescent multiplex-PCR (QFM-PCR)] led to the full genotyping of patients within our cohort and to the identification of the new deletion encompassing the promoter region and exon 1.