Rapid Detection of Twenty-Nine Common Chinese Glucose-6-phosphate Dehydrogenase Variants Using a Matrix-Assisted Laser Desorption/ionization-Time of Flight Mass Spectrometry Assay on Dried Blood Spots.

BACKGROUND:Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common inherited disease. Current neonatal screening methods for G6PD deficiency primarily rely on the use of biochemical tests. However, only 15%-20% of female carriers were estimated to have been detected using these tests. As a better alternative, DNA-based tests could be used for G6PD deficiency screening. We aimed to develop a matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) assay for G6PD variant detection.METHODS:A MALDI-TOF MS assay with multiprimer extension (multi-PEX) was developed to rapidly and accurately detect the 29 common G6PD variants in the Chinese population using a dried blood spot as a template. A parallel study screening 571 unrelated neonatal samples using the MALDI-TOF MS and fluorescence quantitative enzymatic assays was performed. All results were confirmed by Sanger sequencing in a blind study.RESULTS:In 571 unrelated neonatal samples, 34 positive samples, including 26 samples from hemizygous males and eight samples from heterozygous females, were correctly identified, yielding a clinical sensitivity of 100%. The results were validated using Sanger sequencing with 100% concordance. In contrast, the fluorescence quantitative enzymatic assay had a 75% false negative and 88.8% false positive rate for the detection of heterozygous G6PD deficient females.CONCLUSIONS:We established a reliable MALDI-TOF MS assay for G6PD deficiency screening in the Chinese population maximizing the chance of detection of heterozygous G6PD deficient females and reducing the false negative and false positive rates associated with routinely used newborn screening procedures.