Clinical evaluation of a melting curve analysis-based PCR assay for glucose phosphate dehydrogenase gene mutation detection

Abstract

To evaluate the clinical value of multicolor melting curve analysis(MMCA) for detecting genetic mutations in G6PD deficiency. A total of 402 peripheral blood samples(256 males and 146 females) were collected from suspected patients or their relatives at the Prenatal Diagnosis Center of Liuzhou Maternal and Child Health Hospital between March 2012 and May 2012. The samples were screened by G6PD/6PGD quantitative ratio testing. The reliability of the assay was evaluated by multiplex probe melting curve assay(which can detect 16 G6PD mutations) and DNA sequencing through a double blind study. One hundred seventy cases with G6PD/6PGD ratio < 1.0 and 232 cases with G6PD/6PGD ratio ≥ 1.0 were detected by the enzymological method. DNA sequencing has identified 182 wild type samples, 151 hemizygous mutation samples, 5 female homozygous mutation samples, 54 female heterozygous mutation samples and 10 female double heterozygous mutation samples. Multicolor melting curve analysis has detected 185 wild type samples, 148 hemizygous mutation samples, 5 female homozygous mutation samples, 55 female heterozygous mutation samples and 9 female double heterozygous mutation samples. The specificity and sensitivity of G6PD gene mutation detection by multicolor melting curve analysis were 100%(182/182) and 98.6%(217/220), respectively. The positive predictive value and negative predictive value were 99.5%(216/217) and 98.4%(182/185), respectively, and the Youden's index was 0.986. The concordance rate of the sample detection between the melting curve assay and DNA sequencing was 99.0%(398/402). Twenty-one different genotypes were detected by the multicolor melting curve analysis and 24 different genotypes were detected by DNA sequencing. Four samples containing mutations(c.196T>A or c.406C>T) were not detected by multicolor melting curve analysis, which can be attributed to different technical settings of the two methods. Multicolor melting curve analysis for G6PD gene mutation detection is a simple, rapid, sensitive and specific method, which can be used for clinical diagnosis of G6PD deficiency.