ObjectivesTo investigate the clinical value of the melting curve analysis-based PCR assay for the clinical genetic diagnosis and prenatal diagnosis of β-thalassemia.Methods A total of 451 peripheral blood samples,including 372 cases with β-thalassemia phenotypes and 79 cases without β-thalassemia phenotypes,were collected by Liuzhou Municipal Maternity and Child Healthcare Hospital between January 2011 and August 2011.Moreover,another 84 cases,including 16 fetal villi samples (10 - 13 weeks),64 amniotic fluid samples (16 -24 weeks ) and 4 umbilical cord blood samples (above 17 weeks),whose parents were β-thalassemia carriers,were also collected for this assay between June 2011 and September 2011.A double-blind test was done to compare the detection reliability of the melting curve analysis-based assay (24 β-thalassemia mutations can be detected) with PCR-RDB probe assay (17 β-thalassemia mutations can be detected ) and DNA sequencing using these samples.The wildtype,mutant and total concordance rates of the genotyping results were calculated separately among the melting curve analysis based assay,PCR-RDB probe assay and DNA sequencing.Results Among the 451 peripheral blood samples,thirteen mutations and nineteen genotypes were obtained by using melting curve analysis-based assay.447 samples had the same detection results and 4 samples had different detection results by comparing melting curve analysis-based assay with PCR-RDB probe assay,thus,the concordance rate of the sample detection result was 99.1％ (447/451),and the concordance rate of the allele detection result was 99.6％ (898/902).DNA sequencing results of the 4 samples showed that 3 samples had the same genotyping result with melting curve analysis-based assay,and 1 sample had the same genotyping result with PCR-RDB probe assay.A rare β-globin mutation which was not included by melting curve analysis-based assay was not detected.Thus,the genotypes of 450 samples were detected accurately by melting curve analysis-based assay,and the concordance rate of the sample detection between the melting curve assay and DNA sequencing assay was 99.8％ (450/451).Among 84 fetal villi,amniotic fluid,and umbilical cord blood samples,8 mutation types and 18 genotypes were obtained by using melting curve analysis-based assay.All the samples have the same detection results by comparing melting curve analysis-based assay with PCR-RDB probe assay and DNA sequencing,so the concordance rate of the genotyping results was 100％ among the melting curve analysis-based assay,PCR-RDB probe assay and DNA sequencing.Conclusions The melting curve analysis-based PCR assay can detect multiple unknown samples simultaneously,and detect multiple mutations accurately.It is very useful for the genetic diagnosis and prenatal diagnosis of β-thalassemia.

Objective To study genotypes in nonsyndromic hearing loss (NSHL ) patients from Guangxi Zhuang Autonomous Region hearing speech rehabilitation center using DNA microarray in combination with Sanger sequencing .Methods Deaf patients received routine physical and otorhinolaryngoloical examinations as well as pure tone autiometry .Brainstem auditory evoked potential test was performed in uncooperative children .Blood samples were obtained from a total of 136 patients ,male 81 ,female 55 ,age from one year five month to seventeen ,having nonsyndromic hearing loss .Genomic DNA was extracted and then 9 hot mutation spots in 4 susceptibility genes were detected by DNA microarray .GJB2 and SLC26A was further detected by Sanger sequencing in the patients with negative results and heterozygotes .Results Among the 136 patients with nonsyndromic hearing loss ,20 cases were positive for GJB2 gene ,SLC26A4 gene or mitochondrial 12SrRNA gene mutations .There were 14 .71% (20/136)patients were positive for hot mutation spots in the deafness related genes ,25% (34/136)patients carried muta‐tions of deafness related genes using DNA microarray in combination with Sanger sequencing .Six SLC26A4 rare mutations (c .259G> T ,c .754C> T ,c .1229C> T ,c .1548_1549insC ,c .1705+5A>G and c .2086C> T) were de‐tected by Sanger sequencing .c .235delC was the most common mutation in GJB2 gene .c .919-2A>G ,c .754C> T and c .1229C> T were the common mutations in SLC26A4 gene .The mutation rate of GJB2 and SLC26A4 was 38 . 24% .and 58 .82% ,respectively .Conclusion Prevalent deafness-associated gene mutations in the nine loci studied were less frequently detected in nonsyndromic hearing loss patients from Guangxi Zhuang Autonomous Region hear‐ing speech rehabilitation center .It can improve the detection rate of deafness gene mutations by using gene microar‐ray in combination with Sanger sequencing .GJB2 and SLC26A4 are the common causative genes .

Objective: To analyze variations of TYR and P genes among 14 patients with clinically diagnosed oculocutaneous albinism. Methods: Potential variations of the TYR and P genes were detected by Sanger sequencing. Novel variations were predicted with bioinformatics software including SIFT and PolyPhen-2. Results: No variation was found in the TYR gene, while 9 types of variations were found in the P gene among the 14 patients, which included c. 803-3C>G (7/26), c. 1327G>A (p.Val443Ile) (5/26), c. 632C>T (p.Pro211Leu) (4/26), c. 1832T>C (p.Leu611Pro) (3/26), c. 1349C>A (p.Thr450Lys) (2/26), c. 2363C>T (p.Ser788Leu) (2/26), c. 2228C>T (p.Pro743Leu) (1/26), c. 1525A>G(p.Thr509Ala) (1/26), and c. 1349C>T(p.Thr450Met) (1/26). Only 1 heterozygous variation was detected in 2 families. c. 2363C>T (p.Ser788Leu), c. 1832T>C (p.Leu611Pro) and c. 1525A>G (p.Thr509Ala) were not reported previously and predicted as "harmful" to the protein function. Conclusion The main type of ocular albinism is oculocutaneous albinism type Ⅱ in Liuzhou region, where the most common variations of the P gene were c. 803-3C>G and c. 1327G>A (p.Val443Ile). Above finding has enriched the variation spectrum of the P gene.

OBJECTIVE: To identify potential mutation in a child clinically diagnosed as Noonan syndrome and to provide genetic counseling and prenatal diagnosis for his family. METHODS: Genomic DNA was extracted from peripheral blood samples of the patient and his parents, and amniotic fluid was taken from the mother during the second trimester. Next generation sequencing (NGS) was used to screen potential mutations from genomic DNA. Suspected mutation was verified by Sanger sequencing. RESULTS: A heterozygous c.4A>G (p.Ser2Gly) mutation of the SHOC2 gene was identified in the patient but not among other family members including the fetus. CONCLUSION The Noonan syndrome is probably caused by the c.4A>G mutation of the SHOC2 gene. NGS is helpful for the diagnosis of complicated genetic diseases. SHOC2 gene mutation screening is recommended for patient suspected for Noonan syndrome.
Child ; Female ; Genetic Testing ; High-Throughput Nucleotide Sequencing ; Humans ; Intracellular Signaling Peptides and Proteins ; Mutation ; Noonan Syndrome ; Pregnancy ; Prenatal Diagnosis

OBJECTIVETo evaluate the clinical value of multicolor melting curve analysis(MMCA) for detecting genetic mutations in G6PD deficiency.

METHODSA 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.

RESULTSOne 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.

CONCLUSIONMulticolor 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.

Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Glucosephosphate Dehydrogenase ; genetics ; Humans ; Infant ; Infant, Newborn ; Male ; Mutation ; Polymerase Chain Reaction ; methods ; Sequence Analysis, DNA