Newborn genetic screening for high risk deafness-associated mutations with a new Tetra-primer ARMS PCR kit
ABSTRACT Previous epidemiological studies indicate that GJB2, SLC26A4 or mtDNA 12S rRNA mutations were chiefly responsible for the hearing loss in children. A cost-effective method for screening deafness-associated mutations at early age is needed. This study aimed to develop a simple kit for screening of high risk deafness-associated mutations in newborns using tetra-primer amplification refractory mutation system PCR.
The screening kit was designed to detect high risk deafness-associated mutations (GJB2 c.235delC, SLC26A4 c.919-2A>G, mtDNA 12S rRNA mt.1555A>G and mt.1494C>T). The kit was able to amplify both wild-type and mutant alleles with a control fragment. The proposed method was conducted to genotype the above four deafness gene mutations in four PCR reactions. Each mutation was genotyped by a set of four primers, two allele-specific inner primers, and two common outer primers. A mismatch at the penultimate or antepenult nucleotide of the 3' terminus was introduced in order to maximize specificity. The 16 primers were used for the amplification of genomic DNA as a template. Amplified fragments were separated by electrophoresis. We designed and validated the kit with wild and mutant type DNA samples that had been previously been confirmed by Sanger sequencing. Then 1181 newborns were enrolled, and those samples with mutations were further validated with sequencing too.
Among 1181 newborns, 29 individuals had one or two mutant alleles, with the carrier rate being 2.46% (29/1181). For GJB2 c.235delC mutation, one case was homozygote and 12 cases were heterozygote carriers. For SLC26A4 c.919-2A>G mutation, 12 cases were heterozygotes carriers, and no homozygotes were found; for mtDNA 12S rRNA mt.1555A>G mutation, one case was identified; three cases of mtDNA 12S rRNA mt.1494C>T mutation were detected. All mutations were detected with high specificity. Mutation samples were confirmed via Sanger sequencing. No false positive was found.
A user-friendly screening kit for deafness-associated mutations was successfully developed. It provided rapid, reproducible, and cost-effective detection of deafness gene mutation without special equipment. The kit allowed the detection of the four high risk deafness-associated mutations with only 4 single tube PCR reactions. In the future, the kit could be applied to large population-based epidemiological studies for newborn hearing defects screening.
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ABSTRACT: GJB2 mutation is recognized as the prevalent causes of non-syndromic hearing loss (NSHL) worldwide. However, the mutation profiles of GJB2 are rarely reported in deafness probands of the assortative mating family. Therefore, this study aimed to characterize the frequencies of GJB2 mutations in probands with hearing loss in the assortative mating family in Hubei province, Central China. Genomic DNA was extracted from blood samples of 29 probands with hearing loss. The target fragments were amplified by polymerase chain reaction (PCR) and subjected to sequencing to identify sequence variations. None of 29 probands harbored homozygous mutation in GJB2, while GJB2 heterozygous mutations c.134G>A, c.139G>T, and a deletion c.235delC were identified in three probands, respectively. GJB2 mutations are rare in Chinese probands of assortative mating families. Screening for responsible genes other than GJB2 is necessary for NSHL in these probands.International journal of pediatric otorhinolaryngology 12/2013; 78(2). DOI:10.1016/j.ijporl.2013.11.013 · 1.32 Impact Factor
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ABSTRACT: Mutations in the GJB2 gene are the most common cause of congenital hearing loss in many populations. This study describes the development of a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based minisequencing assay, TheraTyper-GJB2, for the detection of c.35delG, c.167delT, and c.235delC mutations in the GJB2 gene. This assay was evaluated for analytic performance, including detection limit, interference, cross-reactivity, and precision, using GJB2 reference standards prepared by site-directed mutagenesis of a molecular clone. The detection limit was as low as 0.040 ng of human genomic DNA per PCR. No cross-reactivity with bacteria and viruses and no negative effects of increased levels of various potential interfering substances was observed. A precision test involving repetitive analysis of 2400 replicates showed 99.9% agreement (2397 of 2,400) with 99.8% (95% CI, 99.7%-99.8%) sensitivity and 100.0% (95% CI, 99.3%-100.0%) specificity. TheraTyper-GJB2 and direct sequencing assays showed 100% concordance for detecting mutations in 1,113 clinical specimens. Overall, TheraTyper-GJB2 showed comparable performance for detecting GJB2 mutations in reference and clinical samples with that of direct sequencing, and easier interpretation of results for analysis of a large quantity of samples. Therefore, the TheraTyper-GJB2 assay will be practically useful for the diagnosis of GJB2 mutations associated with congenital hearing loss with faster, cheaper, more reliable, and high-throughput capability.The Journal of molecular diagnostics: JMD 07/2014; DOI:10.1016/j.jmoldx.2014.04.006 · 3.96 Impact Factor