A novel method for detecting nine hotspot mutations of deafness genes in one tube

Deafness is a common sensory disorder. In China, approximately 70% of hereditary deafness originates from four common deafness-causing genes: GJB2, SLC26A4, GJB3, and MT-RNR1. A single-tube rapid detection method based on 2D-PCR technology was established for nine mutation sites in the aforementioned genes, and Sanger sequencing was used to verify its reliability and accuracy. The frequency of hotspot mutations in deafness genes was analysed in 116 deaf students. 2D-PCR identified 27 genotypes of nine loci according to the melting curve of the FAM, HEX, and Alexa568 fluorescence channels. Of the 116 deaf patients, 12.9% (15/116) carried SLC26A4 mutations, including c.919-2A > G and c.2168A > G (allele frequencies, 7.3% and 2.2%, respectively). The positivity rate (29.3%; 34/116) was highest for GJB2 (allele frequency, 15.9% for c.235delC, 6.0% for c.299_300delAT, and 2.6% for c.176-191del16). Sanger sequencing confirmed the consistency of results between the detection methods based on 2D-PCR and DNA sequencing. Common pathogenic mutations in patients with non-syndromic deafness in Changzhou were concentrated in GJB2 (c.235delC, c.299_300delAT, and c.176-191del16) and SLC26A4 (c.919-2A > G and c.2168 A > G). 2D-PCR is an effective method for accurately and rapidly identifying deafness-related genotypes using a single-tube reaction, and is superior to DNA sequencing, which has a high cost and long cycle.

Molecular Characteristics and Genetic Analysis of Extensively Drug-Resistant Isolates with different Tn3 Mobile Genetic Elements

Extensively drug-resistant (XDR) bacteria are the main caues for causing clinical infectious diseases. Our aim was to distinguish the present molecular epidemiological situation of XDR Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli isolates recovered from local hospitals in Changzhou. Antibiotic susceptibility and phenotypic analysis, multilocus sequence typing and Pulsed Field Gel Electrophoresis were performed to trace these isolates. Resistant phenotype and gene analysis from 29 XDR strains demonstrated that they mainly included TEM, CTX-M-1/2, OXA-48, and KPC products. A. baumannii strains belonged to sequence type (ST) ST224, and carrying the bla_CTX-M-2/TEM gene. The quinolone genes aac(6')-ib-cr and qnrB were carrying only in A. baumannii and E.coli. Three (2.3%) of these strains were found to contain the bla_NDM-1 or bla_NDM-5 gene. A new genotype of K. pneumoniae was found as ST2639. Epidemic characteristics of the XDR clones showed that antibiotic resistance genes distributed unevenly in different wards in Changzhou's local hospitals. With the sequencing of bla_NDM carrying isolates, the plasmids often carrying a highly conservative Tn3-relavent mobile genetic element. The especially coupled insert sequence ISKox3 may be a distinctive resistance gene transfer loci. The genotypic diversity variation of XDRs suggested that tracking and isolating the sources of antibiotic resistance especially MBL-encoding genes such as bla_NDM-will help manage the risk of infection by these XDRs.