[Current status of newborn deafness gene screeningin parts of China]

Objective:To analyze the current status of newborn deafness gene screening from 2016 to 2017 in multiple regions of China, and to provide a reference for further promotion and application. Method:The "newborn deafness gene screening questionnaire" was sent to 41 institutions in eastern, central and western China after expert demonstration. The survey content included status of genetic screening, screening methods, the number of screenings, and the status of positive detections from January 1st, 2016 to December 31th, 2017. Each institution returned the questionnaire, the investigator conducted data verification and quality sampling. Finally, we performed analysis of screening methods and the positive detection rate of each gene on questionnaires with complete data. Result:Forty-one questionnaires were sent out and 41 were returned, the questionnaire return rate was 100%, in which 12 questionnaires were complete. Of the 41 institutions, 15 carried newborn deafness gene screening, with a rate of 36.59%（15/41）. The highest rate was in the east（72.22%, 13/18）, and the differences among the regions were statistically significant. As for the screening methods, among 12 questionnaires with complete data, 9 variants in 4 genes and 20 variants in 4 genes accounted for the highest proportion, both with the rate of 33.33%（4/12）, followed by 15 variants in 4 genes（25%, 3/12） and 5 variants in 3 genes（8.34%, 1/12）. A total of 340, 521 neonates were included in the study, and 17, 036 were positive for screening, with a positive rate of 5.00%. Among them, the single heterozygous mutation rate of GJB2 gene was 2.43%（8269/340, 521）, the biallele mutation rate was 0.02%（56/340, 521）,the single heterozygous mutation rate of SLC26A4 gene was 1.99%（6771/340, 521）, the biallele mutation rate was 0.01%（39/340, 521）,the single heterozygous mutation rate of GJB3 gene was 0.33%（1140/340, 521）, the mitochondrial 12SrRNA gene mutation rate was 0.22%（746/340, 521） and the double-gene heterozygous mutation rate was 0.004%（15/340, 521）. Conclusion:From 2016 to 2017, the newborn deafness gene screening is more extensive in the eastern region of China than in the central and western regions. In institutions that have carried out deafness gene screening, 9 variants in 4 genes and 20 variants in 4 genes are widely used; the GJB2 gene and SLC26A4 gene mutations are the most common. The results could provide references for areas where deafness gene screening is about to be performed.

[Analysis of genotypes and hearing phenotypes of mutation infants with deafness]

Objective:The aim of this study is to explore the genotype and hearing phenotype of deaf infants with mutation of GJB2 gene. Method:Subjects were 121 infants with GJB2 gene mutations who were treated in the Children's Hearing Diagnosis Center of Beijing Tongren hospital. All subjects were accepted to undertake the universal newborns hearing screening（UNHS） and series of objective audiometry, including auditory brainstem response, distortion product otoacoustic emission, auditory steady-state response and other audiological tests. All subjects were screened for nine pathogenic variants in four genes or all exons of the GJB2 gene, and then were diagnosed as infants with GJB2 gene mutations. Initially, analyzing their genotypes and hearing phenotypes generally. Then, the subjects were divided into two groups according to the genotypes: T/T group（truncated/truncated mutations, 89 cases） and T/NT group（truncated/non-truncated mutations, 32 cases）. Chi-square test was used to analyze the results of UNHS, hearing degree, audiogram patterns and symmetry/asymmetry of binaural hearing phenotype. Eventually, analyzing the results of UNHS. Result:The most common truncated mutation was c.235delC（64.88%, 157/242） and the most common non-truncated mutation was c.109G>A（11.16%, 27/242）. The homozygous mutation of c.235delC/c.235delC was the dominant in T/T group（38.84%, 47/121）, and the compound heterozygous mutation of c.235delC/c.109G>A was the dominant in T/NT group（18.18%, 22/121）. 81.82%（99/121） of subjects failed in UNHS, including 74.38%（90/121） with bilateral reference, 7.44%（9/121） with a single pass. The refer rate of UNHS of group T/T and T/NT were 86.52%（77/89） and 68.75%, respectively. There was a statistically significant difference between the two groups（P<0.05）. 85.95%（104/121） of subjects were diagnosed as hearing loss and 14.05%（17/121） of subjects were diagnosed as normal hearing. The degree of hearing loss: profound, severe, moderate and mild were 31.40%（38/121）, 19.01%（23/121）, 24.79%（30/121） and 10.74%（13/121）, respectively. There was no subjects with normal hearing in T/T group and individuals with severe and profound hearing loss accounted for the highest proportion（65.17%, 58/89）, while in T/NT group, normal hearing accounted for 53.13%（17/32） and mild and moderate hearing loss accounted for the highest proportion（37.5%, 12/32）. There was statistically significant difference between the two groups（P<0.05）. Of 104 patients（208 ears） with hearing loss, the audiogram patterns: flat, descending, ascending, residual, Valley and other types were 49.03%（102/208）, 12.02%（25/208）, 8.65%（18/208）, 7.69%（16/204）, 3.36%（7/204） and 19.23%（40/204）, respectively. The two most common types in T/T group were flat（47.19%, 84/178） and other types（20.22%, 36/178）, while in T/NT group were flat（60.00%, 18/30） and ascending（20.00%, 6/30）. There was statistically significant difference between the two groups（P<0.05）. There were 50 cases（48.07%） with symmetrical hearing phenotype and 54 cases（51.93%） with asymmetrical hearing phenotype. Asymmetry was predominant in T/T group（53.93%, 48/89）, and symmetry was predominant in T/NT group（60.00%, 9/15）. There was no statistically significant difference between the two groups（P>0.05）. Conclusion:In this study, c.235delC/c.235delC homozygous mutation was dominant in T/T group and c.235delC/c.109G>A heterozygous mutation was dominant in T/NT Group. The hearing phenotypes in T/T group were mostly bilateral asymmetric severe hearing loss, and those in T/NT Group were bilateral symmetric mild to moderate hearing loss, special attention should be paid to the audiological characteristics of different genotypes.