| Congenital hearing loss is one of the most common birth defect. It's reported that the incidence of Congenital hearing loss is 1‰～3‰abroad. But in China the incidence varies from place to place, which is between 1.01‰～9.52‰. Seventy percent of patients have the manifestation of solitary dysaudia belonging to non-syndromic hearing impairment, which is hardly detected in early stage. Others presents with tardive or progressive dysaudia. In case we don't take effective measures such as early diagnosis, early intervention and early treatment, they will join in the potential deaf population, causing a greater burden on families and society. Previous Researches show that 50% of congenital deafness is caused by heredity,25% by environmental factors, the remaining 25% is not clear. Effective early prevention for patients with congenital hearing loss is the goal and drive for audiology researchers in the world. Along with the advance of newborn hearing screening in china for nearly ten more years, the warts and pimples are gradually exposed, the etiology of hearing loss becomes another research hot point, which promotes the project of newborn hearing combined with deafness gene genotyping in wider area in China. Gansu province is an important part of northwest of China with the features of broad area, different nationalities and unblanced economic development. It could be a classic documentation for the epidemiologic study on new born hearing combined with deafness gene genotyping in rural area. In this study 96711 infants who were born in Gansu province from September 30th 2009 to September 30th 2010 received universal newborn hearing initial screening, and concerned deafness genes were genotyped in 2384 infants.Part 1 Analysis on 96711 cases of newborn hearing screening in Gansu provinceNinety-six thousand seven hundred and eleven infants who were born in 76 counties or districts of Gansu province from September 30th 2009 to September 30th 2010 received universal newborn hearing initial screening using distortion product otoacoustic emission (DPOAE) before the age of three months. The infants who failed initial screening were checked again one month later. Follow-up and relevant assessments of the hearing were provided continually for those who failed both tests. Results show that about 247864 infants were born in this period, of which 96711 received newborn hearing initial screening, the coverage rate is 39.02%. Among 96711 infants, 81758 (84.54%) infants passed the initial test and 14953 (15.46%) failed. All infants were divided into two groups by high risk factors:N group(without high risk factors, normal newborn) and H group(with high risk factors). Chi-square tests show in the initial screening the pass rate of N group is significantly higher than the H group (χ2=4.7926, P=0.0286). When considering the gender, we found that in the initial screening the pass rate of female group is significantly higher than male group (χ2=41.0967, P<.0001). When the infants were divided into two groups by different delivery modes, we found in the initial screening the pass rate of cesarean section group is significantly higher than nature delivery group (χ2=4.5827, P=0.0323). Pairwise comparison by the chi-square tests of the initial screening pass rate among the four main peoples Han, Hui, Zang and Dongxiang, results show that Han is significantly higher than Hui(χ2=1095.0332, P <.0001), Hui is significantly lower than Zang(χ2=157.9922, P<.0001) and Dongxiang(χ2=7.0858, P=0.0078). Fourteen thousand nine hundred and fifty-three infants needed rescreening, however only 4689(31.36%) accepted rescreening on time, of which 4250(90.64%) passed and 439 (9.36%) failed. In the 76 counties or districts, Akesai and Lintao counties have the highest coverage rate. Chi-square tests show the pass rate is significantly different between the fourteen cities (χ2=2042.218, P<.0001). Pairwise comparison shows Tianshui and Jiuquan, Gannan and Tianshui, Wuwei and Tianshui, Gannan and Jiuquan, Wuwei and Gannan, Wuwei and Jiuquan, Jiuquan and Pingliang, Zhangye and Baiyin, Zhangye and Jinchang, Baiyin and Jinchang were not significantly different, other pairs were significantly different. Chi-square tests show the pass rate of Hexi district is significantly higher than Hedong district (χ2=121.7278,P<.0001).From the results above, we can make a conclusion that gender, people, high risk factors, delivery modes and geographical variation influence the pass rate of newborn hearing initial screening. In all, it is feasible to conduct universal hearing screening program in the rural areas using distortion product otoacoustic emission (DPOAE), however, the suitable model to perform the program is urgently needed to be set up in order to improve the accuracy and widen the scope of screening.Part 2 Deafness Genes Screening on 2384 newborns in Gansu corridor areaIn this study, SLC26A4, mtDNA 12SrRNA m.1494 and mtDNA 12SrRNA m.1555 were genotyped in 2384 infants who were born in Gansu corridor area from November 2009 to April 2010. Results show that 30 patients were detected with SLC26A4 919-2A>G monoallelic mutations, total mutations frequency is 12.58%o, while in Jiuquan city, Jinchang city, Zhangye city, Wuwei city the frequency is 0‰,0‰,13.37‰,13.38‰, respectively. Six patients were detected with mtDNA12rRNAm.1555A>G homogeneity mutation,2 patients were detected with mtDNA12rRNAm.1555A>G heterogeneity mutation, mtDNA12rRNAm.1494C>T were not detected in this population, total mutations frequency is 3.36%o(including homogeneity and heterogeneity mutation), while in Jiuquan city, Jinchang city, Zhangye city, Wuwei city the frequency is 0‰,0‰,2.81‰,4.87‰, respectively. In conclusion, the mutation frequency of SLC26A4 919-2A>G in relation to Large vestibular aqueduct syndrome is similar in Zhangye city and Wuwei city, but the frequency of mtDNA12rRNAm.1555A>G in relation to aminoglycoside antibiotic induced deafness in Wuwei city is far higher than other three cities.
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