| Objectives In the first of this study,using genetic diagnosis technology is necessary for help to find out the causes of hereditary deafness,so that people can take preventive measures and provide guidance in advance.In the second of this study,by collecting the medical history data,the audiological,the phenotype and genetic characteristic of a Chinese family with hearing loss were analyzed,and the possible gene mutation for this family were located.Methods In the first of this study,from September 2013 to March 2015,eight families with sensorineural hearing loss were selected.The peripheral blood was collected from the deaf profound and their members and DNA was extracted,followed by application of the second—generation sequencing method or Sanger sequencing.The second part is to select one deafness family for further investigation.First of all,by asking about the past medical history,the distribution of the disease were carried out from the family members with deafness.According to the genetic information,a pedigree diagram was drawn and the potential genetic models were explored.Second,the pathogenesis of partial patients were in-depth surveyed,and the related inspection data of these family members were performed,such as otolaryngological specialist examination,audiology examination,laboratory examination,imaging examination.In addition,some of the immediate relatives who were not ill were also examined accordingly.At last,the peripheral venous blood samples of the family numbers were extracted.Using the method of next-generation sequencing(NGS)and comparing the gained gene sequencing with the reference version GRCH37/hg19,we obtained possible new gene mutations of these family numbers and the new gene mutation loci was confirmed by Sanger sequencing.Results Part 1:Among the eight families,the profound from Family 1 was heterozygous MYH9 mutation,the father and their son are also the heterozygous MYH9 mutation;the profound from Family 2 was compound heterozygous USH2A mutation,and the parents were respectively heterozygous mutation of c.15427C>T and c.10312G>A;the profound from Family 3 was heterozygous OPA1 mutation with the mother of the same genotype;the heterozygous 12SrRNA mutation were found in the profound and offspring from Family 4,5 and 6;the profound from Family 7 was heterozygous CHD7 mutation;the profound from Family 8 was compound heterozygous SLC26A4 and POU4F3 mutation,his father was heterozygous mutation of SLC26A4 c.1079C>T mutation,his mother was heterozygous mutation of SLC26A4 c.1079C>T and POU4F3 c.9192A>G mutation;the profound from Family 9 was heterozygous MY03 A mutation,which originated from parents.Part 2:Based on the comprehensive genetic characteristics,clinical manifestations and audiological characteristics,it can be concluded that the affected members exhibited bilateral symmetry,progressive,late—onset autosomal dominant inheritance sensorineural hearing loss.T he hearing impairment mainly involved high frequency or all frequency.Combined with laboratory examinations and imaging examinations,deafness patients don’t show manifestations such as thrombocytopenia,cataracts,nephritis,and exclude intracranial spaceoccpuying lesion.It can be concluded that the family is a nonsyndromic hearing loss family.We take advantage of the second generation sequencing techlogy to find there suspicious heterozygous mutations(MYH9 C.314A>T,MY03A C.1324C>T,and TCIRG1 C.1801G>A).The phenotype of deafness in patients was essentially consistent with the phenotype of DFNA17.The mutation site of the gene was further confirmed by Sanger sequencing.Conclusion 1.The second generation sequencing method and Sanger sequencing method play important roles in the detection of deafness pathogenic genes and gene loci.Genetic diagnosis technology is of great significance for guiding the birth of hereditary deafness families and taking preventive measures.2.Preliminary molecular genetic analysis identifyed the cause of the Chinese family with non-syndromic autosomal dominant hereditary deafness,a new compound heterozygous mutation MYH9 gene:C.314 A>T(p.Y105F). |
