Application of single-cell RNA-sequencing in ophthalmology / 眼科新进展

Single-cell RNA-sequencing (sc RNA-seq) is a new technique allowing the analysis of transcriptomes in individual cell for discovering specific cell type markers,identifying rare cell types and cellular subsets and revealing the different expression among cells.It is becoming an effective method for researching cellular heterogeneity of complex biological system.In recent years,this approach has been widely used in diverse fields of biology,including stem cell,neurobiology,tumor,immunology,microbiology.In addition,it is also applied in ocular research area.As modem molecular biology and bioinformatics develops,there are some commercial platforms emerging gradually with characteristics of high-throughput,low cost and high efficiency.In this review,we will describe some of the current experimental methods used for sc RNA-seq and discuss the merits and drawbacks,as well as summarize the application of this technique in ophthalmology.In the future,this technique may expand to more studies of ocular-associated diseases for the guidance of clinical diagnosis and therapy.

Characterization of two Chinese families with aminoglycoside-induced and nonsyndromic hearing loss both carrying a mitochondrial 12S rRNA 1494C>T mutation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of mitochondrial DNA(mtDNA) secondary mutations, haplotypes, GJB2 gene mutations on phenotype of 1494C>T mutation, and to study the molecular pathogenic mechanism of maternally transmitted aminoglycoside-induced and nonsyndromic hearing loss.</p><p><b>METHODS</b>Two Chinese Han pedigrees of maternally transmitted aminoglycoside induced and nonsyndromic hearing loss were collected. The two probands and their family members underwent clinical, genetic and molecular evaluations including audiological examinations and mutational analysis of mitochondrial genome and GJB2 gene.</p><p><b>RESULTS</b>Clinical evaluation revealed wide range of severity, age-at-onset and audiometric configuration of hearing impairment in matrilineal relatives in both families, for which the penetrance of hearing loss was respectively 42.9% and 28.6% when aminoglycoside-induced deafness was included. When the effect of aminoglycosides was excluded, the penetrances of hearing loss were 14.3% and 14.3%. Sequence analysis of mitochondrial genomes identified a known 12S rRNA 1494C>T mutation, in addition with distinct sets of mtDNA polymorphisms belonging to Eastern Asian haplogroups C4a1a and B4b1c, respectively.</p><p><b>CONCLUSION</b>Mitochondrial 12S rRNA 1494C>T mutation probably underlie the deafness in both families. Lack of significant mutation in the GJB2 gene ruled out involvement of GJB2 in the phenotypic expression. However, aminoglycosides and other nuclear modifier genes may still modify the phenotype of the 1494C>T mutation in these families. The B4b1c is a newly identified haplogroup in aminoglycoside-induced and nonsyndromic hearing loss family carrying the 1494C>T mutation. The 1494C>T mutation seems to have occurred sporadically through evolution.</p>

Mitochondrial 12S rRNA variants studies in 456 subjects with hearing loss in seven schools for deaf and mutes in Zhejiang province / 中华耳鼻咽喉头颈外科杂志

<p><b>OBJECTIVE</b>To investigate mutational spectrum and frequency of the mitochondrial 12S rRNA gene in Chinese subjects with aminoglycoside-induced and non-syndromic hearing loss.</p><p><b>METHODS</b>Total of 456 subjects with non-syndromic hearing loss were recruited from seven schools for deaf-mutes in Zhejiang province. Genomic DNA was extracted from the whole blood, and then the DNA fragment was amplified spanning the 12S rRNA gene, followed by sequencing and analyzed.</p><p><b>RESULTS</b>Thirty-one variants were identified by mutation analysis of 12S rRNA gene in these subjects. The frequency of the known 1555A > G mutation was 4.4% (20/456). Prevalence of other putative deafness-associated mutation at positions 961 and 1095 were 2.0% (9/456) and 0.7% (3/456) respectively. Furthermore, the 1027A > G, 1109T > C and 1431G > A variants conferred increased sensitivity to ototoxic drugs or non-syndromic deafness as they were absent in 449 Chinese controls and localized at highly conserved nucleotides of this 12S rRNA gene. Moreover, clinical data showed a wide range of age-of-onset, variety of severity and various audiometric configurations in subjects carrying the 1555A > G mutation.</p><p><b>CONCLUSIONS</b>Our data demonstrated that the mitochondrial 12S rRNA gene is the hot spot for mutations associated with aminoglycoside ototoxicity and non-syndromic hearing loss. Nuclear modifier genes, mitochondrial haplotypes and environmental factors might play a role in the phenotypic manifestation of these mutations.</p>