Prognostic role of C-reactive protein in patients with nasopharyngeal carcinoma: A meta-analysis and literature review.

BACKGROUND: C-reactive protein (CRP) has been shown to be associated with several tumors. However, its association with nasopharyngeal carcinoma (NPC) is not well characterized. We performed a literature review and meta-analysis to assess the prognostic relevance of elevated CRP levels in patients with NPC. METHODS: A literature search for relevant studies was performed on PubMed (Medline), the Cochrane Library, and Web of Science databases. Hazard ratios (95% confidence intervals) were calculated to assess the association between elevated CRP levels and survival outcomes. RESULTS: Five studies with a combined study population of 5215 patients with NPC were included. Pooled hazard ratios for overall survival and distant metastasis-free survival were 1.84 (95% CI = 1.57-2.17) and 1.81 (95% CI = 1.53-2.14), respectively. Subgroup analyses showed that types of indicators and treatment before inclusion had no significant impact on the observed association. CONCLUSION: Elevated serum CRP levels in patients with NPC were associated with worse prognosis.

HSP47 is associated with the prognosis of laryngeal squamous cell carcinoma by inhibiting cell viability and invasion and promoting apoptosis.

Heat shock protein 47 (HSP47) is a 47 kDa collagen binding protein that has a close relationship with the development and progression of tumours. However, little is known concerning the expression profile of HSP47 in laryngeal squamous cell carcinoma (LSCC) patients and there is still insufficient data concerning the underlying mechanisms. The aim of the present study was to explore the expression of HSP47 in LSCC and provide an overview of its association with tumourigenicity and clinical prognosis. The expression of HSP47 in LSCC and adjacent non-cancerous laryngeal tissues was assessed via western blotting and immunohistochemical studies. The prognostic significance of HSP47 expression was analysed using a Kaplan-Meier survival curve. To investigate the influence of HSP47 on the viability, invasion and apoptosis of a LSCC cell line, we performed an in vitro analysis with plasmid vectors and small interfering RNA (siRNA). Our results showed that HSP47 protein expression in the LSCC tissues was markedly decreased compared to that noted in the adjacent non-cancerous tissues, and low expression of HSP47 was correlated with poor prognosis in LSCC patients. Upregulation of HSP47 via plasmid vectors inhibited the proliferation, reduced the invasive ability, increased the sensitivity to cisplatin chemotherapy, promoted apoptosis, and induced the G1 phase arrest of LSCC cells in vitro. The expression of apoptosis-regulating proteins was also altered when HSP47 was upregulated, involving increased expression of cleaved caspase-7/-8/-9, PARP, and Bax and decreased expression of Bcl-2. Our present data suggest that HSP47 is an important prognostic factor and an attractive therapeutic target in LSCC due to its influence on the biological behaviour of LSCC cells.

Clinical relationship between auditory neuropathy and nervous system diseases.

OBJECTIVE: To explore the clinical relationship between auditory neuropathy (AN) and nervous system diseases. METHODS: A total of 134 AN patients who were treated in our hospital from December 2011 to April 2016 were selected. Then 120 cases (240 ears) with complete data of pure tone audiometry and acoustic immittance test were selected as an AN1 group, which was compared with 30 patients (49 ears) with general sensorineural hearing loss (SHL) in regard to the results of pure tone audiometry and acoustic immittance test. On the other hand, 79 cases (158 ears) of the 134 patients with complete data of DP otoacoustic emission test were selected as an AN2 group, which was compared with 30 normal subjects (60 ears) regarding the results of DP otoacoustic emission test. RESULTS: Increases in the pure-tone hearing threshold by air conduction of AN1 group significantly exceeded those of SHL group at 0.125 and 0.25 kHz (low frequency) (P<0.05). The former group had significantly lower values at 1.0, 2.0 kHz (moderate frequency) and 4.0, 8.0 kHz (high frequency) (P<0.05). Of 134 patients, 14 (19 ears) had evoked V wave upon auditory brainstem response, whereas no waves after I wave were evoked in other tested ears. Distortion product (DP) otoacoustic emissions could all be evoked. AN2 group had significantly higher amplitudes of DP-gram than those of normal control group at 0.5 and 0.7 kHz (low frequency) (P<0.05). Except for three cases of unsteady walking and 10 of dizziness, others did not suffer from typical symptoms of vertigo attack. As to caloric test-induced electronystagmograms, there were 30 bilaterally normal cases (75.0%), one case of left-side semicircular canal paresis (25%) and nine cases of bilateral semicircular canal paresis (22.5%). Four patients with other nervous system diseases were complicated with AN. Other nervous system disorders included three cases of optic nerve atrophy and 7 of lower limb nerve damage. CONCLUSION: According to characteristic hearing dysfunction, AN may occur in the afferent pathway of acoustic nerve, probably accompanied by the pathological changes of efferent nerve in the olivocochlear system inside the brainstem.

The Lung Function Impairment in Non-Atopic Patients With Chronic Rhinosinusitis and Its Correlation Analysis.

OBJECTIVES: Chronic rhinosinusitis (CRS) is common disease in otorhinolaryngology and will lead to lower airway abnormality. However, the only lung function in CRS patients and associated factors have not been much studied. METHODS: One hundred patients with CRS with nasal polyps (CRSwNP group), 40 patients with CRS without nasal polyps (CRSsNP group), and 100 patients without CRS were enrolled. The difference in lung function was compared. Meanwhile, CRSwNP and CRSsNP group were required to undergo a bronchial provocation or dilation test. Additionally, subjective and objective outcomes were measured by the visual analogue scale (VAS), 20-item Sino-Nasal Outcome Test (SNOT-20), Lund-Mackay score, Lund-Kennedy endoscopic score. The correlation and regression methods were used to analyze the relationship between their lung function and the above parameters. RESULTS: The forced expiratory volume in 1 second (FEV1) and forced expiratory flow between 25% and 75% of forced vital capacity (FEF25-75) of CRSwNP group were significantly lower than other groups (P<0.05). On peak expiratory flow, there was no difference between three groups. In CRSwNP group, FEV1 was negatively correlated with peripheral blood eosinophil count (PBEC) and duration of disease (r=-0.348, P=0.013 and r=-0.344, P=0.014, respectively), FEF25-75 negatively with VAS, SNOT-20 (r=-0.490, P=0.028 and r=-0.478, P=0.033, respectively) in CRSsNP group. The incidence of positive bronchial provocation and dilation test was lower in CRSwNP group (10% and 0%, respectively), with both 0% in CRSsNP group. The multiple linear regression analysis indicated that change ratio of FEV1 before and after bronchial provocation or dilation test were correlated with PBEC in CRSwNP group (ß=0.403, P=0.006). CONCLUSION: CRS leading to impaired maximum ventilation and small airway is associated with the existence of nasal polyp. Lung function impairments can be reflected by PBEC, duration, VAS, and SNOT-20. In CRSwNP patients, PBEC is independent predictor of FEV1 change ratio.

Downregulation of cancer stem cell properties via mTOR signaling pathway inhibition by rapamycin in nasopharyngeal carcinoma.

Rapamycin, a mammalian target of rapamycin (mTOR) signaling inhibitor, inhibits cancer cell proliferation and tumor formation, including in nasopharyngeal carcinoma (NPC), which we proved in a previous study. However, whether rapamycin affects cancer stem cells (CSCs) is unclear. In examining samples of NPCs, we found regions of CD44-positive cancer cells co-expressing the stem cell biomarker OCT4, suggesting the presence of CSCs. Following this, we used double-label immunohistochemistry to identify whether the mTOR signaling pathway was activated in CD44-positive CSCs in NPCs. We used a CCK-8 assay and western blotting to explore whether the stem cell biomarkers CD44 and SOX2 and the invasion protein MMP-2 could be suppressed by treatment with rapamycin in cultured primary NPC cells and secondary tumors in BALB/c nude mice. Interestingly, we found that rapamycin inhibited mTOR signaling in addition to simultaneously downregulating the expression of CD44, SOX2 and MMP-2 and that it affected cell growth and tumor size and weight both in vitro and in vivo. Collectively, we confirmed for the first time that CSC properties are reduced and invasion potential is restrained in response to mTOR signaling inhibition in NPC. This evidence indicates that the targeted inhibition of CSC properties may provide a novel strategy to treat cancer.

[Application of the discharge, inflammation, polyps/edema (DIP) endoscopic scoring system in patients with chronic rhinosinusitis].

OBJECTIVE: To validate the discharge, inflammation, polyps/edema (DIP) scoring system for the assessment of endoscopic sinus surgery (ESS) outcomes in patients with chronic rhinosinusitis (CRS). METHODS: Thirty patients with CRS were included in this prospective study. All patients were evaluated before and 2 months after surgery. Baseline measures and postoperative outcomes were evaluated using sino-nasal outcome test-20 (SNOT-20), visual analogue scale (VAS) symptom score and Lund-Mackay CT score (in baseline only). All endoscopic videos were recorded before surgery and in the end of follow-up. All videos were scored blindly by two rhinologistis using the DIP and Lund-Kennedy system for investigating the inter-rater and test-retest reliability, as well as the correlations with the existing subjective and objective scoring systems.SPSS17.0 software was used to analyze the data. RESULTS: The average scores of VAS, SNOT-20, Lund-Kennedy, and DIP before and after surgery were listed below. Baseline, 29.73 ± 13.05, 24.43 ± 13.76, 7.70 ± 3.25 and 32.67 ± 13.48. Post-surgical, 13.60 ± 8.67, 10.40 ± 7.45, 5.03 ± 2.04 and 16.97 ± 8.37. All scores were declined significantly from baseline (t value were 7.43, 6.49, 6.88 and 10.93, all P < 0.001). The DIP system showed a higher inter-rater and rest-rest reliability than Lund-Kennedy system (interclass coefficient,ICC > 0.75). The Pearson analysis revealed that VAS scores were significantly correlated with SNOT-20 scores both in baseline and post-surgical assessments (r = 0.518 6, P = 0.003, and r = 0.546 7, P = 0.000). Before surgery, Lund-Kennedy scores were significantly correlated with DIP and Lund-Mackay CT scores (r = 0.937 5, P = 0.000 and r = 0.748 0, P = 0.000). DIP scores were significantly correlated with Lund-Mackay CT scores (r = 0.712 2, P = 0.000). After surgery,DIP scores were significantly correlated with Lund-Kennedy scores (r = 0.869 6, P = 0.000). But there were no significant correlations between subjective scores (VAS and SNOT-20) and objective scores (Lund-Kennedy, DIP and Lund-Mackay CT), (all P > 0.05). CONCLUSIONS: The DIP scoring system shows substantial inter-rater and test-retest reliability.It is also significantly correlated with existing objective scoring parameters. It is suitable and reliable to use.

[Low expression of succinate dehydrogenase subunit B in locally recurrent nasopharyngeal carcinoma and implication for prognosis].

OBJECTIVE: To study the expression of succinate dehydrogenase subunit B (SDHB) in the tissues of locally recurrent nasopharyngeal carcinoma (rNPC) and the correlation with the clinicopathological factors and prognosis of rNPC. METHODS: Immunohistochemistry was used to detect the expression of SDHB in the tissues of primary and locally recurrent nasopharyngeal carcinoma. The relationship between SDHB expression and clinicopathological features was analyzed using the Chi-square test, and Kaplan-Meier method and Log-rank test were used for survival analysis. The independent prognostic factors of rNPC were analyzed by Cox regression model. RESULTS: Low SDHB expression was showed in 76.5% (39/51) of the patients with rNPC, significantly higher than 57.1% (24/42) of primary nasopharyngeal carcinoma (χ(2) = 4.098, P < 0.05). Low expression of SDHB strongly was correlated with T classification, clinical stage and cranial nerve palsy. Patients with low SDHB expression had a shorter survival time and a lower 3 or 5 year survival rate compared to the patients with high SDHB expression. Multivariate analysis showed that low SDHB expression was an independent predictor for overall survival of patients with rNPC (P < 0.05). CONCLUSION: The low SDHB expression is an independent indicator for poor prognosis of rNPC and may play an important role in the recurrence of rNPC.

Influence of recombinant lentiviral vector encoding miR-15a/16-1 in biological features of human nasopharyngeal carcinoma CNE-2Z cells.

MicroRNAs can function as tumor suppressor miRNAs. Bcl-2 is an antiapoptotic gene overexpressed in many tumors, including nasopharyngeal carcinoma (NPC). It is reported that microRNA-15a (miR-15a) and microRNA-16-1 (miR-16-1) could act as bcl-2 inhibitors. To investigate their effects on NPC, the authors used recombinant lentiviral vector to upregulate the expression of miR-15a/16-1 in NPC CNE-2Z cells. The authors divided cells into the control group, transfection group, radiotherapy group, and transfection-radiotherapy group. In this experiment, reverse transcription-quantitative polymerase chain reaction was used to detect the expression of miR-15a/16-1 and bcl-2 mRNA. Cell proliferation was analyzed by MTT assay. Flow cytometry was used to measure cell apoptosis. Radiosensitivity was measured using colony-forming experiment. The protein expression of bcl-2 was measured by western blot, the activation levels of caspase were detected by a spectrophotometric method. After transfection, cell proliferation was inhibited, while the apoptosis rate and radiosensitivity were increased. In addition, the activation of caspase-2 and caspase-3 was aggrandized correspondingly. Although the expression levels of bcl-2 mRNA in each group had no difference, the protein expression of bcl-2 was downregulated. These results suggested that miR-15a/16-1 could inhibit cell proliferation and increase the apoptosis and radiosensitivity of CNE-2 cells, by regulating the bcl-2 gene at post-transcriptional level and by increasing the activation of caspase-2 and caspase-3.

Identification of novel tumor suppressor genes down-regulated in recurrent nasopharyngeal cancer by DNA microarray.

The nasopharyngeal cancer is a common cancer among southern Chinese. In order to better understand molecular mechanism of recurrent nasopharyngeal cancer (rNPC), we used DNA microarray to identify down-regulated tumor suppressed genes (TSGs) in rNPC, and bioinformatics to analyze their chromosomal localizations and molecular functions. Eight non-recurrent nasopharyngeal cancer (nNPC) and six rNPC tissue samples were selected, and Affymetrix Gene1.0 ST chips were used to construct the expression profiling of each tissue sample. Identify the down-regulated TSGs in rNPC by comparing expression profiling data of two type tissue samples. A total of five TSGs were identified to be down-regulated in rNPC. These five TSGs include SERPINF1, TPD52L1, FBLN1, RASSF6, and S100A2, and Signal Log Ratio were -2.2, -2.3, -3.5, -3.9 and -6.9 respectively. Chromosomal localization analysis showed that S100A2, RASSF6, TPD52L1, SERPINF1, and FBLN1 were located on chromosomes 1q, 4q, 6q, 17p and 22q, respectively. Functional analysis showed that SERPINF1 and TPD52L1 belonged to enzyme activity genes, S100A2 and FBLN1 belonged to calcium ion binding genes, RASSF6 belong to protein binding genes. Five TSGs likely to be the candidate TSGs involved in rNPC, and may play important roles in occurrence of rNPC. Chromosomes 1q, 4q, 6q, 17p and 22q may be considered as important region for screening TSGs that may relevant to rNPC. Those genes and chromosomal region need to be further studied.

[Influence of recombinant lentiviral vector encoding miR-15a/16-1 in biological features of human nasopharyngeal carcinoma CNE-2Z cells].

OBJECTIVE: To study the influence of recombinant lentiviral vector encoding miR-15a/16-1 on biological features of human nasopharyngeal carcinoma CNE-2Z cells and underlying mechanisms. METHODS: GFP-positive CNE-2Z cells transfected with recombinant lentiviral vector were selected. The experiment was divided into control group, transfected group, radiotherapy group, transfected-radiotherapy group. Cell proliferation was analyzed by MTT. Apoptosis was detected by flow cytometry. Radiotherapy sensitivity of the cells in control group and transfected group was evaluated by colony forming experiment. The expressions of miR-15a, miR-16-1 and bcl-2 mRNA were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The expression of bcl-2 protein was detected by Western blot. The activation of Caspase-2 and Caspase-3 was evaluated by spectrophotometry. RESULTS: Relative expression quantities of miR-15a and miR-16-1 in infected group were 524.80 ± 40.79 (t = 494.611, P = 0.000) and 466.11 ± 40.96 (t = 386.8, P = 0.000), respectively. The proliferation of the cells in transfected-radiotherapy group was the most obvious, followed by the cells in radiotherapy group and transfected group (F = 424.3, P = 0.000). The apoptosis rates of control group, transfected group, radiotherapy group and transfected-radiotherapy group were (2.2 ± 1.4)%, (9.6 ± 0.8)%, (2.9 ± 1.1)%, and (18.6 ± 0.7)% respectively(F = 158.5, P = 0.000). Clonogenic assay showed that the values of SF2, Do (1.473) and Dq (1.581) in transfected group were lower than those in control group. The relative expression levels of bcl-2 mRNA in transfected group, radiotherapy group, and transfected-radiotherapy group had no significant difference (P > 0.05). Decrease in the expression of bcl-2 protein in transfected-radiotherapy group was most significantly, followed by that in transfected group. The percentages of activated Caspase-2 in control group, radiotherapy group, transfected group and transfected -radiotherapy group were 0.12 ± 0.01, 0.24 ± 0.04, 0.35 ± 0.02, and 0.44 ± 0.04, respectively (F = 115.500, P = 0.000). The percentages of activated Caspase-3 in the groups were 0.13 ± 0.01, 0.27 ± 0.01, 0.43 ± 0.02, and 0.83 ± 0.06, respectively (F = 439.921, P = 0.000). CONCLUSIONS: Recombinant lentiviral vector LV-miR15a/16-1 could improve the expression of miR-15a and miR-16-1 in CNE-2Z cells, inhibit the proliferation of CNE-2Z cells, promote apoptosis and enhance the sensitivity of the cells to radiotherapy probably by inhibiting bcl-2 expression, activating Caspase-2 and Caspase-3.

[Clinical study and survival analysis of combined modality therapies for advanced hypopharyngeal carcinoma].

OBJECTIVE: To evaluate the efficacy of combined modality therapy for advanced hypopharyngeal carcinoma in order to improve the curative effect of hypopharyngeal carcinoma. METHOD: Seventy-six male patients with the stage III - IV hypopharyngeal carcinoma were treated with postoperative combined modality. Of all the 76 cases, 44 were treated with postoperative radiotherapy, and the other 32 treated with chemoradiotherapy concurrently. RESULT: Kaplan Meier analysis indicated that the overall 5 survival rates of patients treated with postoperative radiotherapy was 25.9%, and that of patients treated with postoperative chemoradiotherapy was 27.8%. There was no significant difference between the two groups (P>0.05). Three and five years relapse-free survival rates of the patients treated with postoperative radiotherapy were 36.0%, 22.5%, and those of the patients treated with postoperative chemoradiotherapy were 68.0%, 45.3%. Significant difference was calculated between the two groups (P<0.05). According to the NCI CTC3.0 criteria, the toxicities on grade 3 or above of the two groups showed no significant difference (P>0.05). CONCLUSION: For advanced hypopharyngeal carcinoma, postoperative chemoradiotherapy yielded satisfactory relapse free survival and laryngeal function preservation rate which was superior to that of postoperative radiotherapy. Also the treatment toxicities were not increased.

Ectopic intratracheal thyroid.

Ectopic intratracheal thyroid (EITT) is a rare abnormality, with few cases reported in the literature. We describe a case of a 36-year-old woman with dyspnea due to EITT. We also discuss the epidemiology, etiologies, presentation, diagnosis, and management of EITT. Because EITT is a rare cause of airway obstruction, we hope to remind the clinician of it by presenting this case.

[Identification of differentially expressed genes in recurrent nasopharyngeal carcinoma and analysis of their chromosomal location].

OBJECTIVE: To identify differentially expressed genes in recurrent nasopharyngeal carcinoma (rNPC) by DNA microarrays, and analyze chromosomal localizations and molecular function by bioinformatics. METHODS: The primary nasopharyngeal carcinoma (pNPC) tissue samples and rNPC tissue samples were selected, and Affymetrix Gene1.0 ST gene chips were used to identify differential expressed genes in rNPC, and the bioinformatics was used to analyze their chromosomal localizations as well as molecular functions. RESULTS: A total of 44 genes were identified to be differential expressed in rNPC. Thirty-six genes were down regulated, 8 genes were up regulated. Functional classification of down-regulation genes showed that most genes (10 genes, 27.8%) belonged to the enzyme activity genes, followed by calcium ion binding genes (7 genes, 19.4%), protein binding genes (5 genes, 13.9%), receptor activity genes (4 genes, 11.1%), ATP binding genes (2 genes, 5.6%), transcription factor genes (2 genes, 5.6%), extracellular matrix binding and growth factor binding have 1 gene respectively (each accounted for 2.8%). In addition, the functions of 4 genes (11.1%) were unknown. Functional classification of up-regulation genes showed most genes (3 genes, 37.5%) were unknown, followed enzyme activity genes (2 genes, 25.0%), receptor activity, calcium ion binding and voltage-gated ion channel activity genes have 1 genes respectively (each accounted for 12.5%). These genes were localized randomly on the most the chromosomes, with a majority of them localized on chromosomes 1, 17. Chromosome 1 contained the most differentially expressed genes (10, 22.7%), followed by chromosomes 17 (5, 11.3%). CONCLUSIONS: The differential expressed genes in rNPC were supposed to be randomly distributed on most chromosomes, but the majorities were found on chromosomes 1, 17. Abnormality in three groups of genes, including in enzyme activity, calcium ion binding and protein binding associate genes, might play important roles in rNPC. Those genes need to be further studied.

Mitochondrial 12S rRNA variants in 1642 Han Chinese pediatric subjects with aminoglycoside-induced and nonsyndromic hearing loss.

In this report, we investigated the frequency and spectrum of mitochondrial 12S rRNA variants in a large cohort of 1642 Han Chinese pediatric subjects with aminoglycoside-induced and nonsyndromic hearing loss. Mutational analysis of 12S rRNA gene in these subjects identified 68 (54 known and 14 novel) variants. The frequencies of known 1555A>G and 1494C>T mutations were 3.96% and 0.18%, respectively, in this cohort with nonsyndromic and aminoglycoside-induced hearing loss. Prevalence of other putative deafness-associated mutation at positions 1095 and 961 were 0.61% and 1.7% in this cohort, respectively. Furthermore, the 745A>G, 792C>T, 801A>G, 839A>G, 856A>G, 1027A>G, 1192C>T, 1192C>A, 1310C>T, 1331A>G, 1374A>G and 1452T>C variants conferred increased sensitivity to ototoxic drugs or nonsyndromic deafness as they were absent in 449 Chinese controls and localized at highly conserved nucleotides of this rRNA. However, other variants appeared to be polymorphisms. Moreover, 65 Chinese subjects carrying the 1555A>G mutation exhibited bilateral and sensorineural hearing loss. A wide range of severity, age-of-onset and audiometric configuration was observed among these subjects. In particular, the sloping and flat-shaped patterns were the common audiograms in individuals carrying the 1555A>G mutation. The phenotypic variability in subjects carrying these 12S rRNA mutations indicated the involvement of nuclear modifier genes, mitochondrial haplotypes, epigenetic and environmental factors in the phenotypic manifestation of these mutations. Therefore, our data demonstrated that mitochondrial 12S rRNA is the hot spot for mutations associated with aminoglycoside ototoxicity.

[Analysis of the factors affecting the operational therapeutic efficacy for rhinosinusitis].

OBJECTIVE: To investigate the factors influence in the operational therapeutic efficacy for sinusitis. METHOD: Logistic regression analysis was performed for sex, age, clinical stage of sinusitis, used nasal decongestant preparation, recurrence of sinus surgery, allergic rhinitis, extensive postoperative treatments in 210 patients. RESULT: Age, used nasal decongestant preparation, recurrence of sinus surgery, allergic rhinitis, extensive postoperative treatments were the important factors influenced the operation therapeutic efficacy. CONCLUSION: Independent prognostic factors for patients with sinusitis after endoscopic sinus surgery are age, used nasal decongestant preparation, recurrence of sinus surgery, allergic rhinitis, extensive postoperative treatments. What's more, extensive postoperative treatments are one of the important factors to improve the operational therapeutic efficacy for chronic rhinosinusitis.

The ND4 G11696A mutation may influence the phenotypic manifestation of the deafness-associated 12S rRNA A1555G mutation in a four-generation Chinese family.

We report here the clinical, genetic and molecular characterization of a large Han Chinese family with aminoglycoside-induced and nonsyndromic hearing loss. The penetrance of hearing loss (affected matrilineal relatives/total matrilineal relatives) in this pedigree was 53%, when aminoglycoside-induced deafness was included. When the effect of aminoglycosides was excluded, the penetrance of hearing loss in this pedigree was 42%. These matrilineal relatives exhibited a wide range of severity of hearing loss, varying from profound to normal hearing. Furthermore, these affected matrilineal relatives shared some common features: bilateral hearing loss of high frequencies and symmetries. Sequence analysis of mitochondrial DNA (mtDNA) in the pedigree identified the homoplasmic 12S rRNA A1555G mutation and other 35 variants belonging to Eastern Asian haplogroup D4. Of these, the V313I (G11696A) mutation in ND4 was associated with vision loss. However, the extremely low penetrance of visual loss, and the mild biochemical defect and the presence of one/167 Chinese controls indicted that the G11696A mutation is itself not sufficient to produce a clinical phenotype. Thus, the G11696A mutation may act in synergy with the primary deafness-associated 12S rRNA A1555G mutation in this Chinese family, thereby increasing the penetrance and expressivity of hearing loss in this Chinese pedigree.

Maternally inherited aminoglycoside-induced and nonsyndromic hearing loss is associated with the 12S rRNA C1494T mutation in three Han Chinese pedigrees.

We report here the clinical, genetic and molecular characterization of three Han Chinese pedigrees with maternally transmitted aminoglycoside-induced and nonsyndromic bilateral hearing loss. Clinical evaluation revealed the wide range of severity, age-at-onset and audiometric configuration of hearing impairment in matrilineal relatives in these families. The penetrances of hearing loss in these pedigrees were 28%, 20%, and 15%, with an average of 21%, when aminoglycoside-induced deafness was included. When the effect of aminoglycosides was excluded, the penetrances of hearing loss in these seven pedigrees were 21%, 13% and 8%, with an average of 14%. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the presence of the deafness-associated 12S rRNA C1494T mutation, in addition to distinct sets of mtDNA polymorphism belonging to Eastern Asian haplogroups F1a1, F1a1 and D5a2, respectively. This suggested that the C1494T mutation occurred sporadically and multiplied through evolution of the mtDNA. The absence of functionally significant mutations in tRNA and rRNAs or secondary LHON mutations in their mtDNA suggests that these mtDNA haplogroup-specific variants may not play an important role in the phenotypic expression of the C1494T mutation in those Chinese families. In addition, the lack of significant mutation in the GJB2 gene ruled out the possible involvement of GJB2 in the phenotypic expression of the C1494T mutation in those affected subjects. However, aminoglycosides and other nuclear modifier genes play a modifying role in the phenotypic manifestation of the C1494T mutation in these Chinese families.

Mitochondrial tRNASer(UCN) gene is the hot spot for mutations associated with aminoglycoside-induced and non-syndromic hearing loss.

Mutations in mitochondrial DNA is one of the important causes of hearing loss. Here, we performed a mutational screening of tRNA(Ser(UCN)) gene in 1542 Chinese subjects with hearing loss. One subject and five subjects carried tRNA(Ser(UCN)) A7445C and G7444A mutations, respectively, while two subjects harbored both G7444A and 12S rRNA A1555G mutations. Clinical evaluation revealed the variable phenotype of bilateral hearing impairment including severity and audiometric configuration in these subjects. Six pedigrees carrying only G7444A or A7445C mutation exhibited extremely low penetrance of hearing loss, while two families carrying both G7444A and A1555G mutations displayed high penetrance of hearing loss. Of 94 matrilineal relatives in these families, eight subjects suffered from aminoglycoside-induced hearing loss, while seven hearing-impaired subjects did not have a history of exposure to aminoglycosides. Those suggest that G7444A and A7445C mutations themselves are insufficient to produce a clinical phenotype and aminoglycosides are the major modifier factors for the development of deafness in these Chinese families. The combination of A1555G and G7444A mutations increased deafness expression. These observations provide an additional evidence for the early diction and prevention of deafness at the high risk populations carrying these mitochondrial DNA mutations.

Very low penetrance of hearing loss in seven Han Chinese pedigrees carrying the deafness-associated 12S rRNA A1555G mutation.

Mutations in mitochondrial DNA (mtDNA) have been found to be associated with sensorineural hearing loss. We report here the clinical, genetic and molecular characterizations of seven Han Chinese pedigrees with aminoglycoside-induced and nonsyndromic bilateral hearing loss. Clinical evaluation revealed the variable phenotype of hearing impairment including severity, age-at-onset and audiometric configuration in these subjects. The penetrance of hearing loss in these pedigrees ranged from 3% to 29%, with an average of 13.6%, when aminoglycoside-induced deafness was included. When the effect of aminoglycosides was excluded, the penetrances of hearing loss in these seven pedigrees varied from 0% to 17%, with an average of 5.3%. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the presence of the deafness-associated 12S rRNA A1555G mutation, in addition to distinct sets of mtDNA polymorphism belonging to East Asian haplogroups B4, D4, D5 and F1, respectively. This suggested that the A1555G mutation occurred sporadically and multiplied through evolution of the mtDNA in China. Despite the presence of several evolutionary conservative variants in protein-encoding genes, there was the absence of functionally significant mutations in tRNA and rRNAs or secondary LHON mutations in these seven Chinese families. These suggest that these mtDNA haplogroup-specific variants may not play an important role in the phenotypic expression of the A1555G mutation in those Chinese families with very low penetrance of hearing loss. However, aminoglycosides appear to be a major modifier factor for the phenotypic manifestation of the A1555G mutation in these Chinese families.

Aminoglycoside-induced and non-syndromic hearing loss is associated with the G7444A mutation in the mitochondrial COI/tRNASer(UCN) genes in two Chinese families.

We report here the clinical, genetic, and molecular characterization of two Chinese families with aminoglycoside induced and non-syndromic hearing impairment. Clinical and genetic evaluations revealed the variable severity and age-of-onset in hearing impairment in these families. Strikingly, there were extremely low penetrances of hearing impairment in these Chinese families. Sequence analysis of the complete mitochondrial genomes in these pedigrees showed the distinct sets of mtDNA polymorphism, in addition to the identical G7444A mutation associated with hearing loss. Indeed, the G7444A mutation in the CO1 gene and the precursor of tRNASer(UCN) gene is present in homoplasmy only in the maternal lineage of those pedigrees but not other members of these families and 164 Chinese controls. Their mitochondrial genomes belong to the Eastern Asian haplogroups C5a and D4a, respectively. In fact, the occurrence of the G7444A mutation in these several genetically unrelated subjects affected by hearing impairment strongly indicates that this mutation is involved in the pathogenesis of hearing impairment. However, there was the absence of other functionally significant mtDNA mutations in two Chinese pedigrees carrying the G7444A mutation. Therefore, nuclear modifier gene(s) or aminoglycoside(s) may play a role in the phenotypic expression of the deafness-associated G7444A mutation in these Chinese pedigrees.