MPZL2-a common autosomal recessive deafness gene related to moderate sensorineural hearing loss in the Chinese population

BACKGROUND

Mutations in MPZL2, the characteristic genetic etiology of autosomal recessive deafness loci 111 (DFNB111), cause non-syndromic and moderate sensorineural hearing loss.

METHODS

In this study, we analyzed the phenotype and genotype of eight pedigrees consisting of 10 hearing loss patients with bi-allelic pathogenic or likely pathogenic variants in MPZL2. These patients were identified from a 3272 Chinese patient cohort who underwent genetic testing.

RESULTS

Apart from symmetrical and moderate sensorineural hearing loss, the MPZL2-related phenotype was characterized by progressive hearing loss with variation in the onset age (congenital defect to onset at the young adult stage). We determined that in the Chinese population, the genetic load of MPZL2 defects was 0.24% (8/3272) in patients diagnosed with hearing loss and 7.02% (8/114) in patients diagnosed with hereditary moderate sensorineural hearing loss caused by STRC, OTOA, OTOG, OTOGL, TECTA, MPZL2 and others. Three known MPZL2 variants (c.220C > T (p.Gln74*), c.68delC (p.Pro23Leufs*2), c.463delG (p.Ala155Leufs*10)) and a novel start loss variant (c.3G > T (p.Met1?)) were identified. MPZL2 c.220C > T was identified as the hotspot variant in the Chinese population and even in East Asia compared with c.72delA (p.Ile24Metfs*22) in European and West Asia through allele frequency.

CONCLUSIONS

We concluded that apart from moderate HL, progressive HL is another character of MPZL2-related HL. No specified variant was verified for the progression of HL, the penetrance and expressivity cannot be determined yet. A novel MPZL2 variant at the start codon was identified, enriching the variant spectrum of MPZL2. The hotspot variants of MPZL2 vary in different ethnicities. This study provides valuable data for the diagnosis, prognosis evaluation and genetic counseling of patients with moderate sensorineural hearing loss related to MPZL2.

[Establishment and validation of nomogram prediction model for complicated acute appendicitis]

Objective: To establish and internally validate a nomogram model for predicting complicated acute appendicitis (CA). Methods: The clinical data from 663 acute appendicitis patients from the First Affiliated Hospital of Anhui University of Traditional Chinese Medicine from October 2015 to October 2022 were retrospectively analyzed. There were 411 males and 252 females, aged (M (IQR)) 41 (22) years (range: 18 to 84 years). There were 516 cases of CA and 147 cases of uncomplicated acute appendicitis. The minimum absolute contraction and selection operator regression model was used to screen the potential relative factors of CA, and the screened factors were included in the Logistic regression model for multivariate analysis. Software R was used to establish a preoperative CA nomogram prediction model, the receiver operating characteristic curve of the model was drawn, and the value of area under the curve (AUC) was compared to evaluate its identification ability, and the Bootstrap method was used for internal verification. Results: The elderly (age≥60 years) (OR=2.428, 95%CI: 1.295 to 4.549), abdominal pain time (every rise of 1 hour) (OR=1.089, 95%CI: 1.072 to 1.107), high fever (body temperature≥39 ℃) (OR=1.122, 95%CI: 1.078 to 1.168), total bilirubin (every rise of 1 μmol/L) (OR=2.629, 95%CI: 1.227 to 5.635) were independent relative factors of CA (all P<0.05). The AUC of this model was 0.935 (95%CI: 0.915 to 0.956). After internal verification using the Bootstrap method, the model still had a high discrimination ability (AUC=0.933), and the predicted CA curve was still in good agreement with the actual clinical CA curve. Conclusion: The clinical prediction model based on the elderly (age≥60 years), prolonged abdominal pain time, high fever (body temperature≥39 ℃), and increased total bilirubin can help clinicians effectively identify CA.

[Phenotype-genotype analysis of the autosomal recessive hereditary hearing loss caused by OTOA variations]

Objective: To analyze the phenotypic-genotypic characteristics of hereditary deafness caused by OTOA gene variations. Methods: Family histories, clinical phenotypes and gene variations of six pedigrees were analyzed, which were diagnosed with hearing loss caused by OTOA gene variations at the PLA General Hospital from September 2015 to January 2022. The sequence variations were verified by Sanger sequencing and the copy number variations were validated by multiplex ligation-dependent probe amplification (MLPA) in the family members. Results: The hearing loss phenotype caused by OTOA variations ranged from mild to moderate in the low frequencies, and from moderate to severe in the high frequencies in the probands, which came from six sporadic pedigrees, among which a proband was diagnosed as congenital deafness and five were diagnosed as postlingual deafness. One proband carried homozygous variations and five probands carried compound heterozygous variations in OTOA gene. Nine pathogenic variations (six copy number variations, two deletion variations and one missense variation) and two variations with uncertain significance in OTOA were identified in total, including six copy number variations and five single nucleotide variants, and three of the five single nucleotide variants were firstly reported [c.1265G>T(p.Gly422Val),c.1534delG(p.Ala513Leufs*11) and c.3292C>T(p.Gln1098fs*)]. Conclusions: OTOA gene variations can lead to autosomal recessive nonsyndromic hearing loss. In this study, the hearing loss caused by OTOA defects mostly presents as bilateral, symmetrical, and postlingual, and that of a few presents as congenital. The pathogenic variations of OTOA gene are mainly copy number variations followed by deletion variations and missense variations.

A newborn male with Myhre syndrome, hearing loss, and complete syndactyly of fingers 3-4

BACKGROUND

Myhre syndrome is a rare multisystem genetic disorder that is caused by de novo heterozygous gain-of-function variants in SMAD4. Patients with Myhre syndrome exhibit several phenotypes at different ages such as small size, autism, developmental delay, left-sided heart defects, and hearing loss and often have a characteristic facial appearance. The early clinical diagnosis of Myhre syndrome remains a major challenge, particularly in the first year of life.

METHODS

A Chinese male infant with syndactyly of fingers, hypertelorism, short palpebral fissures, and short philtrum was enrolled into the ENT department of the Chinese PLA General Hospital. Whole exome sequencing analysis was used to detect the disease-causing variant. A literature review of Myhre syndrome was also performed.

RESULTS

A recurrent de novo missense variant c.1498A > G p.I500V(p. Ile500Val) in SMAD4 was detected confirming the clinical diagnosis of Myhre syndrome at the age of 38 days. The infant appears to be the youngest reported case of Myhre syndrome. At 23-month follow-up, the affected infant has dysmorphic facial features, growth retardation, and previously undescribed complete syndactyly. Review the literatures noted several common features in Myhre syndrome patients including hearing loss (72.7%), characteristic facial features (26.0%-54.5%), finger and toe abnormalities (3.9%-48.1%), short stature (45.5%), and respiratory (30.0%) and cardiovascular problems (65.0%).

CONCLUSIONS

Clinicians should have a low threshold to perform genetic testing on patients with features suggesting Myhre syndrome even in the first year of life. Although some individuals with Myhre syndrome have normal hearing, early onset or progressive hearing loss usually occur in one or both ears in most patients, with remarkable phenotypic heterogeneity. Syndactyly may be minor such as typical 2-3 toe involvement, or more complicated as was observed in our patient.

Addition of an affected family member to a previously ascertained autosomal recessive nonsyndromic hearing loss pedigree and systematic phenotype-genotype analysis of splice-site variants in MYO15A

Pathogenic variants in MYO15A are known to cause autosomal recessive nonsyndromic hearing loss (ARNSHL), DFNB3. We have previously reported on one ARNSHL family including two affected siblings and identified MYO15A c.5964+3G > A and c.8375 T > C (p.Val2792Ala) as the possible deafness-causing variants. Eight year follow up identified one new affected individual in this family, who also showed congenital, severe to profound sensorineural hearing loss. By whole exome sequencing, we identified a new splice-site variant c.5531+1G > C (maternal allele), in a compound heterozygote with previously identified missense variant c.8375 T > C (p.Val2792Ala) (paternal allele) in MYO15A as the disease-causing variants. The new affected individual underwent unilateral cochlear implantation at the age of 1 year, and 5 year follow-up showed satisfactory speech and language outcomes. Our results further indicate that MYO15A-associated hearing loss is good candidates for cochlear implantation, which is in accordance with previous report. In light of our findings and review of the literatures, 58 splice-site variants in MYO15A are correlated with a severe deafness phenotype, composed of 46 canonical splice-site variants and 12 non-canonical splice-site variants.

Genetic Analysis of the LOXHD1 Gene in Chinese Patients With Non-Syndromic Hearing Loss

Non-syndromic hearing loss (NSHL) is a common neurosensory disease with an extreme genetic heterogeneity which has been linked to variants in over 120 genes. The LOXHD1 gene (DFNB77), encoding lipoxygenase homology domain 1, is a rare hearing loss gene found in several populations. To evaluate the importance of LOXHD1 variants in Chinese patients with NSHL, we performed genetic analysis on LOXHD1 in 2,901 sporadic Chinese patients to identify the aspect and frequency of LOXHD1 causative variants. Next-generation sequencing using a custom gene panel of HL was conducted on 2,641 unrelated patients and whole-exome sequencing on the remaining 260 patients. A total of 33 likely causative variants were identified in 21 patients, including 20 novel variants and 13 previously reported pathogenic variants. Each of the 20 novel variants was evaluated according to ACMG criteria. These findings showed that causative variants in LOXHD1 were found in about 0.72% (21/2,901) of Chinese NSHL patients. This study is by far the largest number of novel variants identified in this gene expanding the range of pathogenic variants in LOXHD1, and suggests that variants in this gene occur relatively commonly in Chinese NSHL patients. This extensive investigation of LOXHD1 in Chinese NSHL patients proposed six recurrent LOXHD1 variants. These findings may assist in both molecular diagnosis and genetic counseling.

Transcriptome analysis of the early stage ifnlr1-mutant zebrafish indicates the immune response to auditory dysfunction

BACKGROUND

IFNLR1 has been recently identified to be related to autosomal dominant nonsyndromic sensorineural hearing loss (ADNSHL). It is reported to be expressed in the inner ear of mice and the lateral line of zebrafish. However, it remains unclear how defects in this gene lead to hearing loss.

OBJECTIVES

To elucidate the global gene expression changes in zebrafish when the expression of ifnlr1 is downregulated.

METHODS

Transcriptome analysis was performed on ifnlr1 morpholino knockdown zebrafish and the control zebrafish using RNA-seq technology.

RESULTS

The results show that 262 differentially expressed genes (DEGs) were up-regulated while 146 DEGs were down-regulated in the E4I4-Mo zebrafish larvae compared to the control-Mo. Six pathways were significantly enriched, including steroid biosynthesis pathway, adipocytokine signaling pathway, cytokine-cytokine receptor interaction pathway, p53 signaling pathway, AGE-RAGE signaling pathway in diabetic complications, and terpenoid backbone biosynthesis pathway. Among them, three pathways (steroid biosynthesis pathway, cytokine-cytokine receptor interaction pathway and p53 signaling pathway) are immune-associated.

CONCLUSIONS

The transcriptome analysis results contribute to the groundwork for future research on the pathogenesis of IFNLR1-associated hearing loss.

[Analysis of COL1A1 gene variation and clinical prevention and treatment in patients with Van der Hoeve syndrome]

Objective: To investigate the clinical phenotype, treatment and prevention of Van der Hoeve syndrome, and analyze the variation characteristics of its related gene COL1A1. Methods: Hearing and sequencing data of syndromic deafness patients who had undergone genetic testing for deafness at the Chinese People's Liberation Army General Hospital since January 2008 to October 2020 were retrospectively reviewed. The variation of the COL1A1 gene and return visits to traceable patients and families were summarized, the disease progress and clinical treatment effects were analyzed, and the prevention strategies were discussed. Results: A total of 7 patients with COL1A1 gene mutation underwent clinical intervention. The mutation sites were c.1342A>T (p.Lys448*), c.124C>T (p.Gln42*), c.249insG(p.Ala84*), c.668insC(p.Gly224*), c.2829+1G>C, c.1081C>T (p.Arg361*), c.1792C>T (p.Arg598*), of which c.1081C>T and c.1792C>T had been previously reported, and the remaining 5 were novo mutations that have not been reported. All the 7 probands underwent stapes implantation and received genetic counseling and prevention guidance. Conclusions: Van der Hoeve syndrome belongs to osteogenesis imperfecta type Ⅰ. The disease has high penetrance. Timely surgical intervention for hearing loss can improve the life quality in patients. Accurate genetic counseling and preimplantation genetic diagnosis can achieve the primary prevention for the disease.

A novel variant in FOXC1 associated with atypical Axenfeld-Rieger syndrome

Mutations in the Forkhead Box C1 (FOXC1) are known to cause autosomal dominant hereditary Axenfeld-Rieger syndrome, which is a genetic disorder characterized by ocular and systemic features including glaucoma, variable dental defects, craniofacial dysmorphism and hearing loss. Due to late-onset of ocular disorders and lack of typical presentation, clinical diagnosis presents a huge challenge. In this study, we described a pathogenic in-frame variant in FOXC1 in one 5-year-old boy who is presented with hypertelorism, pupil deformation in both eyes, conductive hearing loss, and dental defects. By whole exome sequencing, we identified a 3 bp deletion in FOXC1, c.516_518delGCG (p.Arg173del) as the disease-causing variant, which was de novo and not detected in the parents, and could be classified as a "pathogenic variant" according to the American College of Medical Genetics and Genomics guidelines. After confirmation of this FOXC1 variant, clinical data on Axenfeld-Rieger syndrome-associated clinical features were collected and analyzed. Furthermore, Although the affected individual present hearing loss, however, the hearing loss is conductive and is reversible during the follow-up, which might not linke to the FOXC1 variant and is coincidental. Routine examination of FOXC1 is necessary for the genetic diagnosis of hypertelorism-associated syndrome. These findings may assist clinicians in reaching correct clinical and molecular diagnoses, and providing appropriate genetic counseling.

Generation of a gene corrected human isogenic iPSC line (CPGHi002-A-1) from a DDOD patient with heterozygous c.1516 C>T mutation in the ATP6V1B2 gene

Dominant deafness-onychodystrophy (DDOD) syndrome is a rare autosomal dominant disorder caused by mutations in ATP6V1B2 gene. We previously generated an induced pluripotent stem cell (iPSC) line (CPGHi002-A) from a DDOD patient with a heterozygous c.1516 C>T mutation in the ATP6V1B2 gene. Here we genetically corrected the c.1516 C>T mutation in the ATP6V1B2 gene using CRISPR/Cas9 technology to generate an isogenic control, CPGHi002-A-1. The characterization of CPGHi002-A-1 demonstrates normal karyotype, pluripotent state, and potential to differentiate in vitro towards endoderm, mesoderm, and ectoderm.

[Phenotype and genotype analysis of recessive hereditary moderate sensorineural hearing loss caused by new mutations in OTOGL gene]

Objective: To perform the phenotype and genetic analysis on two families with moderate sensorineural hearing impairment and determine the cause of deafness. Methods: The phenotype and genetic analysis was performed on the two hearing impairment pedigrees coming to Chinese PLA General Hospital from January 2014 to August 2020. DNA samples of the proband from family 1 and the parents from family 2 were collected and tested through next generation sequencing on all deafness genes, and Sanger sequencing was performed to verify the mutation sites. The reported pathogenic variants of the otogelin-like (OTOGL) gene, the autosomal recessive inherited deafness genes that cause moderate sensorineural hearing loss and the clinical manifestations of the deafness genes that have the similar expression location as the OTOGL gene were summarized and analyzed. Results: The pathogenic variants in the families were compound heterozygous variants in the OTOGL gene c.2773C>T/c.2826C>G (p.Arg925*/p.Tyr942*) and c.4455G>A/c.875C>G (Trp1485*/p.Ser292*), respectively. c.2773C>T was an already reported pathogenic variant causing hearing impairment in the literature, while c.2826C>G, c.4455G>A and c.875C>G were novel reported variant sites. The above four variants were classified as pathogenic variants according to the variant interpretation standards and guideline of the Amercian College of Medical Genetics and Genomics. Conclusions: Pathogenic variants in OTOGL gene is an important genetic factor leading to moderate sensorineural hearing loss. The newly discovered variant sites c.2826C>G, c.4455G>A and c.875C>G enrich the variant spectrum of OTOGL gene. The results of the current study provide a basis for genetic counseling of the related families and a new target for the treatment of hereditary hearing loss in the future.

[Surgical strategy of minimally invasive cochlear implantation]

Cochlear implantation is currently the most effective treatment for patients with severe-to-profound sensorineural hearing loss. How to achieve minimally invasive treatment, preserve the residual hearing, and further improve curative effect and reduce surgical complications is the goal of cochlear implantation practice. This article introduces the minimally invasive cochlear implantation technique in terms of the idea of minimally invasive operation, the advantages of electric acoustic stimulation, the key points of electrode implantation technique, the design of surgical incision, and the precise processing of perioperative period. This technique not only has the merits of less operative damage and better hearing and speech rehabilitation after surgery, but also reserves favorable structures and function for the future application of gene therapy and hair cell regeneration technique. Therefore, it is strongly recommended for further promotion in clinical practice.

Congenital sensorineural hearing loss as the initial presentation of PTPN11-associated Noonan syndrome with multiple lentigines or Noonan syndrome: clinical features and underlying mechanisms

BACKGROUND

Germline variants in PTPN11 are the primary cause of Noonan syndrome with multiple lentigines (NSML) and Noonan syndrome (NS), which share common skin and facial symptoms, cardiac anomalies and retardation of growth. Hearing loss is considered an infrequent feature in patients with NSML/NS. However, in our cohort, we identified a group of patients with PTPN11 pathogenic variants that were primarily manifested in congenital sensorineural hearing loss (SNHL). This study evaluated the incidence of PTPN11-related NSML or NS in patients with congenital SNHL and explored the expression of PTPN11 and the underlying mechanisms in the auditory system.

METHODS

A total of 1502 patients with congenital SNHL were enrolled. Detailed phenotype-genotype correlations were analysed in patients with PTPN11 variants. Immunolabelling of Ptpn11 was performed in P35 mice. Zebrafish with Ptpn11 knockdown/mutant overexpression were constructed to further explore mechanism underlying the phenotypes.

RESULTS

Ten NSML/NS probands were diagnosed via the identification of pathogenic variants of PTPN11, which accounted for ~0.67% of the congenital SNHL cases. In mice cochlea, Shp2, which is encoded by Ptpn11, is distributed in the spiral ganglion neurons, hair cells and supporting cells of the inner ear. In zebrafish, knockdown of ptpn11a and overexpression of mutant PTPN11 were associated with a significant decrease in hair cells and supporting cells. We concluded that congenital SNHL could be a major symptom in PTPN11-associated NSML or NS. Other features may be mild, especially in children.

CONCLUSION

Screening for PTPN11 in patients with congenital hearing loss and variant-based diagnoses are recommended.

Concurrent Hearing and Genetic Screening of 180,469 Neonates with Follow-up in Beijing, China

Concurrent hearing and genetic screening of newborns is expected to play important roles not only in early detection and diagnosis of congenital deafness, which triggers intervention, but also in predicting late-onset and progressive hearing loss and identifying individuals who are at risk of drug-induced HL. Concurrent hearing and genetic screening in the whole newborn population in Beijing was launched in January 2012. This study included 180,469 infants born in Beijing between April 2013 and March 2014, with last follow-up on February 24, 2018. Hearing screening was performed using transiently evoked otoacoustic emission (TEOAE) and automated auditory brainstem response (AABR). For genetic testing, dried blood spots were collected and nine variants in four genes, GJB2, SLC26A4, mtDNA 12S rRNA, and GJB3, were screened using a DNA microarray platform. Of the 180,469 infants, 1,915 (1.061%) were referred bilaterally or unilaterally for hearing screening; 8,136 (4.508%) were positive for genetic screening (heterozygote, homozygote, or compound heterozygote and mtDNA homoplasmy or heteroplasmy), among whom 7,896 (4.375%) passed hearing screening. Forty (0.022%) infants carried two variants in GJB2 or SLC26A4 (homozygote or compound heterozygote) and 10 of those infants passed newborn hearing screening. In total, 409 (0.227%) infants carried the mtDNA 12S rRNA variant (m.1555A>G or m.1494C>T), and 405 of them passed newborn hearing screening. In this cohort study, 25% of infants with pathogenic combinations of GJB2 or SLC26A4 variants and 99% of infants with an m.1555A>G or m.1494C>T variant passed routine newborn hearing screening, indicating that concurrent screening provides a more comprehensive approach for management of congenital deafness and prevention of ototoxicity.

[PTPN11 and the deafness]

Summary PTPN11 gene encodes tyrosine phosphatase SHP-2 which locates on chromosome 12（12q24.1）, expresses in most embryonic and adult tissues, and plays pivotal roles in cell proliferation, differentiation, survival and cell death. SHP-2 apparently participates in signaling events downstream of RAS-MAPK and JAK/STAT. Diseases related to PTPN11 gene mutations include the Noonan syndrome（NS） and the NS with Multiple Lentigines（NSML）. Both NS and NSML contain the phenotypes of deafness, craniofacial anomalies, short stature, congenital heart defects, skin disorders, ophthalmologic abnormalities and cancer predisposition.

[Case report and diagnosis of Noonan syndrome with multiple lentigines with deafness as its main clinical feature]

Summary Noonan syndrome with multiple lentigines（NSML） is a disorder with syndromic hearing loss. Abnormalities of other systems in NSML have received increasing attention, but hearing loss is rarely concerned. And due to the incomplete phenotype, some patients with NSML maybe missed or maybe confused with other syndromic deafness such as Waardenburg syndrome. Our study will familiarize more otolaryngologists with Leopard syndrome. A 5-year-old boy with bilateral sensorineural hearing loss and numerous symmetrically distributed dark brown macules that had good effect of cochlear implantation was collected in this study. And his father had bilateral sensorineural hearing loss and numerous symmetrically distributed dark brown macules. Waardenburg syndrome was initially diagnosed by clinical phenotype and its molecular etiology was confirmed by gene diagnosis. Waardenburg syndrome-related deafness genes and 131 known deafness genes were not identified by second-generation sequencing. Whole-exon sequencing was performed for 4 individuals in the family and the results were confirmed by Sanger sequencing. This study confirmed the diagnosis by identifying a disease-causing mutation in the PTPN11 gene, which was a heterozygous missense mutation at p. Tyr279Cys（c. 836A>G）. The mutation co-segregated with hearing loss in the family. Our results demonstrated that hearing loss in this family was caused by heterozygous mutations in PTPN11. These cases will familiarize more otolaryngologists with NSML, and they emphasize the importance of considering NSML as a possible cause of hearing problems.

[One novel pathologic variation in KMT2D cause Kabuki syndrome with hearing loss as the main phenotype and related research on types of deafness]

Objective:To make the molecular diagnosis of a patient complaining hearing loss and with specific facial features, developmental delay, vertebral dysplasia, hypotonia and other suspected phenotypes of Kabuki make-up syndrome（KS）; to investigate the characteristics and main phenotypes of KS. Method:①Whole-exome sequencing and bioinformatics analysis were performed for proband and her parents. ②Literatures describing the clinical features of KS patients with clear molecular diagnosis from the period of Aug 2010 to Mar 2019 were collected from databases of PubMed and CNKI. Result:①The proband carries the c. 15777insT variant（p. Pro5260fs*10） in KMT2D gene. The variant causes the termination codon to appear prematurely. KMT2D c. 15777insT was classified as PVS1+PS1+PM2 according to the ACMG variation interpretation standard, which is a disease-causing mutation. The c. 15777insT was first reported as a pathogenic mutation of KS. ②77 peer-reviewed publications on KS were analysed including 462 patients with KS. The main findings were intellectual disability（305 cases）, congenital heart defects（227 cases）, hypotonia（184 cases）, short fingers（147 cases）, short stature（144 cases）, cleft palate（139 cases）, hearing loss（101 cases） and developmental delay（99 cases）. Of the 101 patients with hearing loss, 11 were confirmed to have conductive hearing loss（1 with recurrent otitis media）, 3 with mixed hearing loss, 12 with sensorineural deafness（1 with recurrence otitis media） and 75 patients with unidentified types of deafness（28 with recurrent otitis media）. Conclusion:KS involves defects of a wide range of organs, with each organ showing different severity of symptoms, which is easily misdiagnosed from the phenotypes. We suggest the diagnosis on hearing loss in KS patients should be strengthened. KMT2D and KDM6A are two pathogenic genes that have been identified for KS. With the increase of age, its typical clinical phenotypes become more and more obvious. When there is only atypical suspected KS symptoms in the early neonatal period, relevant genetic test should be performed as soon as possible to achieve early diagnosis and intervention.

[Histocompatibility of an original Chinese-made mid-urethral sling in a rabbit model]

Objective: To evaluate the histocompatibility of an original Chinese-made mid-urethral sling (Repelvica mid-urethral sling). Methods: In total 10 female New Zealand white rabbits were implanted with Repelvica mid-urethral sling or tension-free vaginal tape-obturator tape (TVT-O; Gynecare). Both brands of sling were implanted under deep fascia of the abdominal wall and in the space between vagina and bladder. All animal groups were sacrificed at set time intervals (4 weeks and 12 weeks), and the abdominal and vaginal slings were harvested for histological evaluation. Results: All slings appeared to be well incorporated into the abdominal wall and anterior vaginal wall. All specimens showed a thin, loose, fibrous interface between the synthetic graft and abdominal wall or vaginal wall, along with mild inflammatory reaction from 4 weeks to 12 weeks. Abdominal grafts of Repelvica mid-urethral sling and TVT-O induced comparable tissue reaction (histological score 10.5 versus 10.5 at 4 weeks, 10.0 versus 9.5 at 12 weeks; both P>0.05). Vaginal grafts of Repelvica mid-urethral sling had lower histological score than TVT-O (histological score 6.0 versus 12.0 at 4 weeks, 8.5 versus 12.5 at 12 weeks), however the differences were not statistically significant (both P>0.05). Conclusions: Chinese-made Repelvica mid-urethral sling exhibits good histocompatibility. Vaginal graft of Repelvica mid-urethral sling evoks minor tissue reaction, which could be attributed to its lightweighted property and favored its clinical application.

Cochlear implantation in patients with canal wall down mastoidectomy cavities

BACKGROUND

Safe cochlear implantation (CI) is challenging in patients with a canal wall down (CWD) mastoidectomy cavity.

OBJECTIVES

We reviewed the outcomes of CI and proposed surgical management principles according to the presentation status of CWD mastoidectomy cavity.

MATERIAL AND METHODS

The cases of eight patients (nine ears) with CWD mastoidectomy cavity who underwent CI were retrospectively reviewed. The basis of the surgical decision, postoperative complications, and postimplant auditory performance were analysed.

RESULTS

In seven patients (eight ears), implantation was performed in a single stage; in six ears, the external auditory canal (EAC) was oversewn. In two patients with ossification, the electrode array was inserted into the scala tympani by drilling of the basal turn or in the second turn of the cochlea through a drill-out procedure. Seven patients had a follow-up of 12-50 months and one patient was lost to follow-up. None of the followed-up seven patients suffered complications.

CONCLUSIONS

CI is safe and effective in patients with profound hearing loss after radical mastoidectomy. In patients with CWD mastoidectomy cavity, CI does not cause a higher rate of postoperative complications relative to standard CI procedures. The outcome is excellent and comparable to that in the general CI population.

Mutation of IFNLR1, an interferon lambda receptor 1, is associated with autosomal-dominant non-syndromic hearing loss

Background Hereditary sensorineural hearing loss is a genetically heterogeneous disorder. Objectives This study was designed to explore the genetic etiology of deafness in a large Chinese family with autosomal dominant, nonsyndromic, progressive sensorineural hearing loss (ADNSHL). Methods Whole exome sequencing and linkage analysis were performed to identify pathogenic mutation. Inner ear expression of Ifnlr1 was investigated by immunostaining in mice. ifnlr1 Morpholino knockdown Zebrafish were constructed to explore the deafness mechanism. Results We identified a cosegregating heterozygous missense mutation, c.296G>A (p.Arg99His) in the gene encoding interferon lambda receptor 1 (IFNLR1) - a protein that functions in the Jak/ STAT pathway- are associated with ADNSHL Morpholino knockdown of ifnlr1 leads to a significant decrease in hair cells and non-inflation of the swim bladder in late-stage zebrafish, which can be reversed by injection with normal Zebrafish ifnlr1 mRNA. Knockdown of ifnlr1 in zebrafish causes significant upregulation of cytokine receptor family member b4 (interleukin-10r2), jak1, tyrosine kinase 2, stat3, and stat5b in the Jak1/STAT3 pathway at the mRNA level. ConclusionIFNLR1 function is required in the auditory system and that IFNLR1 mutations are associated with ADNSHL. To the best of our knowledge, this is the first study implicating an interferon lambda receptor in auditory function.

A novel mutation in POU3F4 in a Chinese family with X-linked non-syndromic hearing loss

Objective

Based on the clinical manifestations of a hearing loss patient, the POU3F4 gene was tested for diagnosis of etiology.

Methods

A comprehensive physical examination was performed on the proband to exclude abnormalities of other organs, and detailed audiological testing and temporal bone CT scan were also performed. Genomic DNA was extracted using the proband's peripheral blood leukocytes. Polymerase chain reactions (PCR) were performed in the coding sequence of the POU3F4 gene. Direct DNA sequencing was subsequently applied to screen the entire coding region of the POU3F4 gene.

Results

The proband had severe sensorineural hearing loss. Temporal CT showed bilateral cochlear incomplete partition, vestibule dysplasia, internal auditory canal fundus expansion, and cochlear interlink with the internal auditory canal fundus. A novel mutation (c.530C > A (p.S177X)) in the POU3F4 gene was found in this patient, creating an new stop codon and was predicted to result in a truncated protein lacking normal POU3F4 transcription factor function.

Conclusion

Through analysis of the POU3F4 gene and clinical manifestations in the patient, we conclude that a novel mutation may have resulted in a premature stop codon, contributing to the mutation of POU3F4 gene.

Correlation analysis of phenotype and genotype of GJB2 in patients with non-syndromic hearing loss in China

BACKGROUND

Disease-associated mutations in GJB2 gene are one of the major reasons that can cause non-syndromic sensorineural hearing loss (NSHL). GJB2 gene deafness has various clinical phenotypes. This study aims to analyze characteristics and relationships of clinical phenotypes through analyzing 1481 NSHL cases and 190 GJB2 deafness patients (with dual gene mutations).

PATIENTS AND METHODS

All the patients diagnosed as deaf disease molecular diagnostics were obtained from the people's liberation army general hospital from March 2007 to March 2011. The accession number of GJB2 was NM_004004 in GenBank, and sequence alignment and annotation were performed using GeneTool software.

RESULTS

In NSHL patients, mutated allele frequency in GJB2 was 20.57%, and the preponderant type was c.235delC (11.84%) followed by c.109G>A (3.75%). Mutation rate of double allelic gene was 16.18%, including 8.43% of homozygous mutation rate and 7.75% of recombination heterozygosis mutation. Moreover, auditory threshold of GJB2 biallelic marker was associated with ages of onset, while no significant correlation was detected with disease time and whether the inner ear malformation. Similar clinical phenotype could be detected between patients with c.109G>A dual gene mutation and dual gene mutation. However, in the aspect of hearing impairment, the phenomenon of pathopoiesia caused by mutation of c.109G>A was poorer than the other mutations, and even near those patients without pathogenic mutations.

CONCLUSION

Our study further shows the definite relationship of clinical phenotype and genotype in GJB2 gene correlated deafness, and these results can provide basis for revealing pathogenesis, gene diagnosis and consult of deafness. The level of evidence in the study is level 4 (case series).

Targeted gene capture and massively parallel sequencing identify TMC1 as the causative gene in a six-generation Chinese family with autosomal dominant hearing loss

Hereditary nonsyndromic hearing loss is extremely heterogeneous. Mutations in the transmembrane channel-like gene1 (TMC1) are known to cause autosomal dominant and recessive forms of nonsyndromic hearing loss linked to the loci of DFNA36 and DFNB7/11, respectively. We characterized a six-generation Chinese family (5315) with progressive, postlingual autosomal dominant nonsyndromic hearing loss (ADNSHL). By combining targeted capture of 82 known deafness genes, next-generation sequencing and bioinformatic analysis, we identified TMC1 c.1714G>A (p. D572N) as the disease-causing mutation. This mutation co-segregated with hearing loss in other family members and was not detected in 308 normal controls. In order to determine the prevalence of TMC1 c.1714G>A in Chinese ADNSHL families, we used DNA samples from 67 ADNSHL families with sloping audiogram and identified two families carry this mutation. To determine whether it arose from a common ancestor, we analyzed nine STR markers. Our results indicated that TMC1 c.1714G>A (p.D572N) account for about 4.4% (3/68) of ADNSHL in the Chinese population.

Identification of Two Novel Compound Heterozygous PTPRQ Mutations Associated with Autosomal Recessive Hearing Loss in a Chinese Family

Mutations in PTPRQ are associated with deafness in humans due to defects of stereocilia in hair cells. Using whole exome sequencing, we identified responsible gene of family 1572 with autosomal recessively non-syndromic hearing loss (ARNSHL). We also used DNA from 74 familial patients with ARNSHL and 656 ethnically matched control chromosomes to perform extended variant analysis. We identified two novel compound heterozygous missense mutations, c. 3125 A>G p.D1042G (maternal allele) and c.5981 A>G p.E1994G (paternal allele), in the PTPRQ gene, as the cause of recessively inherited sensorineural hearing loss in family 1572. Both variants co-segregated with hearing loss phenotype in family 1572, but were absent in 74 familial patients. Heterozygosity for c. 3125 A>G was identified in two samples from unaffected Chinese individuals (656 chromosomes). Therefore, the hearing loss in this family was caused by two novel compound heterozygous mutations in PTPRQ.

Novel compound heterozygous mutations in MYO7A Associated with Usher syndrome 1 in a Chinese family

Usher syndrome is an autosomal recessive disease characterized by sensorineural hearing loss, age-dependent retinitis pigmentosa (RP), and occasionally vestibular dysfunction. The most severe form is Usher syndrome type 1 (USH1). Mutations in the MYO7A gene are responsible for USH1 and account for 29–55% of USH1 cases. Here, we characterized a Chinese family (no. 7162) with USH1. Combining the targeted capture of 131 known deafness genes, next-generation sequencing, and bioinformatic analysis, we identified two deleterious compound heterozygous mutations in the MYO7A gene: a reported missense mutation c.73G>A (p.G25R) and a novel nonsense mutation c.462C>A (p.C154X). The two compound variants are absent in 219 ethnicity-matched controls, co-segregates with the USH clinical phenotypes, including hearing loss, vestibular dysfunction, and age-dependent penetrance of progressive RP, in family 7162. Therefore, we concluded that the USH1 in this family was caused by compound heterozygous mutations in MYO7A.

Sequence characterization, polymorphism, and tissue expression profile of an effector immediate-early gene: activity-regulated cytoskeletal associated protein gene (Arc/Arg3.1) in swamp and river buffalo

The activity-regulated cytoskeletal associated protein (Arc/Arg3.1) has been implicated in experience-dependent synaptic plasticity and memory formation. However, information regarding its coding gene in buffalo remains scarce. In this study, the full-length of Arc/Arg3.1 was isolated and characterized (accession No. JX491649) and genetic variations of six river buffalo and eight swamp buffalo were investigated. A tissue expression profile was obtained using semi-quantitative reverse transcription-polymerase chain reaction. The coding region sequence of Arc/Arg3.1 contained 1191 nucleotides encoding a putative protein of 396 amino acids with a theoretical isoelectric point (pI) and molecular weight (Mw) of 5.4 and 45.2 kDa, respectively. Four polymorphisms (c.63T>C, c.228T>C, c.558G>A, and c.625G>C) were found in buffalo; however, only substitution c.625G>C was non-synonymous, leading to an amino acid change from Val to Leu at the 209th position of the Arc/Arg3.1 protein sequence. Bioinformatics analysis revealed that this substitution had no significant effect on Arc/Arg3.1 function (subPSEC = -1.4039, Pdeleterious = 0.1685), which indicated that Arc/Arg3.1 was highly conserved and functionally important in buffalo. Phylogenetic analysis revealed that the gene is closely related to that of Bos taurus and Bos grunniens. The gene was moderately expressed in the hypophysis and the placenta; it was weakly expressed in the kidney, milk, mammary gland, cerebrum, lung, heart, rumen, fat, and uterus; and it was almost silent in the muscle, liver, and skin. These findings will provide further insights into the structure and function of the immediate-early gene in buffalo.

A novel mutation in the TECTA gene in a Chinese family with autosomal dominant nonsyndromic hearing loss

TECTA-related deafness can be inherited as autosomal-dominant nonsyndromic deafness (designated DFNA) or as the autosomal-recessive version. The α-tectorin protein, which is encoded by the TECTA gene, is one of the major components of the tectorial membrane in the inner ear. Using targeted DNA capture and massively parallel sequencing (MPS), we screened 42 genes known to be responsible for human deafness in a Chinese family (Family 3187) in which common deafness mutations had been ruled out as the cause, and identified a novel mutation, c.257-262CCTTTC>GCT (p. Ser86Cys; p. Pro88del) in exon 3 of the TECTA gene in the proband and his extended family. All affected individuals in this family had moderate down-sloping hearing loss across all frequencies. To our knowledge, this is the second TECTA mutation identified in Chinese population. This study demonstrates that targeted genomic capture, MPS, and barcode technology might broaden the availability of genetic testing for individuals with undiagnosed DFNA.

Novel compound heterozygous mutations in the MYO15A gene in autosomal recessive hearing loss identified by whole-exome sequencing

Background

Inherited genetic defects play an important role in congenital hearing loss, contributing to about 60% of deafness occurring in infants. Hereditary nonsyndromic hearing loss is highly heterogeneous, and most patients with a presumed genetic etiology lack a specific molecular diagnosis.

Methods

By whole exome sequencing, we identified responsible gene of family 4794 with autosomal recessively nonsyndromic hearing loss (ARNSHL). We also used DNA from 56 Chinese familial patients with ARNSHL (autosomal recessive nonsyndromic hearing loss) and 108 ethnicity-matched negative samples to perform extended variants analysis.

Results

We identified MYO15A c.IVS25 + 3G > A and c.8375 T > C (p.V2792A) as the disease-causing mutations. Both mutations co-segregated with hearing loss in family 4794, but were absent in the 56 index patients and 108 ethnicity-matched controls.

Conclusions

Our results demonstrated that the hearing loss of family 4794 was caused by novel compound heterozygous mutations in MYO15A.

Novel compound heterozygous TMC1 mutations associated with autosomal recessive hearing loss in a Chinese family

Hereditary nonsyndromic hearing loss is highly heterogeneous and most patients with a presumed genetic etiology lack a specific diagnosis. It has been estimated that several hundred genes may be associated with this sensory deficit in humans. Here, we identified compound heterozygous mutations in the TMC1 gene as the cause of recessively inherited sensorineural hearing loss by using whole-exome sequencing in a family with two deaf siblings. Sanger sequencing confirmed that both siblings inherited a missense mutation, c.589G>A p.G197R (maternal allele), and a nonsense mutation, c.1171C>T p.Q391X (paternal allele), in TMC1. We also used DNA from 50 Chinese familial patients with ARNSHL and 208 ethnicity-matched negative samples to perform extended variants analysis. Both variants co-segregated in family 1953, which had the hearing loss phenotype, but were absent in 50 patients and 208 ethnicity-matched controls. Therefore, we concluded that the hearing loss in this family was caused by novel compound heterozygous mutations in TMC1.

Interaction of a calcium channel blocker with noise in cochlear function in guinea pig

CONCLUSIONS

Both nifedipine and noise exposure had damaging effects on cochlear function. These damaging effects were subtractive rather than additive, suggesting that calcium channel blockers may have a protective role in noise-induced hearing loss.

OBJECTIVE

We assessed the interaction of nifedipine, a calcium channel blocker, with noise in cochlear function by evaluating changes in the compound action potential (CAP) threshold after the administration of nifedipine with or without noise exposure.

METHODS

Eighty guinea pigs were randomly assigned to eight groups based on those with cochlear perfusion with nifedipine only (0, 0.15, 0.5, and 3 µM, groups 1-4) and noise exposure (groups 5-8). CAP thresholds were recorded using a round window electrode before and 120 min after cochlear perfusion.

RESULTS

Cochlear perfusion of different concentrations of nifedipine caused 2.5, 5.5, 28, and 21.5 dB SPL threshold shift, respectively, at 0, 0.15, 0.5, and 3 µM concentrations (groups 1-4). In comparison, the CAP thresholds after nifedipine perfusion with noise exposure were 43.5, 46.5, 20, and 21.5 dB SPL, respectively, in groups 5-8.

Aberrant internal carotid artery causing objective pulsatile tinnitus and conductive hearing loss

Aberrant internal carotid artery (ICA) in the middle ear is a rare, dangerous vascular anomaly and conservative follow-up was usually adopted in most reported cases. Here we report the case of an 8-year-old girl with symptoms of objective pulsatile tinnitus and conductive hearing loss in the right ear. Otoscopic examination, computed tomography, and conventional angiography were performed. An aberrant ICA combined with a 'third mobile window' was suspected preoperatively and confirmed at exploratory surgery of the middle ear. The aberrant ICA was treated, and the pulsatile tinnitus disappeared and hearing recovered after the surgery. This case suggests that surgery is practical to relieve troublesome tinnitus and hearing loss in appropriate cases with aberrant ICA.

Intraoperative CT-guided cochlear implantation in congenital ear deformity

CONCLUSIONS

Intraoperative computed tomography (iCT)-guided cochlear implantation is practical and effective for correct electrode placement in the cochlea of patients with congenital inner ear and/or complex middle ear malformation.

OBJECTIVES

The operation in patients with inner ear and/or complex middle ear malformation including abnormal facial nerve course is difficult. This study evaluated the efficacy of cochlear implantation under the guidance of iCT to insure correct electrode placement.

METHODS

This was a prospective interventional case series. Ten patients with severe to profound sensorineural hearing loss due to ear malformations were enrolled, and iCT was used to confirm the right placement of electrodes.

RESULTS

Intraoperative CT was performed three times in one patient, twice in two, and once in the others. Interruption of the surgical process for each iCT until resumption of surgery was 9.64 ± 0.63 min. iCT revealed incorrectly positioned cochlear implants in two patients, which were immediately corrected. There were no reoperations due to misplacement of electrodes. iCT helped locate the cochlea in the middle ear of one patient with an abnormal facial nerve course. The overall intervention rate based on iCT findings was 30%.

LEVEL OF EVIDENCE

level 4.

Rapid screening for the mitochondrial DNA C1494T mutation in a deaf population in China using real-time quantitative PCR

CONCLUSION

Real-time quantitative polymerase chain reaction (qPCR) with a TaqMan minor groove binding (MGB) probe is useful for large-scale screening for the C1494T mutation. The mitochondrial DNA(mtDNA) C1494T mutation has a low carrier frequency in Chinese patients with nonsyndromic hearing loss.

OBJECTIVE

To develop a simple, rapid, and reliable real-time qPCR assay based on TaqMan technology using a new MGB probe for detecting the mtDNA C1494T mutation directly, and to investigate the carrier frequency in nonsyndromic deaf Chinese subjects.

METHODS

A TaqMan-MGB probe was constructed. Peripheral blood samples were collected from 3133 nonsyndromic deaf patients and genomic DNA was extracted. A real-time qPCR using MGB probes (wild-type) in a single tube was used to detect the mtDNA C1494T mutation. The results were then compared to the DNA sequence of the PCR products.

RESULTS

A total of 13 of 3133 (0.4%) Chinese nonsyndromic hearing loss patients were C1494T-positive. The results of the TaqMan-MGB probe method were consistent with those of sequencing.

[Genetic counseling and instruction of marriage for deaf young people: study of 115 cases]

OBJECTIVE

To invesigate the molecular pathogenesis of deafness among the youth by means of genetic testing so as to provide pre-marriage genetic counseling and instruction for the deaf youth.

METHODS

217 deaf young people, 126 males and 91 females, aged 18.9 (16 - 26), from Yunnan and Guizhou provinces, underwent history taking, auditory testing, and collection of peripheral blood samples. Genomic DNA and mitochondrial DNA were extracted to undergo sequence analysis of the entire gene GJB2, common point mutation of SLC26A4 gene, and mutation of mtDNA A1555G. Genetic prediction and marriage instruction were provided to each subject based on these results.

RESULTS

Twenty-three of the 117 persons (10.5%), 13 males and 10 females, were mtDNA A1555G mutation carriers and they were instructed that they, their maternal relatives, and the offspring of the female carriers, should they be born, should strictly avoid the administration of amino glycoside antibiotics. Twenty eight of the 115 persons (12.9%), were confirmed to carry homozygous or compound GJB2 mutations, 5 individuals (2.3%) carried heterozygous GJB2 mutation, 19 (8.8%) carried homozygous or compound SLC26A4 mutations, and one (0.5%) carried heterozygous SLC26A4 mutation. The suggestion for them was to avoid getting married with deaf partners caused by the same deaf gene or with individuals carrying mutations in the same deaf gene. Meanwhile, suggestions such as avoiding aggressive exercises and head injury were provided to the deaf young people with SLC26A4 mutations.

CONCLUSION

Genetic testing can provide more accurate and useful genetic counseling and instruction to deaf young people for their partner selection and eugenics.

[Real-time Taqman probe technique system for detecting the MtDNA 1555 A > G mutation.]

OBJECTIVE

To establish a Real-time Taqman probe technique system to detect the mtDNA 1555A > G mutation in deaf population.

METHODS

Primers and Taqman probes for mtDNA 1555A > G mutation were designed and synthesized. The technique system for detecting mtDNA 1555A > G mutation using Real-time Taqman probes was established. Then the reliability of the technique was tested in 132 patients with severe to profound hearing loss who were detected for the mtDNA 1555A > G mutation by sequencing, Kit method and Real-time Taqman probe technique at the same time. Finally, the results by the above three ways were compared.

RESULTS

Thirty-two cases with mtDNA 1555A > G mutation were found by the technique of Real-time Taqman probe. These findings coincided with the results from sequencing and Kit method completely. Both the false positive rate and the false negative rate were zero.

CONCLUSIONS

The technique possesses the merits of accuracy, convenience, high sensitivity, high specificity and intuitionistic results, etc. Importantly, the Real-time Taqman probe technique only needs 1.5 hours to detect the 1555A > G mutation and it saves 4.5 hours for one reaction compared with the Kit method popularly used nowadays. The technique system of detecting mtDNA 1555A > G mutation is reliable. It's suitable for large-scale detecting and preventive diagnosis of mtDNA 1555A > G mutation.

Skeletal deterioration induced by RANKL infusion: a model for high-turnover bone disease

RANKL was administered continuously to rats for 28 days to investigate its potential as a disease model for the skeletal system. Bone turnover rates, bone material, structural and mechanical properties were evaluated. RANKL infusion caused overall skeletal complications comparable to those in high bone-turnover conditions, such as postmenopausal osteoporosis.

INTRODUCTION

RANKL is an essential mediator for osteoclast development. No study has examined in detail the direct skeletal consequences of excess RANKL on bone turnover, mineralization, architecture, and vascular calcification. We, therefore, administrated soluble RANKL continuously into mature rats and created a bone-loss model.

METHODS

Six-month-old Sprague-Dawley (SD) rats were assigned to three groups (n = 12) receiving continuous administration of saline (VEH) or human RANKL (35 microg/kg/day, LOW or 175 microg/kg/day, HI) for 28 days. Blood was collected routinely during the study. At sacrifice, hind limbs and aorta were removed and samples were analyzed.

RESULTS

High dose RANKL markedly stimulated serum osteocalcin and TRAP-5b levels and reduced femur cortical bone volume (-7.6%) and trabecular volume fraction (BV/TV) at the proximal tibia (-64% vs. VEH). Bone quality was significantly degraded in HI, as evidenced by decreased femoral percent mineralization, trabecular connectivity, and increased endocortical bone resorption perimeters. Both cortical and trabecular bone mechanical properties were reduced by high dose RANKL. No differences were observed in the mineral content of the abdominal aorta.

CONCLUSIONS

Continuous RANKL infusion caused general detrimental effects on rat skeleton. These changes are comparable to those commonly observed in high-turnover bone diseases such as postmenopausal osteoporosis.

Soluble RANKL induces high bone turnover and decreases bone volume, density, and strength in mice

Receptor activator for nuclear factor-kappa B ligand (RANKL) is an essential mediator of osteoclastogenesis. We hypothesized that administration of soluble RANKL to mice would result in high turnover and deleterious effects on both cortical and trabecular bone. For 10 days, 10-week-old C57BL/6J female mice (n = 12/group) were given twice-daily subcutaneous injections of human recombinant RANKL (0.4 or 2 mg/kg/day) or inert vehicle (VEH). Bone turnover was greatly accelerated by RANKL, as evidenced by the 49-84% greater levels of serum TRAP-5b (bone resorption marker) and 300-400% greater levels of serum alkaline phosphatase (bone formation marker). RANKL resulted in significantly greater endocortical bone erosion surface (79-83%) and periosteal bone formation rate (64-87%) vs. VEH. Microcomputed tomographic (microCT) analysis of the proximal tibia indicated a reduction in trabecular volume fraction (-84%) for both doses of RANKL. Cortical bone geometry and strength were also negatively influenced by RANKL. MicroCT analysis of the femoral diaphysis indicated significantly lower cortical bone volume (-10% to -13%) and greater cortical porosity (8-9%) relative to VEH. Biomechanical testing of the femur diaphysis revealed significantly lower maximum bending load (-19% to -25%) vs. VEH. Bone strength remained correlated with bone mass, independent of RANKL stimulation of bone turnover. These findings are consistent with the hypothesis that soluble RANKL could be an important etiologic factor in pathologic bone loss. RANKL also has potential utility as a model for studying the consequences of high bone turnover on bone quality and strength in animals.

[Features of nationwide distribution and frequency of a common gap junction beta-2 gene mutation in China]

OBJECTIVE

To determine the prevalence of a common GJB2 mutation in a big Chinese population of deaf children and the features of its distribution in regions all over the nation and to provide epidemiology data and expertise for genetic testing of deafness in China.

METHODS

The DNA samples of NSHI patients and normal controls were collected from different typical areas of China. The method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) with ApaI was used to determine the genotype of GJB2 235 site.

RESULTS

Totally 16.3% of patients carried at least one 235 delC mutant allele. Among them, 7.8% was homozygous and 8.5% was heterozygous. The prevalence of GJB2 235delC mutation in China was evident, and the significant difference of 235delC mutation frequency was found in sub-population from different areas and different ethnic groups.

CONCLUSIONS

Based upon the result of this screening as stated, Chinese NSHI patients appear to have 235delC frequency and the number of GJB2 related deafness was estimated to be huge. The testing of GJB2 235delC mutation would play an important role in genetic diagnosis and screening in China. As high as 15% of patients could be diagnosed as GJB2 caused deafness (bi-allelic mutation) only by means of this simple, fast and economic assay. In addition, patients were negative for 235delC mutation would be candidates for further mutational analysis of GJB2 or other deafness related genes.

[Sequencing of SLC26A4 exons 7 and 8 and hot spot mutation analysis in 1552 moderate to profound sensorineural hearing loss patients in China]

OBJECTIVE

To investigate the hot spot mutation of SLC26A4 gene and its incidence among patients with moderate to profound sensorineural hearing loss (SNHL) and to analyze the epidemiology of enlarged vestibular aqueduct syndrome in China.

METHODS

Peripheral blood samples were collected from 1,552 students of deaf and dumb school in 21 cities throughout China. The nationality distribution of the 1,552 students included Han (n = 1290), Uigur (n = 69), Hui (n = 37), Mongolian (n = 31), and Southwest minorities including Yi, Zhuang, Bai, Miao and other 14 nationalities (n = 125). The hot spot mutation IVS7-2A > G and other mutations in the SLC26A4 exons 7 and 8 with intron 7 were analyzed by direct sequencing.

RESULTS

Mutation in the SLC26A4 exons 7 and 8 or intron 7 were found in 199 students, of whom 83 carried IVS7-2A > G homozygous mutation, 114 carried IVS7-2A > G heterozygous mutation, and the other two carried two other kinds of mutation. Of the 1,552 cases, the percentage of cases carrying IVS7-2A > G mutation was 12.7% (197/1,552), and this percentage reached up to 14.3% in 1,290 cases of Han nationality, while in the 69 cases of Uigur nationality this ratio was 0. The prevalence rates of IVS7-2A > G mutation in Zhuozhou and Gaobeidian, Hebei province, and Anyang, Henan province, were 24.7% and 28.3% respectively, both significantly higher than the percentages of the whole China and other regions (all P < 0.05).

CONCLUSION

Hereditary SNHL caused by SLC26A4 mutations accounts for a high percentage in China. It is of great importance to screen SLC26A4 gene for making etiological diagnosis for deafness. Screening of the hot spot mutation of IVS7-2A > G is of advantage for large scale screening among patients with deafness.

[Patients suffered from enlarged vestibular aqueduct syndrome in Chifeng deaf and dumb school detected by Pendred's syndrome gene hot spot mutation screening]

OBJECTIVE

To investigate the incidence of hot spot mutation of PDS gene by genetic screening testing method in Chifeng City, Inner Mongolia. The feasibility and effectiveness of genetic screening method in finding enlarged vestibular aqueduct syndrome were confirmed by temporal bone CT scan.

METHODS

DNA were extracted from peripheral blood of 141 students of Chifeng Deaf and Dumb school. PDS IVS7-2 A-G mutation, the most common PDS mutation in Chinese population, was analyzed by direct sequencing for PDS exon 7, exon 8 with intron 7. The individuals found with homozygous or heterozygous PDS IVS7-2 A-G mutation were given further temporal CT scan, ultrasound scan of thyroid and thyroid hormone assays. The results of PDS genetic screening and temporal bone CT scan were compared with each other.

RESULTS

The sequencing results revealed twenty cases carrying PDS IVS7-2 A-G mutation, of whom nine cases were homozygous mutation and eleven cases were heterozygous mutation. Eighteen cases underwent temporal bone CT scan except two cases that left the school due to other health problem. Sixteen cases were confirmed to be enlarged vestibular aqueduct syndrome (EVAS) by CT scan and the shape and function of thyroid were clinically normal by ultrasound scan of thyroid and thyroid hormone assays, respectively.

CONCLUSIONS

The patients suffered from EVAS can be diagnosed by the screening for the PDS hot spot mutation which has unique advantage in epidemiologic study in large scale deaf population. The preliminary data of this study suggested relatively high incidence of EVAS in Chifeng area.

Progesterone primes zona pellucida-induced activation of phospholipase A2 during acrosomal exocytosis in guinea pig spermatozoa

We investigated, using guinea-pig spermatozoa as a model, whether phospholipase A2 (PLA2) is involved in progesterone or zona pellucida (ZP)-stimulated acrosomal exocytosis, if progesterone enhances ZP-induced activation of PLA2, and mechanisms underlying PLA2 regulation. Spermatozoa were capacitated and labeled in low Ca2+ medium with [14C]choline chloride or [14C]arachidonic acid, washed, and then exposed to millimolar Ca2+ and progesterone and/or ZP. Each agonist stimulated decrease of phosphatidylcholine (PC) and release of arachidonic acid and lysoPC, indicative of PLA2 activation. Aristolochic acid (a PLA2 inhibitor) abrogated lipid changes and exocytosis, indicating that these lipid changes are essential for exocytosis. Exposure of spermatozoa to submaximal concentrations of both progesterone and ZP resulted in a synergistic increase of arachidonic acid and lysoPC releases, and exocytosis, suggesting that, under natural conditions, both agonists interact to bring about acrosomal exocytosis. Progesterone-induced PLA2 activation appears to be mediated by a GABA(A)-like receptor, because bicuculline (a GABA(A) receptor antagonist) blocked arachidonic acid release and exocytosis. In agreement with this, GABA mimicked progesterone actions. ZP-induced activation of PLA2 seemed to be transduced via G(i) proteins because pertussis toxin blocked arachidonic acid release and acrosomal exocytosis. PLA2 may be regulated by PKC because progesterone- or ZP-induced release of arachidonic acid was blocked by the PKC inhibitors staurosporine or chelerythrine chloride. PLA2 could also be regulated by the cAMP-PKA pathway; inclusion of the PKA inhibitor 14-22 amide or H-89 led to a reduction in arachidonic acid release or exocytosis after progesterone or ZP. Taken together, these results suggest that PLA2 plays an essential role in progesterone or ZP-stimulated exocytosis with progesterone priming ZP action.

Zona pellucida induces activation of phospholipase A2 during acrosomal exocytosis in guinea pig spermatozoa

Phospholipase A(2) (PLA(2)) is activated in spermatozoa in response to progesterone and Ca(2+) ionophores, but to our knowledge, no study has yet reported zona pellucida (ZP)-induced activation of PLA(2). We investigated whether PLA(2) is involved in ZP-stimulated acrosomal exocytosis, if Ca(2+) is required for activation of PLA(2), and signal transduction pathways modulating PLA(2) using guinea pig sperm as a model. Spermatozoa were capacitated and labeled in low-Ca(2+) medium with [(14)C]choline chloride or [(14)C]arachidonic acid and were then exposed to millimolar Ca(2+) and various reagents and stimulated with ZP. Precapacitated spermatozoa exposed to millimolar Ca(2+) and stimulated with ZP experienced increases in arachidonic acid (AA) and lysophosphatidylcholine (lysoPC) levels and a parallel decrease in phosphatidylcholine level; these changes are indicative of PLA(2) activation. Simulation with ZP also led to acrosomal exocytosis in a high proportion of spermatozoa. Lipid changes and exocytosis were prevented if spermatozoa were exposed to aristolochic acid, a PLA(2) inhibitor, before treatment with ZP. Stimulation with ZP in medium without added Ca(2+) or in medium with millimolar Ca(2+) and EGTA or La(3+) resulted in no lipid changes or exocytosis. Pretreatment with pertussis toxin, a G(i) protein inhibitor, before stimulation with ZP blocked the release of AA and lysoPC as well as acrosomal exocytosis. Exposure of spermatozoa to the diacylglycerol (DAG) kinase inhibitor R59022 before ZP stimulation led to a significant increase in generation of lysoPC and exocytosis. Taken together, these results indicate very strongly that PLA(2) plays an essential role in ZP-induced exocytosis in spermatozoa, that PLA(2) activation requires Ca(2+) internalization, and that PLA(2) activation is regulated by signal transduction pathways involving G proteins and DAG.

Inhibition of hamster sperm acrosomal enzyme by gossypol is closely associated with the decrease in fertilization capacity

To elucidate the mechanism of sterility induced by gossypol, we studied the relationship between the activities of acrosomal enzymes and their fertilizing capacity in the hamster. The results showed that the ability of spermatozoa to penetrate into bovine cervical mucus, hyperactivated motility (HAM) and fertility in vivo were significantly inhibited when spermatozoa were exposed to gossypol (2.5 microg - 60 microg/mL) for 15 min in vitro. Also, following administration of gossypol (12.5 mg/kg/day) for 6 weeks, sperm motility, HAM and rate of fertilization in vitro by the hamster cauda epididymal spermatozoa were significantly decreased and the extracts of testis delayed dispersion of the cumulus oophorus cells, suggesting that hyaluronidase and other acrosomal enzymes might be inhibited by gossypol. In addition, acrosin and arylsulfatase activities were also markedly inhibited. These data show that the inhibition of acrosin and arylsulfatase activities is the main cause of gossypol-induced infertility. The inhibition was dependent upon gossypol dose and the duration of administration. Thus, the assay of acrosin and arylsulfatase activities may provide a useful tool for monitoring sterility induced by gossypol.