Congenital cytomegalovirus infection - a common cause of hearing loss of unknown aetiology

Aim: The aim of this study was to investigate the role of congenital cytomegalovirus (CMV) infection as a cause of various types of sensorineural hearing loss (SNHL) in a group of nonsyndromic children with otherwise unknown aetiology of hearing loss. Furthermore, the occurrence of combined congenital CMV infection and connexin 26 (Cx26) mutations was investigated. Methods: The dried blood spot (DBS) cards of 45 children with various degrees of hearing deficits and 46 children with severe/profound hearing loss were tested for CMV DNA with polymerase chain reaction (PCR) technique. The DBS cards of the 46 children with severe/profound hearing loss were also analysed for Cx26 mutations. Results: Of the 45 children with various degrees of hearing loss, nine were positive for CMV DNA (20%). The nine children represented severe/profound, mild and unilateral hearing loss. From the 46 children with severe/profound hearing loss, nine of 46 (20%) were positive for CMV DNA. In addition, three of the CMV DNA‐positive children were carriers of mutations of Cx26. Conclusion: Congenital CMV infection is a high risk factor in hearing impairment among children.     

GJB2基因及其诊断筛查技术研究进展

耳聋基因GJB2定位于13q11-q12,编码connexin26(CX26)蛋白.在常染色体隐形遗传的非综合征性耳聋中,有50%的患者存在着GJB2基因的突变,然而在不同种族中,GJB2基因的突变位点也是不同的.35delG是欧美人群主要的突变形式;突变位点167delT在犹太耳聋人群中多见;而在亚裔人群中,235delC突变占有极大的比例.由于GJB2基因在遗传性耳聋中的特殊地位,因此对于GJB2基因的诊断及筛查技术就显得尤为重要.在新生儿听力筛查基础上,融入耳聋易患基因分子水平筛查,在早期发现和干预先天性听力损失方面发挥着重要作用.     

The mutation 35delG of the gene of the connexin 26 is a frequent cause of autosomal-recessive non-syndromic hearing loss in Morocco]

Mutations of the connexin 26 gene, GJB2, are the most common cause of non syndromic autosomal-recessive hearing loss. One of the GJB2 mutations, the 35delG, is recurrent in European and Mediterranean populations with allelic frequency of at least 70% in patients with hearing loss caused by GJB2 impairment. OBJECTIVES: To determine the prevalence of the 35delG mutation in non-syndromic autosomal-recessive deafness in Morocco. PATIENTS AND METHODS: We looked for the 35delG mutation among 25 non-related Moroccan children suffering from an autosomal recessive hearing loss. A screening for GJB2 mutations, and then a search for GJB6 deletions were carried out among patients who do not bear the 35delG. RESULTS: Twelve patients were homozygous for the 35delG mutation. This mutation was responsible for almost half of the hearing loss among our patients (48%). There was no other GJB2 or GJB6 mutation among 13 patients. CONCLUSION: This study underlines the advantages of a systematic search for this mutation among deaf children when environmental causes are considered irrelevant. The identification of this genetic anomaly signs the etiologic diagnosis of deafness, which allows a relevant genetic advice, and a better treatment of patients.     

The R245X mutation of PCDH15 in Ashkenazi Jewish children diagnosed with nonsyndromic hearing loss foreshadows retinitis pigmentosa

Usher syndrome is a frequent cause of the combination of deafness and blindness due to retinitis pigmentosa (RP). Five genes are known to underlie different forms of Usher syndrome type I (USH1). In the Ashkenazi Jewish population, the R245X mutation of the PCDH15 gene may be the most common cause of USH1 (Ben-Yosef T, Ness SL, Madeo AC, Bar-Lev A, Wolfman JH, Ahmed ZM, Desnick RK, Willner JP, Avraham KB, Ostrer H, Oddoux C, Griffith AJ, Friedman TB N Engl J Med 348: 1664-1670, 2003). To estimate what percentage of Ashkenazi Jewish children born with profound hearing loss will develop RP due to R245X, we examined the prevalence of the R245X PCDH15 mutation and its carrier rate among Ashkenazi Jews in Israel. Among probands diagnosed with nonsyndromic hearing loss not due to mutations of connexin 26 (GJB2) and/or connexin 30 (GJB6), and below the age of 10, 2 of 20 (10%) were homozygous for the R245X mutation. Among older nonsyndromic deaf individuals, no homozygotes were detected, although one individual was heterozygous for R245X. The carrier rate of the R245X mutation among the normal hearing Ashkenazi population in Israel was estimated at 1%. Ashkenazi Jewish children with profound prelingual hearing loss should be evaluated for the R245X PCDH15 mutation and undergo ophthalmologic evaluation to determine whether they will develop RP. Rehabilitation can then begin before loss of vision. Early use of cochlear implants in such cases may rescue these individuals from a dual neurosensory deficit.     

Congenital cytomegalovirus infection: a cause of sensorineural hearing loss.

Prospective studies have suggested that about 108 children with congenital cytomegalovirus (CMV) infection and bilateral sensorineural hearing loss are born each year in England and Wales; this represents about 12% of all children with congenital sensorineural hearing loss. Over a nine year period 1644 children aged between 6 months and 4 years who were attending the Nuffield Hearing and Speech Centre were screened for CMV infection. The prevalence of CMV in the urine of children with sensorineural hearing loss but no immediate family history of deafness was nearly twice that (13%) found in other children with impaired hearing and those with normal hearing (7%). These findings indicate the importance of CMV as a cause of hearing loss.     

Nonsyndromic sensorineural deafness--analysis of etiology in relatives

We present the results of complex clinical examination of children affected with sensorineural hearing loss. The siblings (minimum two) were born from unaffected parents and came from twelve families. Molecular studies confirmed genetic background of hearing loss in 6 families and enabled identification of GJB2 mutations in investigated probants.     

先天性巨细胞病毒感染抗病毒治疗的效果和安全性观察

目的：观察更昔洛韦（GCV）和（或）缬更昔洛韦（VGCV）治疗先天性巨细胞病毒（ CMV）感染患儿的疗效和不良反应。 方法：回顾性纳入2012年3月1日至2017年5月31日在复旦大学附属儿科医院（我院）新生儿科住院、确诊为先天性CMV感染的患儿,随访至2017年12月31日。从病史资料中提取患儿的一般资料,抗CMV治疗的药物和疗程,新生儿期及1、 3和6月龄的肝脾触诊检查结果、胆红素和肝功能检查指标、CMV抗体和DNA检测结果、颅脑MRI、眼底检查结果和听力检测结果,治疗期间药物的不良反应。根据抗病毒治疗与否以及疗程长短分组,比较各组的临床特征和治疗反应。 结果：28例先天性CMV感染患儿进入本文分析,其中早产儿11例,男17例;无症状/轻度症状9例,未予抗病毒治疗;中重度症状19例,GCV和（或）VGCV治疗≤6周组11例,治疗6个月组8例。①6月龄时,除1例胆汁酸轻度升高外27例中枢神经系统以外的症状和体征、胆红素、肝功能和血常规均恢复正常。②无症状／轻度症状组1例在6月龄时出现左侧听力中度损失。治疗≤6周组中,2例CMV相关眼底病变于1月龄时消失; 颅脑MRI异常信号和听力损失者各5例,6月龄时分别有3例和2例无改善。治疗6个月组中,4例先天性CMV感染相关视网膜病变在随访中均消失;3例头颅MRI异常信号者和7例有听力损失者,6月龄时分别有2例和1例无改善。③治疗≤6周组和治疗6个月组在6月龄时中枢神经系统病变改善情况差异无统计学意义。④治疗过程中未发现与GCV和VGCV应用相关的粒细胞减少和肝功能异常。 结论：抗病毒治疗能改善感音神经性耳聋和脉络膜视网膜炎,GCV和（或）VGCV≤6周与6个月的治疗效果相近;建议对无临床症状先天性CMV感染患儿行眼底检查、脑干诱发电位和头颅MRI检查。     

The outcome in children with congenital cytomegalovirus infection. A longitudinal follow-up study

Infants with congenital cytomegalovirus (CMV) infection were identified through urine cultures of 15,212 consecutive neonates and studied prospectively to determine whether their neurodevelopmental and audiologic status was different from that of matched uninfected control subjects. Of 64 children with congenital CMV infection, three died, 11 could not be located for follow-up, one had quadriplegic cerebral palsy, and seven had varying degrees of sensorineural hearing loss. All matched control subjects were normal neurologically, and none of them had sensorineural hearing impairment. The Stanford-Binet test revealed scores within the normal range, at 3 and 5 years of age, for both children with CMV infection and matched control subjects, as did the preschool assessment (Wide Range Achievement Test) in children older than 5 years. However, in children with CMV infection, the home environment was less stimulating, discipline and punishment were more readily implemented, and behavioral problems were significantly greater than in the matched control subjects.     

Hearing loss in children with congenital cytomegalovirus infection born to mothers with preexisting immunity

OBJECTIVE: To define hearing outcomes in children with congenital cytomegalovirus (CMV) infection born to mothers with non-primary CMV infection. STUDY DESIGN: A cohort of 300 children with congenital CMV infection identified by newborn virologic screening at the University of Alabama Hospital and a private community hospital in which the type of maternal infection could be classified constituted the study population. Maternal infections were categorized by analyzing serum samples. Children were followed prospectively and underwent serial audiologic evaluations. RESULTS: The frequency of hearing loss was not different between children born to mothers with non-primary infection (10%) and those with primary infection (11%). Significantly more children in the primary infection group had progressive and severe/profound hearing loss compared with children in the non-primary group. The frequency of bilateral, delayed onset, high-frequency, and fluctuating hearing loss was not different between the 2 groups. The mean age of diagnosis of hearing loss was 39 +/- 53 months for children born to mothers with non-primary infection and 13 +/- 21 months for the primary infection group (P = .16). CONCLUSIONS: Maternal preexisting seroimmunity to CMV does not provide complete protection against hearing loss in infants with congenital CMV infection.     

新生儿重症监护病房新生儿耳聋基因致病变异携带者筛查的横断面调查

背景：我国耳聋发病率高与耳聋基因致病变异的携带率高有关,目前缺乏对NICU新生儿耳聋基因致病变异携带者的筛查数据。 目的：调查NICU新生儿中耳聋基因GJB2 和SLC26A4致病变异的携带率。 设计：横断面研究。 方法：纳入2016年1月至2021年12月在复旦大学附属儿科医院NICU住院、入院日龄≤28 d,且出院前完成高通量测序的新生儿,排除生后耳聋相关基因诊断阳性者。从病历系统中截取患儿的性别、胎龄、出生体重;从测序数据库中提取GJB2 基因和SLC26A4基因的检测结果、患儿人类表型标准用语信息。携带率（%）=杂合致病或可能致病（P/LP）变异例数/总研究对象人数。检索PubMed、Embase和万方数据库,纳入既往报道中国NICU人群、新生儿人群和孕妇人群中GJB2 基因和/或SLC26A4基因P/LP变异携带情况的文献,并行复习。 主要结局指标：GJB2 基因和SLC26A4基因的P/LP变异携带率。 结果：纳入14 924例新生儿,男8 587例（57.5%）,女6 337例,胎龄（35.6±3.7）周,出生体重（2 711.7±887.1）g。携带GJB2 基因P/LP变异的患儿2 009例（13.462%）,共检出18种杂合P/LP变异,其中c.109G>A最常见（10.902%）,其次为c.235del（1.749%）、c.299_300del（0.409%）、c.176_191del（0.154%）、c.508_511dup（0.074%）和c.257C>G（0.034%）。携带SLC26A4基因P/LP变异的患儿305例（2.044%）,共检出31种杂合P/LP变异,携带率最高的6种依次为c.919-2A>G（1.139%）、c.2168A>G（0.181%）、c.1226G>A（0.100%）、c.1229C>T（0.094%）、c.1174A>T（0.080%）和c.1003T>C（0.047%）。 结论：建议将GJB2 基因上的c.109G>A、c.508_511dup和c.257C>G以及SLC26A4基因的c.1003T>C位点纳入NICU新生儿耳聋基因致病变异携带者筛查。     

Congenital and postnatally acquired cytomegalovirus infections: long-term follow-up

To determine long-term outcome of children with inapparent congenital cytomegalovirus infection, an assessment of congenitally infected children observed since birth was undertaken. Children with early postnatal acquisition of CMV infection were also evaluated. Cognitive, behavioral, neurologic, audiometric, and speech and language evaluations were performed in 48 patients, including 17 congenitally infected children, 10 children with postnatal infection, and 21 uninfected control subjects. Mean IQ of the three groups of children did not differ significantly. Behavioral, neurologic, speech and language examinations similarly failed to distinguish differences among the three groups. Audiologic abnormalities were present in four congenitally infected children, including one child with a severe unilateral sensorineural loss; in none of the children was hearing loss functionally significant. No hearing abnormalities were detected in postnatally infected children. Although inapparent CMV infection can result in audiologic sequelae, the continued lack of cognitive, behavioral, and neurologic sequelae in these school-age children reemphasizes the need to focus attention on prevention of primary maternal CMV infection to avoid the potentially devastating effects of intrauterine CMV infection.     

Congenital cytomegalovirus infection: association between virus burden in infancy and hearing loss

OBJECTIVE: To determine the relationship between the virus burden in infancy and hearing loss in congenital CMV infection. STUDY DESIGN: A cohort of 76 infants with congenital cytomegalovirus (CMV) infection identified by means of newborn virologic screening was monitored for outcome. The amount of infectious CMV was analyzed in urine specimens obtained during early infancy. Peripheral blood (PB) samples obtained during early infancy were available from 75 children and CMV DNA was quantitated with a real-time quantitative polymerase chain reaction. RESULTS: Infants with clinical abnormalities at birth (symptomatic congenital CMV infection) had higher amounts of CMV in urine (P = .005) and CMV DNA in PB (P = .001) than infants with no symptoms. Eight children with and 4 children without symptoms had hearing loss. Among children without symptoms, those with hearing loss had a significantly greater amount of CMV in urine (P = .03) and PB virus burden (P = .02) during infancy than those with normal hearing. Infants with < 5 x 10(3) pfu/mL of urine CMV and infants with < 1 x 10(4) copies/mL of viral DNA in PB were at a lower risk for hearing loss. CONCLUSION: In children with asymptomatic congenital CMV infection, hearing loss was associated with increased amounts of urine CMV and PB CMV DNA during early infancy.     

Newborn hearing screening: will children with hearing loss caused by congenital cytomegalovirus infection be missed?

OBJECTIVE: To predict whether universal newborn auditory screening will identify most infants with sensorineural hearing loss (SNHL) caused by congenital cytomegalovirus (CMV) infection. STUDY DESIGN: A cohort of 388 children born between 1980 and 1996 at one hospital and identified during the newborn period as having congenital CMV infection received repeated hearing evaluations to assess whether hearing loss had occurred. RESULTS: SNHL was detected in 5.2% of all infants at birth. Late-onset SNHL occurred among the children throughout the first 6 years of life. By the age of 72 months, the cumulative incidence of SNHL was 15.4% in the cohort. Children with clinically apparent disease at birth had significantly more SNHL than children without any apparent disease (22.8% vs 4.0% at 3 months and 36.4% vs 11.3% at 72 months of age). CONCLUSIONS: Universal screening of hearing in neonates will detect less than half of all SNHL caused by congenital CMV infection. Because most infants with congenital CMV infection are without symptoms at birth, these children are unlikely to be recognized as being at risk for SNHL and will not receive further hearing evaluations to detect late-onset hearing loss. A combined approach of universal screening of neonates for hearing, as well as for detection of congenital CMV infection, needs to be considered.     

Connexin 26 <Emphasis Type="Italic">(GJB2)</Emphasis> Mutations Associated with Non-Syndromic Hearing Loss (NSHL)

Objective

To determine the prevalence and spectrum of Connexin 26 (GJB2) mutations in pre-lingual non-syndromic hearing loss (NSHL) patients in authors’ centre and to review the data of Indian patients from the literature.

Methods

Sanger sequencing of entire coding region contained in single exon (Exon 2) of GJB2 gene in 15 patients of NSHL.

Results

GJB2 mutations were found in 40% (6/15) of NSHL patients, out of which mono-allelic were 33.3% (2/6). Bi-allelic GJB2 mutations were identified in 4 of 6 patients. Most common GJB2 mutation identified was c.71G?>?A(p.W24X), comprising 30% of the total GJB2 mutant alleles. Six studies involving 1119 patients with NSHL were reviewed and 4 of them have reported c.71G?>?A(p.W24X) as the commonest mutation while 2 studies found c.35delG as the commonest. GJB2 mutations accounted for 10.9%–36% cases of NSHL. Sixteen other mutations in GJB2 gene were reported in Indian patients out of which 6 mutations other than c.71G?>?A(p.W24X) viz., c.35delG, c.1A?>?G(p.M1V), c.127G?>?A(p.V43 M), c.204C?>?G(p.Y86X), c.231G?>?A(p.W77X) and c.439G?>?A(p.E147K) were identified in the present study.

Conclusions

Connexin 26 (GJB2) mutations are responsible for 19.4% of NSHL in Indian population. The c.71G?>?A(W24X) and c.35delG were the most prevalent GJB2 mutations accounting for 72.2% (234 of 324 total mutated alleles from 7 studies) and 15.4% (50 of 324 total mutated alleles from 7 studies) respectively. Thus, screening of these two common mutations in GJB2 gene by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) would greatly help in providing easy genetic diagnosis and help in genetic counseling of the families with NSHL.

     

A wider role for congenital cytomegalovirus infection in sensorineural hearing loss

BACKGROUND: Diagnostic problems in identifying congenital infection cases in infancy have thus far impaired the assessment of the role of congenital cytomegalovirus (CMV) infection in the etiology of sensorineural hearing loss (SNHL). OBJECTIVE: To estimate the impact of congenital infection in children with SNHL by detection of CMV DNA in stored samples of neonatal dried blood (dried blood spots test). METHODS: The Guthrie cards of 130 children with hearing loss >40 dB hearing loss were retrieved from the regional screening center. CMV DNA was extracted by thermal shock and amplified by PCR. RESULTS: The percentage of SNHL cases attributable to congenital CMV infection was 10% (9 of 87) in infants whose SNHL had been diagnosed in their first 2 months of life and 34.2% (13 of 38) in children with deafness of unidentified cause that was diagnosed in early childhood. In the latter group 42.7% (12 of 28) of the children with a hearing loss of >70 dB were CMV-positive. CONCLUSIONS: The results suggest that congenital CMV infection has a more relevant role in the etiology of SNHL than previously reported. The data obtained in both groups suggest that 20 to 30% of all deafness cases are caused by CMV. The percent of congenital CMV cases alone appears to account for all the cases previously attributed to all congenital infections. More than 40% of deafness cases with an unknown cause, needing rehabilitation, are caused by congenital CMV.     

Identification of SLC26A4 gene mutations in Iranian families with hereditary hearing impairment

Mutations in the SLC26A4 gene at the DFNB4 locus are responsible for Pendred syndrome and non-syndromic hereditary hearing loss (DFNB4). This study included 80 nuclear families with two or more siblings segregating presumed autosomal recessive hearing loss. All deaf persons tested negative for mutations in GJB2 at the DFNB1 locus and were, therefore, screened for autozygosity by descent (ABD) using short tandem repeat polymorphisms (STRPs) that flanked SLC26A4. In 12 families, homozygosity for STRPs suggested possible ABD in this genomic region. Affected individuals in five families had a positive perchlorate discharge test. Sequence analysis of SLC26A4 identified ten mutations in eight families (T420I, 1197delT, G334V, R409H, T721M, R79X, S448L, L597S, 965insA and L445W), of which, four are novel (T420I, G334V, 965insA and R79X). These results imply that Pendred syndrome is the most prevalent form of syndromic hereditary hearing loss in Iran.     

Treatment of children with congenital cytomegalovirus infection with ganciclovir

BACKGROUND: Congenital cytomegalovirus (CMV) infection affects approximately 1% of live births in the US. Ten percent of these infants have symptoms at birth and another 10 to 15% acquire hearing loss or developmental problems. Congenital CMV is the most common cause of nonhereditary sensorineural hearing loss in children, and progressive hearing loss is common. To arrest the natural progression of congenital CMV, children referred to our center were treated with a prolonged course of ganciclovir. METHODS: Medical records of children with congenital CMV who were treated with ganciclovir were reviewed to tabulate their presenting symptoms, duration of treatment, audiologic and developmental assessments and complications. RESULTS: We treated nine children with symptomatic CMV with iv ganciclovir at a median age of 10 days (range, 3 days to 11 months). Findings at diagnosis included microcephaly (five of nine); petechiae (five of nine); thrombocytopenia (seven of nine); and intracranial calcifications (six of eight). Hearing loss was noted before therapy in five of nine. The median duration of iv and subsequent oral ganciclovir was 1 year and 0.83 year, respectively. Median follow-up was 2 years (range, 1 to 7 years). No child had progression of hearing loss; improvement occurred in two. Seven children had at least one complication of ganciclovir therapy: central venous catheter/site infection (six); catheter malfunction (three); and neutropenia (one). CONCLUSION: Of nine children none treated with ganciclovir for congenital CMV had detectable progressive hearing loss. Complications associated with iv therapy occurred frequently. Currently available oral analogues of ganciclovir may facilitate earlier and more prolonged therapy for children with symptomatic congenital CMV and should be subjected to randomized controlled trials.     

Postnatally acquired cytomegalovirus infection via breast milk: effects on hearing and development in preterm infants

BACKGROUND: In preterm infants there is a high risk of transmission of cytomegalovirus (CMV) via breast milk from seropositive mothers with reactivation of the virus during lactation. There is little information about the long term sequel of early postnatally acquired CMV infection in pre-term infants. This study aimed to investigate whether there was an increased frequency of impaired neurodevelopmental outcome and sensorineural hearing loss in preterm infants with postnatally acquired CMV infection through transmission by CMV-positive breast milk. METHODS: Twenty-two preterm infants [median birth weight, 1020 g (range, 600 to 1870 g); median gestational age, 27.6 weeks (range, 23.6 to 32 weeks] with early postnatally acquired CMV infection by breast-feeding (onset of viruria between Days 23 and 190 postnatally) were compared with 22 CMV-negative preterm infants individually matched for gestational age, birth weight, gender, intracranial hemorrhage and duration of ventilation. At 2 to 4.5 years of age, follow-up assessments were conducted consisting of neurologic examination, neurodevelopmental assessment and detailed audiologic tests. RESULTS: None of the children had sensorineural hearing loss. There was no difference between the groups with regard to neurologic, speech and language or motor development. CONCLUSION: The results of this study suggest that early postnatally acquired CMV infection via CMV-positive breast milk does not have a negative effect on neurodevelopment and hearing in this group of patients. Because we studied a small number of infants, further follow-up studies are warranted in preterm infants with early postnatally acquired CMV infection.     

The principles of molecular diagnosis of recessive forms of prelingual non-syndromic hearing loss

The GJB2 gene defects are the most frequent cause of autosomal recessive non-syndromic hearing loss (DFNB1). Epidemiological data suggest that 35delG is the most prevalent mutation found in 88% of mutated alleles. Another mutations - 313del14 was found in 7% of mutated alleles. The other mutations were identified only in single families. Following the analysis of distribution of GJB2 mutations in the Polish population we propose an algorithm for molecular diagnosis of DFNB1. We propose to screen all patients affected with prelingual non-syndromic deafness for 35delG mutation using ASO or multiplex AS-PCR methods. The presence of 35delG on two alleles confirms DFNB1. The identification of heterozygous 35delG mutation requires additional GJB2 analysis including 313del14 mutation detection and en exon 2 direct sequencing. To determinate the frequency of digenic (GJB2/GJB6) background of DFNB we screened 17 patients with heterozygous 35delG mutation for deletion of 342 kb in GJB6 gene. No such mutation was detected in the analyzed group.