The prevalence and risk factors for congenital hearing loss in neonates: A birth cohort study based on CHALLENGE study

A novel copy number variant in the murine Cdh23 gene gives rise to profound deafness and vestibular dysfunction

Hearing loss is the most common congenital sensory deficit worldwide and exhibits high genetic heterogeneity, making molecular diagnoses elusive for most individuals. Detecting novel mutations that contribute to hearing loss is crucial to providing accurate personalized diagnoses, tailored interventions, and improving prognosis. Copy number variants (CNVs) are structural mutations that are understudied, potential contributors to hearing loss. Here, we present the Abnormal Wobbly Gait (AWG) mouse, the first documented mutant exhibiting waltzer-like locomotor dysfunction, hyperactivity, circling behaviour, and profound deafness caused by a spontaneous CNV deletion in cadherin 23 (Cdh23). We were unable to identify the causative mutation through a conventional whole-genome sequencing (WGS) and variant detection pipeline, but instead found a linked variant in hexokinase 1 (Hk1) that was insufficient to recapitulate the AWG phenotype when introduced into C57BL/6J mice using CRISPR-Cas9. Investigating nearby deafness-associated genes revealed a pronounced downregulation of Cdh23 mRNA and a complete absence of full-length CDH23 protein, which is critical for the development and maintenance of inner ear hair cells, in whole head extracts from AWG neonates. Manual inspection of WGS read depth plots of the Cdh23 locus revealed a putative 10.4 kb genomic deletion of exons 11 and 12 that was validated by PCR and Sanger sequencing. This study underscores the imperative to refine variant detection strategies to permit identification of pathogenic CNVs easily missed by conventional variant calling to enhance diagnostic precision and ultimately improve clinical outcomes for individuals with genetically heterogenous disorders such as hearing loss.

Leading Risk Factors for Congenital Deafness in the Context of Universal Neonatal Screening: Our Observations in a Four-Year Retrospective Study

It has been demonstrated that universal hearing neonatal screening (UHNS) is efficient at providing early diagnosis and rehabilitation for deafness. The risk factors of deafness in children have been identified, but less specifically in those diagnosed after UHNS. In this study, we aim to study these factors in infants who were referred after screening and to compare our experience to recent data. We studied infants referred to our department for diagnosis after screening between January 2018 and December 2021. Their medical history and neonatal hearing risk factors were assessed. Associations between factors were also analyzed. Sixty-six infants were included. A family history of deafness (47%), syndromic deafness (41%), intrauterine growth retardation or prematurity (19.7%), and prolonged NICU admission (18%) were the most observed factors. When analyzing according to these associations, family history of deafness and syndromic cases remained the most prevalent factors (74%), while only five cases (7.8%) presented with other neonatal risk factors only. The majority of congenital hearing loss cases are observed in infants with suspected genetic deafness. Parental counseling, the diagnostic pathway, as well as the healthcare system should be adapted according to these risk factors.

Risk factors and outcomes in patients with cochlear nerve deficiency

INTRODUCTION

Cochlear nerve deficiency (CND) is a cause of sensorineural hearing loss made by radiologic criteria. There is sparse literature involving audiological outcomes and cochlear implantation (CI) success in patients with CND.

METHODS

A retrospective chart review of all patients with sensorineural hearing loss at a tertiary children's hospital from 2000 to 2020 was conducted. Patients with CND on radiographic imaging were included and categorized as hypoplastic, aplastic, or indeterminate.

RESULTS

In this study, 53 patients were identified with CND, totaling 70 ears. Of the 53 patients, 30 (56.6 %) were male, 8 (16.0 %) had a family history of childhood hearing loss, 6 (11.3 %) were born preterm, and 11 (23.4 %) required neonatal intensive care admission. The median maternal age was 29 years old [IQR: 27, 35], and 8 (15 %) patients were born to mothers with diabetes. Of the 70 ears, 49 (70 %) utilized conventional hearing aids, 12 (17.1 %) utilized a bone-anchored hearing aid, and 10 (14.3 %) underwent CI. Of the 10 ears implanted, 4 (40 %) ears had nerves classified as hypoplastic, 3 (30 %) as aplastic, and 3 (30 %) as indeterminate. Improvement in pure tone averages compared to preoperative testing was demonstrated in 8 (80 %), and 6 (60 %) displayed improved speech awareness thresholds.

CONCLUSION

This study demonstrates that there may be an association between CND and maternal diabetes and NICU admission. There are variable results with hearing amplification options in patients with CND, and further research is needed to better describe the role of CI, bone-anchored hearing aids and conventional hearing aids in patients with CND.

Analysis of audiological outcomes of children referred from a universal newborn hearing screening program over 9 years in Beijing, China

Universal newborn hearing screening (UNHS) and audiological diagnosis are crucial for children with congenital hearing loss (HL). The objective of this study was to analyze hearing screening techniques, audiological outcomes and risk factors among children referred from a UNHS program in Beijing. A retrospective analysis was performed in children who were referred to our hospital after failing UNHS during a 9-year period. A series of audiological diagnostic tests were administered to each case, to confirm and determine the type and degree of HL. Risk factors for HL were collected. Of 1839 cases, 53.0% were referred after only transient evoked otoacoustic emission (TEOAE) testing, 46.1% were screened by a combination of TEOAE and automatic auditory brainstem response (AABR) testing, and 1.0% were referred after only AABR testing. HL was confirmed in 55.7% of cases. Ears with screening results that led to referral experienced a more severe degree of HL than those with results that passed. Risk factors for HL were identified in 113 (6.1%) cases. The main risk factors included craniofacial anomalies (2.7%), length of stay in the neonatal intensive care unit longer than 5 days (2.4%) and birth weight less than 1500 g (0.8%). The statistical data showed that age (P < 0.001) and risk factors, including craniofacial anomalies (P < 0.001) and low birth weight (P = 0.048), were associated with the presence of HL. This study suggested that hearing screening plays an important role in the early detection of HL and that children with risk factors should be closely monitored.

Maternal and child predictors associated with loss to follow-up in the newborn hearing screening program: a cohort study in maternity hospitals in northeastern Brazil

PURPOSE

Analyze maternal and child predictors associated with loss to follow-up in the newborn hearing screening program at maternity hospitals in northeastern Brazil.

METHODS

Retrospective cohort study, including secondary data from infants (n=604) referred to the newborn hearing screening program in two maternity hospitals for monitoring and/or diagnosis. The predictors evaluated included socioeconomic factors, such as maternal age, marital status, income, schooling, place of residence, number of children and number of prenatal visits. In addition, maternal and child health factors, such as smoking and drug intake during pregnancy, consanguinity, congenital infections, craniofacial malformations, use of ototoxic drugs, syndromes and a history of hearing loss in the family. Statistical analysis was performed based on binary logistic regression models, using the stepwise method.

RESULTS

The logistic regression model containing the number of prenatal visits and the history of hearing loss in the family was significant [χ2(2) =34.271; p<0.001]. The number of prenatal visits (OR = 2.343; 95% CI = 1.626 - 3.376) and family history of hearing loss (OR = 2.167; 95% CI = 1.507 - 3.115) were significant predictors. The other predictors were not significant.

CONCLUSION

The results reveal that newborns whose mothers had ≤ 5 prenatal visits and those with a family history of hearing loss increased their likelihood of loss to follow-up by 2.3 and 2.1 times, respectively. It is important to provide subsidies for public health improvements in order to help advise, guide and educate mothers, especially during prenatal care.