Etiology and Audiological Outcomes at 3 Years for 364 Children in Australia

Abstract

Hearing loss is an etiologically heterogeneous trait with differences in the age of onset, severity and site of lesion. It is caused by a combination of genetic and/or environmental factors. A longitudinal study to examine the efficacy of early intervention for improving child outcomes is ongoing in Australia. To determine the cause of hearing loss in these children we undertook molecular testing of perinatal “Guthrie” blood spots of children whose hearing loss was either detected via newborn hearing screening or detected later in infancy. We analyzed the GJB2 and SLC26A4 genes for the presence of mutations, screened for the mitochondrial DNA (mtDNA) A1555G mutation, and screened for congenital CMV infection in DNA isolated from dried newborn blood spots. Results were obtained from 364 children. We established etiology for 60% of children. One or two known GJB2 mutations were present in 82 children. Twenty-four children had one or two known SLC26A4 mutations. GJB2 or SLC26A4 changes with unknown consequences on hearing were found in 32 children. The A1555G mutation was found in one child, and CMV infection was detected in 28 children. Auditory neuropathy spectrum disorder was confirmed in 26 children whose DNA evaluations were negative. A secondary objective was to investigate the relationship between etiology and audiological outcomes over the first 3 years of life. Regression analysis was used to investigate the relationship between hearing levels and etiology. Data analysis does not support the existence of differential effects of etiology on degree of hearing loss or on progressiveness of hearing loss.

Impact of the presence of auditory neuropathy spectrum disorder (ANSD) on outcomes of children at three years of age

“…Molecular testing of newborn blood spots was completed for 32 (68%) children (Dahl et al, 2013). Families of 15 children (32%) declined permission for testing.…”

Hearing and neurodevelopmental outcomes for children with asymptomatic congenital cytomegalovirus infection: A systematic review

“…It is estimated that 40% to 58% of such children with symptomatic cCMV (ScCMV) experience long‐term sequelae, in particular hearing and neurodevelopmental impairment . Currently, cCMV is the most frequent non‐genetic cause of sensorineural hearing loss (SNHL) …”

“…Currently, cCMV is the most frequent non-genetic cause of sensorineural hearing loss (SNHL). [4][5][6][7] For the 90% of infected newborns who have clinically inapparent disease, their long-term outcomes are less clear. This is in part due to a lack of routine newborn screening for cCMV in a population where most infections will be asymptomatic and therefore not identified.…”

Congenital cytomegalovirus infection in pregnancy: a review of prevalence, clinical features, diagnosis and prevention

“…Congenital CMV infection is the leading infectious cause of hearing impairment in children, with 40–50% of infants born with symptomatic CMV infection and 7–15% of asymptomatic CMV‐infected newborns developing SNHL . Australian data show up to 10% of neonates failing universal hearing screening have congenital CMV, and in the absence of diagnosed genetic cause for SNHL, CMV is the likely cause . Importantly, these infants with SNHL may have other undiagnosed complications of CMV that may also benefit from early intervention …”