Education in the genetics of hearing loss: A survey of early hearing detection and intervention programs

Abstract

Purpose: Permanent hearing loss at birth or in early childhood is common and has many genetic and environmental causes. Advances in the identification and characterization of genetic forms, combined with the early identification of children through the implementation of state-based Early Hearing Detection and Intervention programs suggests the need for education about the causes of hearing loss among professionals who work in these programs. Key Words: genetics education, hearing loss, early hearing detection and interventionHearing loss (HL) is an etiologically heterogeneous trait with many recognized genetic and environmental causes. 1,2 The incidence of profound deafness at birth is about 0.8 per 1,000 live births and another 1-2 infants/1,000 births have a lesser but clinically significant loss of 30 dB HL or greater in at least one ear. Despite the establishment of newborn hearing screening programs throughout the United States and around the world, comparable estimates of the incidence and specific causes of deafness remain elusive because of major differences in screening and testing protocols, equipment, screening and diagnostic criteria, variable follow-up for audiologic confirmation, the recognition that some forms of pre-lingual deafness are not expressed at birth, and the lack of an etiologic focus in most screening programs. 3 Approximately 60% of hearing loss present at birth or beginning within the first few months of life results from alterations in one or more of an estimated 400 genes involved in the determination of the structure and function of the organ of hearing. 4 More than 100 loci for non-syndromic deafness have now been mapped and at least 40 of the genes at these loci have been cloned. 5 However, despite the large number of genes that are capable of causing deafness, mutations involving a single gene at the DFNB1 locus, GJB2, which encodes the connexin 26 protein, account for approximately 30 -40% of all profound, congenital or early-onset hereditary deafness in the United States. 6,7 A 309 kb deletion of GJB6 has been shown to cause deafness when present in the homozygous state or in trans with GJB2 mutations. 8,9 GJB6 is a functionally related gene telomeric to GJB2 at the DFNB1 locus. GJB6 encodes the connexin 30 protein. Mutation screening for GJB2 and GJB6 is now widely available for clinical testing. Similarly, diagnostic DNA testing for some less common forms of syndromic and non-syndromic deafness is already available and the number of forms of hereditary deafness for which tests are available is likely to increase in the future. Interestingly, based on a recent study in the United Kingdom, it has been suggested that screening for genes other than GJB2 in Caucasian children produces a very low yield and is not cost-effective. 10 Early diagnosis and intervention (before six months of age) can have a dramatic effect on improving the communication skills and the educational achievement of children with hearing loss. 11,12 At present, all states and territories in the US have eit...

Factors influencing parental decision about genetics evaluation for their deaf or hard-of-hearing child

“…About the same time, the American College of Medical Genetics (ACMG) published a recommendation that all children with confirmed hearing loss be referred for genetics evaluation and counseling 14, a statement echoed by the JCIH 15, 16. Newborn hearing screening has since become widely available in the United States and other countries 17–19, however, widespread involvement of genetics service providers within the early hearing detection and intervention programs is lagging 20, 21.…”