The American College of Medical Genetics and Genomics (ACMG) has announced the release of a new clinical practice resource that will help guide the treatment of patients with hearing loss: “Clinical Assessment and Etiological Diagnosis of Hearing Loss: A Resource of Clinical Practice from the American College of Medical Genetics and Genomics.
According to the ACMG announcement, the clinical practice resource offers information on the frequency, causes and presentations of hearing loss, and suggests approaches for the clinical and genetic evaluation of people who are deaf and hard of hearing aimed at identifying etiological diagnosis and to provide information and effective patient education and genetic counselling.
Two to three in every 1,000 children born in the United States are deaf or have hearing loss (HL) severe enough to affect speech and language development. Early intervention has been shown to be effective in facilitating speech and language development. As a result, Newborn Hearing Screening (NBHS), which began in 2001, is now mandatory across the United States. However, not all childhood HL is present at birth, and hearing screening is recommended throughout childhood and adolescence to identify children with late-onset HL and allow for early intervention. .
The prevalence of HL increases with age, with 40-50% of the population having HL by the age of 75. The contribution of genetic causes to adult LH cases is less clear. However, it is evident that a significant proportion of adult HL is probably caused or strongly influenced by genetic factors.
In 2014, the ACMG published a practice guideline for the clinical evaluation and etiologic diagnosis of HL. This document aimed to provide information on the frequency, causes, and clinical presentations of HL, to suggest approaches for clinical assessment, to provide methods for etiological diagnosis, and to emphasize the importance of informative and effective education. patients and genetic counselling.
The ACMG Professional Practice and Guidelines Committee reviewed the clinical practice resource document and solicited comments from the original authors. The committee believes that the original guideline still represents current clinical practice in general; However, the emergence of next-generation sequencing (NGS) technologies and associated bioinformatics tools has led to a rapid expansion of our knowledge of the genetic etiology of HL. Therefore, instead of adding an addendum to the original document, a working group was formed to update the guideline into a clinical practice resource that reflects current knowledge, particularly in the areas of genetic testing, the gene-disease relationship and the curation of LH-specific variants. .
Lead author Marilyn M. Li, MD, FACMG said, “This clinical practice resource integrated current knowledge into clinical practice and proposed a new diagnostic algorithm to provide early detection and intervention for people who are deaf. and hard of hearing to maximize language. development and quality of life. Healthcare providers should pay attention to the performance characteristics of LH tests when selecting a test for LH, including test design, genomic regions covered, technologies used, analytical sensitivity, and test limits. As knowledge of the genetic etiology of all childhood diseases, including HL, improves, genetic testing is likely to be part of more comprehensive universal newborn screening in the near future.
Key recommendations include:
- All neonates and infants with confirmed HL should undergo a comprehensive evaluation during which a patient-oriented medical and obstetrical history, as well as a three-generation pedigree and family medical history are obtained, and a physical examination focusing on dysmorphic physical findings is performed. Evaluation of children and young adults with HL should follow a similar approach. Evaluation of deaf or hard of hearing adults should be individualized based on age of onset and other characteristics of HL.
- For people whose results suggest a syndromic genetic etiology for their HL, pre-test genetic counseling should be provided and, with informed consent from the patient or caregiver, genetic testing should be ordered to confirm the diagnosis.
- For people without physical signs suggestive of a known syndrome, a multi-level diagnostic approach should be implemented.
- Referral to a multidisciplinary care center, when available, is recommended. A team approach that includes otolaryngologists, clinical geneticists, genetic counsellors, audiologists, speech and language specialists, early hearing intervention and family support specialists, and d other appropriate specialists offers the optimal opportunity to provide ongoing management and support to people who are deaf and hard of hearing. individuals as their needs change over time.
- For cases where genetic evaluation has failed to identify an underlying cause, periodic follow-up care every three years with a geneticist may be appropriate.
Early detection of HL in newborns is essential for intervention and promotion of language development. Although current physiological NBHS has significantly improved outcomes for neonates with LH, it may miss mild congenital LH, late-onset infantile LH, risk factors for aminoglycoside-induced LH and auditory neuropathy, leading to potentially preventable adverse outcomes. Currently, the considerable cost of sequencing and the complexity of interpreting the results are the main obstacles to universal genetic screening. As sequencing costs decline and knowledge of the genes and variants associated with all childhood diseases, including HL, improves, genetic testing is likely to become part of more comprehensive universal newborn screening. in a close future. This will certainly result in early audiological and etiological detection of LH with its many benefits to be realized.