Presentation: Child with non-syndromic hearing loss

You see a three-year-old child with speech delay in clinic, accompanied by the parents. The child is otherwise fit and healthy, with normal gestation, birth and medical history. You perform a thorough physical and neurological examination, the findings of which are normal. You request an audiological assessment, and the results from the audiogram reveal bilateral sensorineural deafness.

Non-syndromic hearing loss is a partial or total loss of hearing not associated with other signs or symptoms (in contrast to syndromic hearing loss, in which other parts of the body are affected too). It can be unilateral or bilateral, pre-lingual or post-lingual and can vary from mild to profound. It can be sensorineural (that is, structures of the inner ear are affected) or mixed (a combination of sensorineural and conductive hearing loss).

Genomic testing in cases of non-syndromic hearing loss should be considered when there is a family history of bilateral or unilateral hearing loss consistent with a monogenic cause (often suggested by audiograms).

• Consult the National Genomic Test Directory. here you can access the rare and inherited disease eligibility criteria, which provides information about individual tests and their associated eligibility criteria. You can also access a spreadsheet containing details of all available tests.
  • For those working within NHS Wales, please consult the All Wales Medical Genomics Service website for information on how to arrange testing.
• To find out which genes are included on different gene panels, see the NHS Genomic Medicine Service (GMS) Signed Off Panels Resource.
• Decide which of the panels best suits the needs of your patient or family. For non-syndromic hearing loss, there are a number of available panels, including:
  • R67.1 Hearing loss (whole exome sequencing or large panel); and
  • R67.2 Hearing loss (multiplex ligation-dependent probe amplification (MLPA) detecting copy number variations in DNA).
• These tests do not include whole genome sequencing (WGS), therefore:
  • you can use your local Genomic Laboratory Hub test order and consent (record of discussion) forms; and
  • parental samples may be needed for interpretation of the child’s (proband’s) result. Parental samples can be taken alongside that of the child, and their DNA stored, or can be requested at a later date if needed.
• These tests are DNA-based, and an EDTA sample (purple-topped tube) is required.
• Information about patient eligibility and test indications was correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.

For clinicians

• Genomics England: NHS Genomic Medicine Service (GMS) Signed Off Panels Resource
• Medline Plus: Non-syndromic hearing loss
• NHS England: National Genomic Test Directory

References:

• del Castillo I, Morín M, Domínguez-Ruiz M and others. ‘Genetic etiology of non-syndromic hearing loss in Europe’. Human Genetics 2022: volume 141, pages 683–696. DOI: 1007/s00439-021-02425-6
• Wang J, Xiang J, Chen L and others. ‘Molecular diagnosis of non-syndromic hearing loss patients using a stepwise approach’. Scientific Reports 2021: volume 11, article 4,036. DOI: 10.1038/s41598-021-83493-6

For patients

• Centers for Disease Control and Prevention: A parent’s guide to genetics and hearing loss (PDF, 28 pages)
• National Deaf Children’s Society: Does my child have a hearing loss?