Clinical Guidance

No clinically relevant genotype-phenotype correlations have been identified in individuals with biallelic SLC26A4 pathogenic variants.

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"

Diagnostic Criteria

No consensus clinical diagnostic criteria for SLC26A4-related sensorineural hearing loss (SLC26A4-SNHL) have been published.

Suggestive Findings

SLC26A4-SNHL should be considered in probands with the following clinical findings of sensorineural hearing loss, inner ear malformations, vestibular dysfunction, and thyroid abnormalities and family history .

Clinical findings

• Sensorineural hearing loss (SNHL)

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"

Differential Diagnosis

Congenital (or prelingual) genetic hearing loss affects approximately one in 1,000 newborns; 30% of these infants have additional anomalies, making the diagnosis of a syndromic form of hearing loss possible (see Genetic Hearing Loss Overview). Temporal bone malformations • Although enlarged vestibular aqueduct (EVA) with or without cochlear hypoplasia are seen in virtually all individuals with SLC26A4-related sensorineural hearing loss (SLC26A4-SNHL), neither EVA nor cochlear hypoplasia is specific to SLC26A4-SNHL. Other causes of these types of temporal bone malformations include acquired conditions such as congenital cytomegalovirus (cCMV) infection and genetic disorders . • SLC26A4 molecular genetic testing is not indicated for individuals with temporal bone anomalies that do not match the typical SLC26A4-SNHL-associated findings. Anomalies not associated with SLC26A4-SNHL include cochlear aplasia, Michel aplasia, common cavity malformation, and isolated semicircular canal dysplasia. Table 2. Genetic Disorders with Temporal Bone Malformations in the Differential Diagnosis of SLC26A4-Related Sensorineural Hearing Loss

Management Guidelines

No clinical practice guidelines for SLC26A4-related sensorineural hearing loss (SLC26A4-SNHL) have been published. In the absence of published guidelines, the following recommendations are based on the authors' personal experience managing individuals with this disorder.

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with SLC26A4-SNHL, the evaluations summarized in this section (if not performed as part of the evaluation that led to the diagnosis) are recommended.

• Assessment of auditory acuity (auditory brain stem response testing, pure tone audiometry)

• Assessment of vestibular function during early childhood (should be considered)

• Thyroid ultrasonography and thyroid function tests (T3 [triiodothyronine], T4 [thyroxine], and TSH [thyroid-stimulating hormone]) during early childhood with endocrinologist consultation as needed

• Consultation with a clinical geneticist, certified genetic counselor, certified genetic nurse, or genetics advanced practice provider (nurse practitioner or physician assistant) to inform affected individuals and their families about the nature, mode of inheritance, and implications of SLC26A4-SNHL to facilitate medical and personal decision making

• Assessment of need for family support and resources including community or online and social work involvement for parental support

See also Genetic Hearing Loss Overview.

Treatment of Manifestations

There is no cure for SLC26A4-SNHL. For general informa...

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"

Clinical Guidance

See Genetic Hearing Loss Overview, Agents/Circumstances to Avoid. There are anecdotal reports that increased intracranial pressure in individuals with enlarged vestibular aqueduct (EVA) can occasionally trigger a decline in hearing, leading some providers to recommend avoiding activities like weightlifting and contact sports . However, evidence is insufficient to support the claim that avoiding these activities will decrease the risk of overall hearing loss progression . While health care providers should alert families to the possible association between EVA and hearing loss following head injuries, families should be encouraged to make their own decisions on participation in contact sports, taking into account that head trauma may not significantly affect the overall risk of hearing loss progression .

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"

Therapies Under Investigation

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"

Surveillance Guidelines

To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the following evaluations are recommended.

Hearing loss

• The primary focus should be routinely scheduled audiometric follow up that includes assessment of suitability for CI to avoid unnecessary and counterproductive delay if/when the hearing loss progresses and hearing aids are no longer adequate .

• Repeat audiometric testing every three to six months until age three years and annually thereafter.

Thyroid function

• Baseline ultrasonography should be performed to assess thyroid size after age ten years and repeated every five to ten years based on findings on palpation of thyroid size. (The odds of developing a goiter are 1.1 for each one-year increase in age. Thus, after age 20 years, the increase in odds of developing goiter is 6.7-fold ).

• While tests of thyroid function are usually normal in individuals with SLC26A4-SNHL irrespective of thyroid size, this testing is important in the evaluation and management of signs and symptoms of hypo- and hyperthyroidism and should be considered when the medical history and/or physical examination suggest thyroid dysfunction .

Source: GeneReviews — "SLC26A4-Related Sensorineural Hearing Loss"