How audiologists play a role in genetic counseling and what Connexin 26 is

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Hearing Loss and Connexin 26
Hereditary hearing loss affects approximately a single baby out of every 2000 newborns (Mani, Ram Shankar et al. 2016). Audiologists are professional medical practitioners trained to critically and precisely evaluate and diagnose hearing loss patients and are uniquely involved in carrying out research into the circumstances that contribute to a patient’s hearing loss either from hereditary or non-hereditary, syndromic or non-syndromic causes. This role is vital in genetic etiologies as the tests and diagnosis results may be used in offering regarding recurrent risks as well as other potential implications. Audiologists are therefore expected to identify cases of genetics referral, as well as counseling patients and their caregivers on the benefits and limitations that are related to genetic testing. Audiologists are also involved in the interpretation of genetic test results for the respective patients. On the other hand, connexin 26 has stood out as the most common cause of hearing the loss in some parts of the world that include the US, Japan and Europe. This essay, therefore, is focused on analyzing the contributions of audiologists in hereditary diseases as it regards genetic counseling, as well as the role of Connexin in causing hearing loss considering its non-syndromic mutation nature.
Audiologists role in attending to hearing loss patients is not only limited to diagnoses and treatment, but extends to offering guidance and counseling regarding the patients’ health conditions and recommendations on the best recovery practices.

For instance, audiologists, at a minimum, are expected to possess adequate knowledge so as to identify cases when a genetic referral is given. Also, it is the audiologist’s responsibility to come up with a precise approach on how to disclose such an issue to patients. Audiologists are therefore expected to advice patients on whether their hearing loss cases require genetic evaluation or not. Before treatment, the audiologist is expected to enquire from the patient or the person responsible if an etiology has been established. If so, the audiologist should also confirm if the etiology was successfully established on the patient. The audiologist is also responsible for enquiring cases of family hearing loss to establish if the problem is hereditary or not (Kochhar, Hildebrand & Smith, 395).
Audiologists are also responsible for talking to parents and the hearing loss patient’s caregiver about genetic testing. This involves advising the latter on the benefits of genetic testing. However, some parents might be eager to demand a genetic diagnosis, while others might listen to the pre-diagnosis advice. It is the responsibility of an audiologist to narrate the implications of genetic testing to patients and their parents so as to make them aware of the importance of genetic testing before treatment. For instance, the audiologist a sample piece of advice an audiologist may give to parents of a hearing loss patient includes the essence of genetic testing in combating future recurrence of the same disease, as well as the sensitive prognosis information this testing is bound to offer (Mercer, 458). Positive genetic test results might possess various psychological impacts on the patient himself and the parents thus it is the responsibility of audiologists to offer encouraging advice to the parents, and the impacts this may have once the information is revealed to the extended family. Additionally, audiologists should clarify to patients that negative genetic testing results do not confirm that the disease is non-genetic as the condition might have been caused by several other non-syndromic causes (Kochhar, Hildebrand & Smith, 401).
Connexin 26 (GJB2)
This is the most prevalent non-syndromic cause of hearing the loss in most parts of the world. Genetic conditions are however more heterogeneous in causing hearing loss and several genes are therefore linked with non-syndromic hearing loss. Connexin 26 causes hearing loss via a process that involves encoding a gap junction protein that is bound to develop intercellular channels. These channels are formed through a side to side positioning of connexin subunits. This positioning occurs between two adjacent cells. This process extends to the inner ear whereby the intercellular channels can be observed from such parts of the inner ear as the spiral limbus. Also, the channels are expressed in stria vascularis, spiral ligament, as well as the supporting cells. Transportation of fluids and other tiny molecules is hence permitted. A recent proposal suggests that potassium ions that are required to cause action potentials within the inner ear’s hair cells and inositol are transmitted via specific gap junction channels that originate from stria vascularis and supporting cells. A three dimension structure is created and manifests a prominent electron density within certain existing pores of each hemichannel.
Connexin 26 mutations are attributed to approximately over a fifth of all genetic hearing loss cases in newborns. However, in some ethnic populations, mutated Connexin 26 genes account for over 80% of the total non-syndromic recessive deafness (Mani, Ram Shankar et al. 2016). Connexin 26 mutations are inheritable and therefore are transferrable from parent to child via genes. This however happens in a recessive manner. For full inheritance of Connexin 26, a child must inherit a single copy from each parent. The copies are of the non-functioning gene. However, carriers possessing a single copy of the gene do not show any hearing loss symptoms. These carriers possess a single normal as well as a single mutated gene, and therefore stand a half chance of transmitting the defective gene to the newborns. However, the children, if they inherited the single copy of genes, would also change to carriers only. Connexin 26 is fundamental in hearing as it is responsible for the production of several proteins. The proteins are referred to as gap-junction proteins and are responsible for intercellular communication. Connexin 26 insufficiency in the body results in profound sensorineural hearing loss (Mani, Ram Shankar et al. 2016).
Works Cited
Kochhar, Amit, Michael S. Hildebrand, and Richard JH Smith. “Clinical aspects of hereditary hearing loss.” Genetics in Medicine 9.7 (2007): 393-408.
Mani, Ram Shankar et al. “Functional Consequences Of Novel Connexin 26 Mutations Associated With Hereditary Hearing Loss”. NCBI, 2016, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2986212/.
Mercer, Danielle. “Guidelines For Audiologists On The Benefits And Limitations Of Genetic Testing”. American Journal Of Audiology, vol 24, no. 4, 2015, p. 451-461. American Speech Language Hearing Association, doi:10.1044/2015_aja-15-0010.