Khaberni - In an advanced scientific step towards understanding the causes of genetic deafness and developing its treatments, a recent international study has unveiled an exciting discovery: genetic mutations in the CPD gene lead to a rare form of congenital hearing loss.
This discovery not only identified the genetic cause but also resulted in two promising therapeutic approaches, one of which is based on a well-known drug, "Viagra".
This revelation is the fruit of collaborative research between the universities of Chicago and Miami and scientific institutions in Turkey, where scientists followed three unrelated Turkish families suffering from sensory-neural hereditary deafness, a permanent form of hearing loss usually diagnosed in early childhood. Although hearing aids and cochlear implants can improve hearing, until now there has been no medical treatment that addresses the root cause of this condition.
Through in-depth genetic analysis, researchers discovered that these families share specific mutations in the CPD gene, a gene known for its role in protein modification. More importantly, examining genetic databases revealed that other individuals carrying mutations in this gene also showed signs of early hearing loss, thus strengthening the gene's connection to hearing function.
In an attempt to understand the functioning of this gene, the team conducted experiments on mice and fruit flies and uncovered a precise mechanism whereby the CPD gene produces an enzyme responsible for generating the amino acid "arginine," which in turn aids in the production of "nitric oxide" - a crucial neurotransmitter responsible for transmitting signals across the nervous system.
When mutations occur in this gene, this pathway is disrupted, leading to oxidative stress and death of the delicate sensory hair cells in the inner ear responsible for detecting sound vibrations.
Professor Rong Grace Chai, the principal researcher in the study, explains the mechanism behind this discovery, saying, "Our research shows that the CPD gene works to maintain the appropriate level of arginine within the hair cells, which allows for the acceleration of the neural signal transmission chain through the production of nitric oxide. This mechanism explains why, despite this gene being present in many other cells across the nervous system, the hair cells in the inner ear are the most affected and vulnerable to any malfunction in the CPD gene."
The most exciting part of this study is the researchers' success in identifying two therapeutic approaches: the first relies on arginine supplements to compensate for the deficiency caused by the gene mutation, and the second uses the drug sildenafil (Viagra) to stimulate pathways affected by the nitric oxide deficiency. Both approaches have shown positive results in improving cell survival and reducing behaviors associated with hearing loss in laboratory models.
This scientific achievement not only unveils a new cause of hereditary deafness but also opens up new therapeutic possibilities. It also highlights the value of fruit fly models in studying neurological diseases, including age-related conditions, providing researchers with the ability to understand neurological diseases and identify potential therapeutic methods.
The research team is now looking to expand the scope of the study for a deeper understanding of nitric oxide signaling pathways and their role in the sensory system of the inner ear, in addition to studying the prevalence of CPD mutations in larger population groups, and verifying whether these mutations represent a risk factor for other types of sensory ailments, which may pave the way for new treatments for broader types of hearing loss.
