by Neil Bauman, Ph.D.
More and more children are being found to have a hearing loss due to what is called Large (or Enlarged) Vestibular Aqueduct Syndrome (abbreviated to either LVAS or EVAS).
LVAS is passed on from generation to generation by recessive genes. That much researchers know. How many genes are involved in LVAS? No one knows.
So far researchers have now traced the gene thought to be responsible for LVAS to a location on chromosome 7q31 in a region that overlaps the area containing the gene responsible for Pendred syndrome (PDS).
As I wrote back in 2002, “This suggests that different mutations in the PDS gene can cause a variety of related conditions ranging from nonsyndromic recessive hearing loss (NSRHL) with enlarged vestibular aqueducts (basically LVAS) to the severe Mondini deformity and Pendred Syndrome. Some people with Pendred Syndrome have fluctuating hearing loss similar to that observed in people with LVAS.
Another theory is that a separate gene responsible for LVAS may exist close to the Pendred gene, and that mutations in both are required for full Pendred syndrome, whereas a mutation in only one of these genes may result in hearing loss associated with a variety of cochlear abnormalities.” (1)
The truth is, many more genes may be involved in LVAS than the one or two related to Pendred syndrome that have been discovered so far.
Did you know that of the approximately 20,000 genes in the human body, “more than 4,500 genes participate in the development and maintenance of the human inner ear, making it the most genetically complex organ in the human body.”
Researchers also know that hundreds of genes are involved in hereditary hearing loss, leading to syndromes such as Waardenberg, Usher and Pendred.” (2)
From the above, it is obvious that researchers still have a long ways to go in order to identify all the genes that go into making up LVAS. I say this because hearing loss (and balance problems) do not seem to correlate with the size of the vestibular aqueducts or anything else so far. In fact, some people don’t have an hearing loss at all in an ear with LVAS. Thus some critical information is still missing.
Until then, and with so many unknown variables related to LVAS, it will continue to be very difficult to effectively diagnose and manage LVAS.
(1) Large Vestibular Aqueduct Syndrome (LVAS)by Neil Bauman, 2002.
(2) In “Advance for Audiologists” (July 22, 2008) by Jess Dancer, Ed. D.