According to my new ENT, there's a problem with my connexins. These proteins, pictured above, assemble in a pretty flower shape on cell membranes, interacting with connexins on neighboring cells to form gap junctions. Gap junctions turn out to be important to neurochemical signaling. So, specific types of mutations in the genes encoding connexins can lead to deafness and/or hearing loss.
I elected not to have any genetic testing done at this point, because it wouldn't change my treatment, but the doctor said that connexin mutations are the most frequent causes of slowly progressive sensorineural hearing loss -- and that these mutations, autosomal recessive alleles, occur at a higher prevalence among Ashkenazic Jews (who, it turns out, are also susceptible to fat metabolism disorders and GI disorders, probably among other things I haven't learned about yet. All those population bottle-necks, I guess?). So it's likely that this is what's wrong with me.
I guess it's nice to know that. It gives it some closure, and gives me a good idea what might be in store in the future. It's also a little weird, though, being someone with a "rare genetic condition", whom I should be seeing on an evening news story rather than, well, the person who is looking out through my eyes. It took me awhile to get used to being "the girl who wears hearing aids"; now I guess I'm also "the girl with the rare genetic disease." I got used to the hearing aids, though, so I'm sure I'll get used to this -- it'll just take some time.