GJB2 and deafness: Based on the gnomAD, in contrast to the other deafness genes where the number of “observed” LOFs (loss of function variants) is equal to that of “expected” LOFs, the number of “observed” LOFs (n = 17) in GJB2 is exceptionally high compared to that of “expected” LOFs (n = 6.5) (see GJB2 on the gnomAD home page), indicating that there was a certain benefit in having GJB2 mutations in ancient times.