“…In the mitochondrial tRNA Ser(UCN) gene, five nonsyndromic deafness-associated mutations, A7445G [42][43][44], 7472insC [45][46][47], T7510C [48,84], T7511C [49][50][51][52][53], and G7444A [55][56][57], have been found in families from various ethnic backgrounds. These mutations often occur in homoplasmy or in high levels of heteroplasmy, indicating a high threshold for pathogenicity.…”