USH2A and deafness: Among the families, 85.3% showed causative variants in autosomal genes (most frequently ABCA4, USH2A, PRPH2, and BEST1), 13.7% in X-linked genes (most commonly RPGR, RS1, and CHM), and 1.0% in mitochondrial genes (including those implicated in Leber hereditary optic neuropathy and maternally inherited diabetes and deafness).