PCDH15 and blindness (disorder): Worldwide theprevalence is noted to be between 4 and 17 in 100,000.[28,29,30] The prevalence of USH in theUnited States is 4.4/100,000.[31] It is inherited in an autosomal recessive fashion and is themost common cause for hereditary deafness and blindness in children, constituting5% of congenital deafness and 18% of all retinitis pigmentosa patients.[28,32] The major genes affected include MYO7A(USH1B), USH1C, CDH23, PCDH15(USH1F), USH2A, and USH3A.