Among those IRDs are (1) USH1D, a severe form of autosomal recessive blindness-deafness which accounts for 19%–35% of cases of Usher syndrome type 129, 30, 31 and which is caused by mutations in CDH23 (CDS, 10.1 kb), which encodes for the Cadherin-related family member 2332, 33 and (2) ALMS, an autosomal recessive condition, with a prevalence of less than one per million34, and characterized by a combination of features including obesity, insulin resistance, and retinal dystrophy. Here, CDH23 is linked to Alstrom syndrome.