<unk> , also known as Hallgren syndrome,<unk> her–Hallgren syndrome, retinitis pigmentosa–dysacusis syndrome or dystrophia retinae dysacusis syndrome, is a rare genetic disorder caused by a mutation in any one of at least 11 genes resulting in a combination of hearing loss and visual impairment. It is a major cause of deafblindness and is at present incurable.<unk>  is classed into three subtypes (I, II and III) according to the genes responsible and the onset of deafness. All three subtypes are caused by mutations in genes involved in the function of the inner ear and retina. These mutations are inherited in an autosomal recessive pattern. The occurrence of<unk>  varies across the world and across the different syndrome types, with rates as high as 1 in 12,500 in Germany to as low as 1 in 28,000 in Norway. Type I is most common in Ashkenazi Jewish and Acadian populations, and type III is rarely found outside Ashkenazi Jewish and Finnish populations.<unk>  is named after Scottish ophthalmologist Charles<unk> her, who examined the pathology and transmission of the syndrome in 1914.
Usher syndrome
Myhre syndrome
Sly syndrome
Irlen syndrome
McGillivray syndrome
Fabry disease
Bart syndrome
Sugarman syndrome