Usher syndrome in the city of Birmingham---prevalence and clinical classification

Abstract

Aims-To estimate the prevalence of Usher syndrome in the city of Birmingham, and to establish a database of patients who have been classified into diVerent clinical subtypes essential for future gene mutation analysis. Methods-Symptomatic cases of Usher syndrome (US) resident in the city of Birmingham in June 1994 were ascertained through multiple sources. Ophthalmic and audiological reassessment together with examination of medical records and patient questionnaires allowed classification of three subtypes, US 1, US 2, and US 3. In addition, family pedigrees were examined and blood was taken from index patients for DNA extraction. Results-In the population aged over 15 years the prevalence was 6.2 per 100 000 population for all US subtypes. The prevalence for US 1 and US 2 was 5.3 per 100 000 population. This is greater than previously reported. In the age group 30-49 years the prevalence approached 1 in 10 000. Clinical classification found 33% US 1, 47% US 2, and 20% US 3. Conclusion-This higher prevalence rate and greater frequency of US 2 and US 3 may reflect a more complete ascertainment. (Br J Ophthalmol 1997;81:46-53) The Usher syndromes (US) are a heterogeneous group of autosomal recessive disorders characterised by congenital hearing loss associated with a progressive pigmentary retinopathy. This association was first described by von Graefe, 1 but it was Charles Usher who first emphasised its familial occurrence.

Frecuencia de mutaciones en el gen de la usherina (USH2A) en 26 individuos colombianos con síndrome de Usher, tipo II

“…Abajo: secuencia sin la mutación. En el caso del presente estudio, la proporción de individuos con síndrome de Usher de fenotipo 2 fue inferior, lo que podría explicarse porque la tamización se llevó a cabo principalmente en escuelas para sordos y los individuos con el síndrome de tipo 2 usualmente asisten a escuelas regulares; en contraste, en los países europeos la selección de pacientes se hace en clínicas oftalmológicas (10,12,20), lo que facilita la detección de individuos con retinitis pigmentaria que presenten, además, una hipoacusia leve o moderada de la que no se hayan percatado.…”

“…Hasta el momento, no se han reportado mutaciones de este tipo en el gen USH2A, por lo que el cambio identificado en este estudio podría ser la primera mutación reportada y representa una frecuencia de 4 % en la población analizada. Algunos estudios que hacen identificación de las mutaciones del gen, excluyen la región promotora y sólo analizan la región codificante (10,17,26), por lo que es posible que los cambios en esta región no estén siendo detectados en otras poblaciones.…”

“…Entre los tipos clínicos identificados hasta el momento, el de tipo II es la forma más común de síndrome de Usher, ya que se presenta en casi la mitad de los casos reportados (10)(11)(12). Algunos estudios han demostrado que de 74 % a 83 % de los casos con fenotipo 2, corresponden al subtipo 2A (13)(14)(15)(16).…”

Mutation analysis of the MYO7A and CDH23 genes in Japanese patients with Usher syndrome type 1

“…1 It is the most common cause of combined deafness and blindness in industrialized countries, with a general prevalence of 3.5-6.2 per 100 000 live births. [2][3][4][5][6][7] The syndrome is clinically and genetically heterogeneous and can be classified into three clinical subtypes on the basis of the severity and progression of HL and the presence or absence of vestibular dysfunction. [8][9][10] USH type 1 (USH1) is characterized by congenital severe-toprofound HL and vestibular dysfunction; it is the second common type after USH type 2 and accounts for 25-44% of the USH cases.…”

Prevalence of cystic macular lesions in patients with Usher II syndrome

“…Usher syndrome type II is the most common form, [1][2][3][4] with onset of visual impairment in the second decade, congenital sensorineural hearing loss, most severe at high frequencies, and absence of vestibular dysfunction. 5,6 Previous studies have categorized the macular findings in Usher patients as either normal, showing cystoid macular oedema (CME), macular holes, or an atrophic-appearing lesion.…”