Humpath.com - Human pathology

Home > D. General pathology > Genetic and developmental anomalies > Usher disease type 1

Usher disease type 1

Wednesday 12 November 2003

Usher syndrome type 1 describes the association of profound, congenital sensorineural deafness, vestibular hypofunction and childhood onset retinitis pigmentosa. It is an autosomal recessive condition and is subdivided on the basis of linkage analysis into types 1A through 1E (USH1A, USH1B, USH1C, USH1D, USH1E).

Usher syndrome type I (USH1s) is the most common cause of combined deafness and blindness in developed countries. The frequency of Usher syndrome was estimated to be 3.0/100,000 in Scandinavia and 4.4/100,000 in the United States.

Type I is distinguished from type II (276901) on the basis of severity of hearing loss and the extent of vestibular involvement. Type I patients are profoundly deaf, whereas type II patients are ’hard of hearing.’ Vestibular function is defective in type I patients, whereas type II patients have normal vestibular function.

Types

- Usher disease type 1A
- Usher disease type 1B
- Usher disease type 1C (11p15.1) (10973248)
- Usher disease type 1D : mutations in the CDH23 gene
- Usher disease type 1E

Etiology

- USH1A and USH1B is caused by mutation in myosin VIIA (MYO7A) at 11q13.5 (MIM.276903)
- USH1C (MIM.276904) on 11p15.1, the ’Acadian variety,’ is caused by mutation in harmonin (MIM.605242)
- USH1D (MIM.601067) is caused by mutation in the cadherin-23 gene (CDH23) at 10q21-q22 (MIM.605516)
- USH1E maps to 21q21 (MIM.602097) but has not been characterized at the molecular level
- USH1F (MIM.602083) is caused by mutation in the protocadherin-15 gene at 10q21-q22 (MIM.605514)
- USH1G (MIM.606943) is caused by mutation in the SANS gene (MIM.607696) at 17q24-q25

References

- Bitner-Glindzicz M, Lindley KJ, Rutland P, Blaydon D, Smith VV, Milla PJ, Hussain K, Furth-Lavi J, Cosgrove KE, Shepherd RM, Barnes PD, O’Brien RE, Farndon PA, Sowden J, Liu XZ, Scanlan MJ, Malcolm S, Dunne MJ, Aynsley-Green A, Glaser B. A recessive contiguous gene deletion causing infantile hyperinsulinism, enteropathy and deafness identifies the Usher type 1C gene. Nat Genet. 2000 Sep;26(1):56-60. PMID: 10973248