Usher syndrome in four Norwegian counties

Area of Science:

• Ophthalmology
• Genetics
• Audiology

Background:

• Usher syndrome is a leading genetic cause of combined vision and hearing impairment.
• This study investigates the prevalence and characteristics of Usher syndrome within a cohort of patients diagnosed with tapeto-retinal degeneration.

Observation:

• Eighteen out of 89 probands (20%) with tapeto-retinal degeneration received an Usher syndrome diagnosis.
• An additional 10 Usher syndrome cases were identified among relatives.
• Usher syndrome types I, II, and III were diagnosed in 14, 10, and 4 cases, respectively.

Findings:

• Autosomal recessive inheritance was observed in 12 families; six probands were solitary cases.
• High intrafamilial correlation in hearing function suggests genetic heterogeneity.
• Vestibular function varied, with abolished responses in some Usher syndrome type I patients and normal responses in some type II and III patients.
• Visual prognosis was not strongly correlated with type or age of hemeralopia onset, with function declining after age 50.

Implications:

• Understanding the genetic heterogeneity of Usher syndrome is crucial for accurate diagnosis and genetic counseling.
• This research highlights the importance of comprehensive audiological and ophthalmological evaluations in patients with tapeto-retinal degeneration.
• The findings contribute to the knowledge of Usher syndrome's clinical spectrum and natural history.