Usher syndrome type 3 is a condition that leads to a gradual loss of hearing and vision.
The speed at which these losses happen can be different for each person, even within the same family. Some may experience profound hearing and/or vision loss, while others may have milder effects. People with Usher syndrome type 3 are born with normal hearing, but they commonly start losing their hearing in their teenage years. By the time they reach middle age, many are completely deaf. This type of Usher syndrome also causes an eye condition called retinitis pigmentosa. It often begins during puberty, causing night blindness that develops into blind spots in the late teens or early adulthood. Peripheral vision is usually the first to decline, and by mid-life, some individuals may be legally blind.
Unlike other forms of Usher syndrome, type 3 typically doesn’t cause major balance problems, though some issues may arise later in life. The condition doesn’t affect intelligence and doesn’t lead to other health problems. While there’s no cure for Usher syndrome, there are ways to improve the impact it has on vision and hearing. People with Usher syndrome type 3 usually learn to speak normally before their hearing declines. They have various options to explore, such as cochlear implants, hearing aids, or using sign language.
Usher syndrome type 3 is caused by pathogenic (disease-causing) variants in the CLRN1 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 120 chance to be a carrier.
Other names for this condition are deafness-retinitis pigmentosa syndrome, Graefe-Usher syndrome, and Hallgren syndrome.