Usher syndrome type 1 is a subtype of Usher syndrome (See: Usher syndrome) in which an infant is generally born deaf or severely hearing impaired. Typically, affected infants will lose most of their hearing within the first year of life.
The genes causing Usher syndrome type 1 affect the development of the inner ear. Because the inner ear plays a role in balance and coordination, individuals will often have severe balance problems. Severe balance problems may cause children to struggle sitting without support and walking on his or her own. The genes causing the condition also play a role in the development and stability of the retina (the light sensitive back part of the eye) and are associated with a condition known as Retinitis pigmentosa (See: Retinitis pigmentosa). Although vision loss may not be present at birth, it typically develops before the age of ten. The vision loss is progressive and generally starts with an inability to see at night, and then may progress to complete blindness. Diagnosis requires vision, hearing, and balance testing. In order to classify the condition as type 1, genetic testing may be necessary. Unfortunately, hearing aids are generally not effective in type 1.
Usher syndrome type 1 is inherited in an autosomal recessive manner. This means that two copies of the changed (mutated) gene are needed to produce the symptoms of Usher syndrome. In recessive conditions, both parents are unaffected carriers and each of their children will have a 25% chance of being affected. A genetic counselor can be helpful in providing a better understanding of the inheritance and recurrence risks. If your child has been diagnosed with Type 1 Usher syndrome, talk to a doctor or genetic counselor to discuss the most current treatment options.