What is the definition of Usher Syndrome Type 2A?
Usher syndrome type 2A is a genetic condition characterized by hearing loss from birth and progressive vision loss that begins in adolescence or adulthood. Vision loss is due to retinitis pigmentosa. Night vision loss begins first, followed by blind spots that develop in the side (peripheral) vision. Over time, these blind spots enlarge and merge to produce tunnel vision. In some cases, vision is further impaired by clouding of the front surface of the eye (cataracts). Hearing loss ranges from mild to severe and mainly affects high tones. The degree of hearing loss varies within and among families with this condition. Unlike other forms of Usher syndrome, people with type 2A do not have difficulties with balance caused by inner ear problems. Usher syndrome type 2A is caused by mutations the USH2A gene and is inherited in an autosomal recessive manner.
What are the alternative names for Usher Syndrome Type 2A?
Is Usher Syndrome Type 2A an inherited disorder?
Usher syndrome is inherited in an autosomal recessive manner. This means that a person must have a disease-causing change (mutation) in both copies of the gene associated with the syndrome in each cell to have Usher syndrome. One mutated copy is typically inherited from each parent, who are each referred to as a carrier. Carriers of an autosomal recessive condition usually do not have any signs or symptoms.
When two carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) chance to have the condition, a 50% (1 in 2) chance to be an unaffected carrier like each parent, and a 25% chance to not be a carrier AND not be affected.