Cone-rod dystrophy is less common than rod-cone dystrophy with an incidence of approximately 1 in 80,000.
Patients present in childhood at an average age of 11 years with reduced visual acuity, symptoms of blur, reduced colour vision and central patches of missing vision. Later on, problems with night vision occurs.
The retinal changes start with thinning of the macula, the central part of the retina that controls our central vision.
As the disease progresses pigment changes in the retina develop. Recessive inheritance is most common found in 90% of cases with ABCA4 the most commonly identified gene.
Further detailed information on Alström syndrome is available from: