The familial incidence of symptoms of Scotopic Sensitivity/Irlen Syndrome:Comparison of referred and mass-screened groups

The familial incidence of Scotopic Sensitivity/Irlen Syndrome was in vestig ated in two samples. One sample involved parents and siblings of 126 childr en identified with symptoms who had been referred for screening. The other sample involved parents and siblings of 33 children who had been identified with symptoms through mass screening of all children in Grades 3 to 6 at t wo local schools. Two different samples were taken to investigate the possi bility of parental referral bias. Familial incidence may be inflated in a r eferred sample because some parents may be aware of their own symptoms and actively seek assistance. For the sample of children referred for screening , there was an 81% chance of either one or both parents showing similar sym ptoms and a 76% chance of siblings being similarly affected. For the sample of children identified through school screening, there was an 85% chance o f either one or both parents showing similar symptoms and a 54% chance of s iblings being similarly affected. The data confirm previous estimates of in cidence and suggest that Scotopic Sensitivity/Irlen Syndrome may be a genet ically-based deficit in visual processing.