PAX6 and respiratory distress syndrome in premature infants: While traditional single-gene sequencing may be sufficient for diagnosing IRDs with mostly only one disease-associated gene identified, such as congenital anirdia (PAX6 gene), systematic testing of single genes may be inefficient for diagnosing more complex IRDs that have a high degree of genetic heterogeneity, such as retinitis pigmentosa (> 100 identified causative genes) [2, 7, 8, 12, 19, 29].