Developmental delay is a common problem in population (2-3%). It is quite often an indication of delayed or abnormal brain development. Majority of people with developmental delay grow up to have intellectual disability. Genetic mutations cause majority of cases of intellectual disability. We plan to study genetic mutations that are common in general population and any one of these on its own does not cause intellectual disability. When someone caries many of these mutations together then they may have intellectual disability. The method we are proposing to use has been successfully used to study many different diseases including diabetes and depression. Better understanding of the genetic mutations leading to intellectual disability will lead to strategies to prevent this problem as well as better treatment options. We will use UKBIOBANK data as controls. We may also use the data to validate our findings.