To evaluate genetic disease among children referred to a community paediatric clinic.Retrospective cohort study.Community paediatric clinic, Tower Hamlets, London.All patients seen for first time in the Child Development Team (CDT) clinic between 1999 and 2013.Clinical notes were reviewed. Genetic test results were obtained. Exploratory Excel analysis was performed. Patients without an identified genetic disorder were labelled 'more likely genetic cause' if they had at least two out of three risk factors: developmental delay, congenital abnormality or parental consanguinity, and 'unlikely genetic cause' if they had one or no risk factors, or an obvious alternative cause.Prevalence of genetic diagnoses and parental consanguinity, undertaking of genetic tests, predicted likelihood of a genetic cause among unsolved patients.749 patients were included. 404 (53.9%) had undergone genetic testing and 158 of those tested (39.1%) had a confirmed genetic diagnosis. Parental relatedness was documented in 461 patients, of which 128 (27.8%) had first-cousin parents. The number of patients undergoing genetic testing increased over time. Aneuploidies and syndromic/Mendelian disorders were most common. Of the 591 patients without a genetic diagnosis, 29.9% were classified 'more likely genetic cause'. Patients with consanguineous parents were significantly more likely to have a diagnosed genetic disorder than those with non-consanguineous parents (43/128 vs 72/333), particularly an autosomal recessive condition (27/43 vs 6/72).Genetic disease was common and genetic testing is important in evaluating children in this clinic. Consanguinity increases the likelihood of autosomal recessive disease.