(mutations) known to be causal of rare disease. For most common conditions studied to date, family history, clinical characteristics and environmental factors account for a much larger proportion of measurable risk. As more is learned about genetic risk factors for common conditions the situation may change, but for now genotyping has little role in providing risk prediction for common conditions.29 However, GWAS have already proved extremely helpful in better understanding the underlying biology of literally scores of conditions, including many that affect children.27,30,31
