 In this study, subjects will be recruited as two populations: control and diseased. In the control population, plasma samples of healthy newborns will be acquired at the time of blood collection for state-mandated newborn screening from Parkland. We will also collect blood from healthy children from the clinics at Childrens Medical Center CMC, again piggybacking this research sample with venipuncture for clinically indicated blood collection. All plasma samples will be subjected to metabolomics to determine the healthy ranges for a large number of metabolites. This comprehensive profile of metabolites in children will be used as normative ranges to identify outlying metabolites in diseased subjects. Additionally, if suspected metabolic outliers are detected from this normal population, DNA samples extracted from the leftover packed cells or blood samples will be subjected to genomic sequencing to profile the associated gene mutations. The diseased population will be recruited from the clinics of the Pediatric Genetics and Metabolism Division in the Department of PediatricsCMC. Blood and DNA samples will be collected from patients for metabolomic analysis and next-generation sequencing respectively to define the metabolic abnormalities and associated gene mutations. Skin fibroblasts from patients will also be collected and used for biological validation of the metabolic effects of novel mutations, in particular by complementing diseased fibroblasts with wild-type alleles of genes mutated in the patient. If any rare Mendelian disorder is considered in a subject, blood from hisher family members will be acquired and subjected to metabolomic and genomic analyses to facilitate identification of the diseased-associated genes. 