CORE A: RECRUITMENT AND PHENOTYPING CORE ABSTRACT: Although congenital diaphragmatic hernia (CDH) is a common birth defect, it is still relatively rare and requires infrastructure for recruiting, clinically characterizing, and obtaining biospecimens on patients, and is the foundation for the success of this Program Project. By merging two well-established CDH research programs (Massachusetts General Hospital/Boston Children’s Hospital and Columbia/DHREAMS) we have established one of the largest and most carefully characterized CDH cohorts in the world. Collectively, these two studies have enrolled 1500 patients with CDH and 2683 unaffected family members, and ongoing recruitment is expected to enroll 900 additional patients over the course of this 5 year grant. This Core supports the recruitment and consent of participants, collection of extensive phenotypic data including retrospective medical record review and longitudinal clinical follow-up, collection and processing of biospecimens, and management of data and IRB protocols. The specimens collected will be used extensively for all genomic studies proposed in Project I. Furthermore, the detailed phenotyping of human subjects will be instrumental in the interpretation of data derived from mouse models in Projects II and III, and patient-specific cell lines will be used for functional assays in Project III.