Genetic Testing and Phenotypic Characterization of Severely Obese Pediatric and Adult Volunteers

Individuals who meet any of the following inclusion criteria may be eligible: 1. Participant aged 2 or older. 2. Study participant and/or parent or guardian is able to communicate well with the investigator, to understand and comply with the requirements of the study, and be able to understand and sign the written informed consent/assent. 3. ≥40kg/m2 (age 18 and older) or 1.4x 95th percentile of BMI for age (ages 2-17) - with evidence of hunger or hyperphagia by screening surveys, indicated by a patient or observer score at or greater than midpoint of scale. o Individuals with clinical evidence of RGDO (per appendix 4) but do not meet the BMI criteria may be included if the investigators estimation and proband demonstrates a BMI Z-score difference of \>1 between proband and any other sibling; and/or the proband demonstrates a BMI difference \>10 kg/m2 between proband and parents. 4. ≥50 kg/m2 (age 18 and older) or 1.5x 95th percentile of BMI for age (ages 2-17). Cohorts included under this criteria include ≥50-60 kg/m2 (age 18 and older) or 1.5x 95th percentile of BMI for age (ages 2-17) and ≥60 kg/m2 (age 18 and older) or 1.6x 95th percentile of BMI for age (ages 2-17). 5. ≥ 40 kg/m2 (pre-operative) or 1.4x 95th percentile of BMI for age (ages 12-17) with history of bariatric surgery or planned surgery within 3 months (prior to or following screening). Individuals who meet any of the following exclusion criteria will not be eligible: 1. Prior craniopharyngioma or other hypothalamic brain region surgery or surgeries/procedures for brain tumor, i.e., ventriculoperitoneal shunt and radiation therapy 2. Diagnosis of Prader-Willi syndrome