RecruitingGene Discovery Core, The Manton CenterThe Gene Discovery Core at The Manton Center for Orphan Disease Research based at Boston Children's Hospital studies families with rare, poorly understood or undiagnosed, but suspected genetic conditions. The primary goal of the research is to better understand the genes and proteins (gene products) involved in rare diseases. The researchers hope that our studies will allow for improved diagnosis and treatment of individuals with rare disease in the future. Individuals with any rare/undiagnosed condition are eligible to enroll. Enrollment includes: * Providing DNA and tissue samples (when available) * Access to participants' medical records * Access to genomic data (when available) Samples are used for genetic analysis (primarily exome and genome sequencing or reanalysis) to identify the genetic cause for the individual's illness. Individual research results are returned to families through their health care provider after confirmation in a clinical lab. If a cause is identified, that can be reported back to the family through their health care provider and the study's genetic counselor. When possible, the investigators also collect samples from parents and full-siblings as well as any other affected family members.