Screening Protocol for Genetic Diseases of Lymphocyte Homeostasis and Programmed Cell Death

* INCLUSION CRITERIA: Patients known to have or suspected of having an inherited immune cell homeostasis, programmed cell death susceptibility syndrome, lymphocyte developmental block, or defective immune cell effector functions will be eligible for enrollment. We will enroll patients with suspected disease if the investigator agrees that there is a high index of suspicion. Blood relatives of enrolled patients will be eligible for enrollment. There will be no limit as to age, sex, race, or disability. EXCLUSION CRITERIA: Severely debilitated health status or poor venous access may preclude obtaining adequate specimens for analysis. The minimum weight for infants on this protocol is 3 kg because of the limits of maximal acceptable blood draw volumes and minimum requirement for core laboratory tests would exceed the acceptable volume. Co-enrollment guidelines: Participants may be co-enrolled in other studies including NIH protocols 05-I-0213, 93-I-0063 and 17-I-0122. Participants should inform the investigator of participation in other research studies.