Hypoparathyroidism/epidemiology; Hypoparathyroidism/pathology; Abnormalities, Multiple/diagnosis; Abnormalities, Multiple/pathology; Age of Onset; Cause of Death; Child; Child, Preschool; Cohort Studies; DiGeorge Syndrome/complications; DiGeorge Syndrome/diagnosis; DiGeorge Syndrome/pathology; Fatal Outcome; Female; Growth Disorders/complications; Growth Disorders/diagnosis; Growth Disorders/pathology; Humans; Hypoparathyroidism/complications; Hypoparathyroidism/diagnosis; Hypoparathyroidism/etiology; Infant; Infant, Newborn; Intellectual Disability/complications; Intellectual Disability/diagnosis; Intellectual Disability/pathology; Longitudinal Studies; Male; Osteochondrodysplasias/complications; Osteochondrodysplasias/diagnosis; Osteochondrodysplasias/pathology; Retrospective Studies; Seizures/complications; Seizures/diagnosis; Seizures/pathology