Inclusion Criteria:  Healthy children and adolescents  Exclusion Criteria:  In case of acute disease, cancer, cancer therapy, or chronic disease (History of malignant disease, chemotherapy or radiation, cystic fibrosis, juvenile rheumatoid arthritis, systemic lupus erythematosus, sickle cell disease, thalassemia, chronic renal disease or known numerical chromosome aberration) Non-Caucasian