Results: In this study, 16 systemic diseases were linked to premature primary tooth loss in children: Papillon–Lefèvre syndrome, mucocutaneous dyskeratosis, Coffin–Lowry syndrome, congenital adrenal hyperplasia, Langerhans cell histiocytosis, cherubism, hypophosphatasia, acatalasia, Chediak–Higashi syndrome, cyclic neutropenia, erythromelalgia, Down syndrome, Hajdu–Cheney syndrome, short bowel syndrome, leukocyte adhesion deficiency type 1 (LAD-1), and Wiedemann–Steiner syndrome (WSS). The gene discussed is LAD1; the disease is Down syndrome.