This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
A child having delayed separaion of umbilical cord with leukocytosis with Downs syndrome and recurrent infections. Diagnosis ? 
Select and explain. 
A. Leucocyte Adhesion deficiency, B. Neonatal sepsis, C. Histiocytosis-X, D. All of above
A: Leucocyte Adhesion deficiency
Answer: A: Leucocyte Adhesion deficiency 
Explanation: Leukocyte adhesion deficiency (LAD) is a rare primary immunodeficiency. The clinical picture is characterized by marked leukocytosis and localized bacterial infections that are difficult to detect until they have progressed to an extensive level secondary to lack of leukocyte recruitment at the site of infection. Thus the infections in patients with leukocyte adhesion deficiency act similarly as those observed in patients with neutropenia. See the images below. Reference: GHAI Essential pediatrics, 8th edition