<prompt> Burtons agammaglobulinemia is due to?B-cell defectIgA deficiencyIg M deficiencyIg G deficiency  <response>: X-Linked agammaglobulinemia of burtono There is defective humoral immunity with normal cell mediated immunity. It is characterized by the failure of B cell precursors Pro-B cells and pre B cells to mature into B cells. There is mutation in cytoplasmic tyrosine kinase called B - cell tyrosine kinase BtK.o The disease usually does not become apparent until about age 6 months, when maternal immunoglobulins are depleted.o B cells are absent or markedly decreased in the circulation, and the serum levels of all classes of immunoglobulin. There is depletions of B cell area oflymphnode Cortical follicles and medullary cord and spleen perifollicular region, germinal centre and mantle layer. Tonsil and adenoids are atrophico T-cell collection areas are normal i.e. i Paracorticalarea in lymph nodes, and ii Periarterial lymphoid region malpighian corpuscle in white pulp of spleen.o The disease is seen almost entirely in males. There is recurrent bacterial infections of respiratory tract by H. influenzae, str. pneumoniae or staph, aureus. There is increased susceptibity to infection with enterovirus echo, coxsackievirus, poliovirus, giardia lamblia, and arthritis by mycoplasmao As there is agammaglobulinemia, Opsonization is defective Immunoglobulins are the major opsonins in body. 