Question

X-linked agammaglobulinemia in infants is most likely to result in excessive infections with this type of organism. A. encapsulated bacteria B. mycobacterium C. viral D. fungal E. parasitic worms

Answer 1

Ans. 3 X linked agammaglobulinemia ( Brutons agammaglobulinemia) is characterized by failure of B cell precursors ( proB cells and B cells) to develop into mature B cells . Thus there is primary immunodeficiency involving the humoral arm of immunity i.e there is absence of antibodies resulting in increased susceptibility to certain organisms . The most common being the encapsulated pyogenic bacteria like streptococcus pyogenes , hemophillis etc. , because antibodies are the main immunity against these organisms.

Also there is increases susceptibility( increased infections ) to other organisms like fungus, viruses and some other parasites .

The main type of immunity against Mycobacterium is the cell mediated immunity which remains intact in this disease and thus there is no increased susceptibility to this orgainsm in the infant .

X linked agammaglobulinemia is caused by a mutation in a cytoplasmic tyrosine kinase enzyme called as Brutons tyrosine kinase ( Btk) .

Disease becomes apparent in an infant only after 6 months of age when the maternal immunoglobulins are depleted