A patient with Xlinked immunoglobulin XLA presents with very

A patient with X-linked immunoglobulin (XLA) presents with very low IgG and IgM and no IgA. If BTK causes arrestment of all B-cell development before they can produce antibodies, how are any IgM / IgG being produced, and why is IgA not produced at all?

X-linked immunoglobulin (XLA) or Briton\'s agammaglobulinemia is an inherited disease is due to the mutation in B lymphocytes. The mutation impairs antibody production.