Undifferentiated connective tissue disease associated with deficiency of IgG2 and IgG4

The undifferentiated connective tissue disease is a condition of unknown etiology that shares clinical, pathological and laboratory characteristics with several collagenases, without meeting the criteria of the American College of Rheumatology for the diagnosis of a specific rheumatic disease. The IgG subclass deficiency term refers to a significant decrease in serum concentrations of one or more IgG subclasses in a patient whose total IgG concentration is normal, presenting recurrent bronchitis, sinusitis or otitis. We report the case of a female patient diagnosed with undifferentiated connective tissue disease associated with deficiency of IgG2 and IgG4.