(See also Overview of Immunodeficiency Disorders Overview of Immunodeficiency Disorders Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more and Approach to the Patient With an Immunodeficiency Disorder Approach to the Patient With Suspected Immunodeficiency Immunodeficiency typically manifests as recurrent infections. However, recurrent infections are more likely to have causes other than immunodeficiency (eg, inadequate treatment, resistant organisms... read more ).
Selective antibody deficiency with normal immunoglobulins (SADNI) is a primary immunodeficiency disorder Primary Immunodeficiencies Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more . It is one of the most common immunodeficiencies that manifests with recurrent sinopulmonary infections. Selective antibody deficiencies can occur in other disorders, but SADNI is a primary disorder in which deficient response to polysaccharide antigens is the only abnormality (see table Humoral Immunity Deficiencies Humoral immunity deficiencies Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more ). The inheritance and pathophysiology have not been elucidated, but some evidence suggests that the cause may be inherited molecular abnormalities.
A subset of patients with SADNI initially have an appropriate response to polysaccharide antigen but lose antibody titers within 6 to 8 months (called SADNI memory phenotype).
Patients have recurrent sinopulmonary infections and sometimes manifestations that suggest atopy (eg, chronic rhinitis, atopic dermatitis Atopic Dermatitis (Eczema) Atopic dermatitis is a chronic relapsing inflammatory skin disorder with a complex pathogenesis involving genetic susceptibility, immunologic and epidermal barrier dysfunction, and environmental... read more 
, asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more ). Severity of the disorder varies.
Young children may have a form of SADNI that resolves spontaneously over time.
Diagnosis of SADNI
Because healthy children < 2 years can have recurrent sinopulmonary infections and weak responses to polysaccharide vaccines, testing for SADNI is not done unless patients are > 2 years. Then, levels of IgG, IgA, IgM, and IgG subclasses and responses to vaccines are measured. The only abnormality in laboratory testing is a deficient response to polysaccharide vaccines (eg, pneumococcal vaccine). Responses to protein vaccines are normal.
Treatment of SADNI
Patients should be vaccinated with the pneumococcal conjugate (eg, 13-valent) vaccine Pneumococcal Vaccine Pneumococcal disease (eg, otitis media, pneumonia, sepsis, meningitis) is caused by some of the > 90 serotypes of Streptococcus pneumoniae (pneumococci). Vaccines are directed against many of... read more .
Sinopulmonary infections and atopic manifestations are treated aggressively. Uncommonly, when infections continue to recur, prophylactic antibiotics (eg, amoxicillin, trimethoprim/sulfamethoxazole) can be given.
Rarely, when infections recur frequently despite prophylactic antibiotics, immune globulin Replacement of missing immune components Immunodeficiency typically manifests as recurrent infections. However, recurrent infections are more likely to have causes other than immunodeficiency (eg, inadequate treatment, resistant organisms... read more replacement therapy can be given.
