RESUMEN
<p><b>BACKGROUND</b>Common variable immunodeficiency (CVID) is one of the most common symptomatic primary immunodeficiency syndromes. The purpose of this article was to broaden our knowledge about CVID for better diagnosis and treatment.</p><p><b>METHODS</b>Clinical and immunological features of 40 Chinese patients with CVID were analyzed retrospectively.</p><p><b>RESULTS</b>The median age at onset was 11-year-old (range 4-51 years). The median age at diagnosis was 14.5-year-old (range 5-66 years). The average time of delay in diagnosis was 5.3 years (range 1-41 years). The most common main complaint was fever due to infections (35 cases, 87.5%). Pneumonia (28 cases, 70%) was the most common type of infections. Bronchiectasis was present in 6 patients (15%). Autoimmune disease was detected in 6 cases of CVID, and malignancy in 2 cases. The median total serum levels of IgG, IgA, and IgM at diagnosis were 1.07 g/L, 0.07 g/L, and 0.28 g/L, respectively. The percentages of CD3- /CD19 + B-cells were 1%-3.14%.</p><p><b>CONCLUSIONS</b>Infection is the most frequent presentation of CVID. Patients with unexplainable infections should receive further examination including serum immunoglobulin (Ig) and lymphocyte subset analysis. Regular and sufficient substitution with Ig is recommended.</p>