Btk is the protein affected in XLA, a disease identified as a B cell differentiation defect. Btk is crucial for B cell differentiation and activation, but its role in other cells is not fully understood. This review focuses on the function of Btk in monocytes, neutrophils, and platelets and the receptors and signaling cascades in such cells with which Btk is associated.

diagnosis of primary immunodeficiency diseases (PID) is still a challenge in many countries in Latin America (LA), especially those that face social and economic problems. The creation of a society was fundamental to combine efforts that resulted in an effective educational program, establishment of a registry and a network to improve diagnosis. Areas covered: The focus of this article is to portray the scenario of PID in LA covering different aspects from different countries. For this, a questionnaire was sent to countries that participate in the Latin American Society for Immunodeficiencies (LASID) registry, with questions related to PID challenges in LA. We realized that today the greatest challenge is the availability of laboratory tests to investigate newly described PIDs. Expert commentary: Despite being faced with many difficulties, the Latin America Society for Immunodeficiencies is supporting clinical immunologists throughout the continent, which has resulted in a greater awareness of these diseases and an increase in the number of diagnosis.

Our results demonstrate a predominantly inflammatory response in XLA patients after LPS stimulation and suggest a deregulation of TLR signaling in the absence of Btk. This response may be influenced by environmental factors.

Delayed diagnosis and atypical manifestations in XLA might be related to mutation type and BTK expression.

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Autosomal recessive (AR) DOCK8 deficiency is a well-known actinopathy, a combined primary immune deficiency with impaired actin polymerization that results in altered cell mobility and immune synapse. DOCK8-deficient patients present early in life with eczema, viral cutaneous infections, chronic mucocutaneous candidiasis, bacterial pneumonia, and abscesses, together with eosinophilia, thrombocytosis, lymphopenia, and variable dysgammaglobulinemia that usually includes Hyper-IgE. In fact, before its genetic etiology was known, patients were described as having a form of Hyper-IgE syndrome, a name now deprecated in favor of genetic defects. We describe a school-age male patient with a clinical picture suggestive of DOCK8 deficiency, except for high serum IgE or a family history: early onset, failure to thrive, eczema, warts, condyloma, bronchiolitis, pneumonia, recurrent otitis media, bronchiectasis, candidiasis, leukocytosis, eosinophilia, high IgA, low IgG, and low CD4+ T cells. We were able to confirm the diagnosis through protein expression and whole-exome sequencing. We review the clinical, laboratory, and genetic features of 200 DOCK8-deficient patients; at least 4 other patients have had no elevated IgE, and about 40% do not have Hyper-IgE (above 1,000 IU/mL). Despite this, the constellation of signs, symptoms, and findings allow the suspicion of DOCK8 deficiency and other actinopathies.

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