विवरण
Primary immunodeficiency disorders in children are a group of rare genetic conditions that impair the immune system, making it difficult for the body to fight infections. Children with PIDs may experience frequent, severe, or unusual infections that can affect various parts of the body, such as the respiratory system, skin, and digestive tract. Early diagnosis is crucial, as timely treatment with immunoglobulin therapy, antibiotics, and sometimes bone marrow transplants can help manage symptoms and prevent complications. Genetic counseling and family education are also important aspects of care to support the child's long-term health. Advances in gene therapy offer hope for more definitive treatments in the future.
सारांश
- Primary immunodeficiency disorders (PIDs), also known as inborn errors of immunity, are genetic in origin, inherited from parents to children, and often involve defects in single genes (monogenic). The frequency of PID diagnosis is increasing due to advancements in genetic testing, with over 430 documented cases. These disorders are often underdiagnosed, and their incidence ranges from 1 in 2,000 to 1 in 5,000. Antibody defects are the most common type, followed by combined immunodeficiencies and phagocytic defects.
- Indications for suspecting PID include repeated infections (ear, sinus, lung, GI), failure to thrive, prolonged antibiotic use, persistent oral thrush, deep-seated abscesses, and a family history of immunodeficiency. Suspicion also arises with unusual, recurrent, or chronic organisms, severe systemic infections, infections at unusual sites, unusual pathogens, and unexplained bronchiectasis or autoimmune disorders.
- A clinical approach to PID involves considering the age of presentation, the type of organism causing infection, and a detailed family history. PID onset before six months is often linked to T-cell defects, while onset after six months is more commonly associated with B-cell defects. Pattern of infection analysis can point to specific deficiencies, such as antibody defects in sino-pulmonary or GI infections, and phagocytic or antibody deficiencies in abscesses.
- Laboratory diagnosis begins with a complete blood count (CBC) with differential, examining white blood cell (WBC) counts for neutropenia or leukocytosis, platelet counts for abnormalities like in Wiskott-Aldrich syndrome, and lymphocyte counts to identify T-cell deficiencies. Specific screening tests include immunoglobulin levels for antibody deficiencies, lymphocyte subset analysis for T-cell disorders, neutrophil function tests for phagocytic defects, and complement assays for complement deficiencies.
- Specific PID cases illustrate diagnostic approaches: Absent tonsils and recurrent sino-pulmonary infections suggest X-linked agammaglobulinemia, characterized by pan-hypogammaglobulinemia and absent B cells. Common variable immunodeficiency (CVID) presents later in life with hypogammaglobulinemia but with detectable B cells. Hyper-IgM syndrome is characterized by elevated IgM levels and deficient IgG, IgA, and IgE, due to impaired T-cell help for B-cell class switching.
- Severe Combined Immunodeficiency (SCID) is indicated by severe pneumonia and oral thrush, absent thymus on imaging, and profound lymphopenia. Chronic Granulomatous Disease (CGD) is suspected with recurrent abscesses and granuloma formation, with diagnosis confirmed by NBT or dihydrorhodamine (DHR) testing showing impaired neutrophil function. Wiskott-Aldrich Syndrome is an X-linked disorder characterized by thrombocytopenia, eczema, and susceptibility to infection, with small platelet volume.
- Leukocyte Adhesion Deficiency (LAD) should be considered in cases of high absolute neutrophil counts without infection, delayed umbilical cord separation, and recurrent bacterial infections without pus formation, confirmed by CD18 marker analysis. Management involves treating infections with antibiotics, immunoglobulin replacement therapy for antibody deficiencies, and hematopoietic stem cell transplantation for certain severe PID cases. Recognizing and appropriately managing complications such as severe infections, autoimmune disorders, and malignancies is crucial.
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