What causes low white cell count
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Causes of Low White Cell Count
Genetic Factors and Ethnic Variations in White Blood Cell Count
Genetic factors play a significant role in determining white blood cell (WBC) count. Research has shown that individuals of African descent often have lower WBC counts compared to those of European descent. This difference is largely attributed to a genetic variant in the Duffy antigen receptor for chemokines (DARC) gene located on chromosome 1q. This variant, known as the Duffy Null polymorphism (SNP rs2814778), is highly prevalent in individuals of African ancestry and is associated with lower WBC and neutrophil counts 16. This genetic predisposition explains approximately 20% of the population variation in WBC among African Americans .
Polygenic Predisposition and Clinical Implications
A polygenic predisposition to lower WBC counts, which involves multiple genetic variants, also contributes to variations in WBC levels among individuals. This polygenic score for WBC count (PGSWBC) has been linked to a decreased likelihood of identifying pathology on bone marrow biopsies performed for low WBC counts. However, it also increases the risk of leukopenia (low WBC count) when treated with chemotherapeutic or immunosuppressant drugs, and may lead to discontinuation of treatments like azathioprine due to adverse effects .
Aging and Immune System Changes
Aging is another factor that influences WBC count. As individuals age, there is a decline in the number and quality of lymphoid progenitor cells, which are crucial for the immune response. This decline is thought to be due to inherent programmed processes within stem and progenitor cells, acting like an internal clock that controls their functionality and lifespan. Consequently, older adults, particularly those aged 75 and above, often exhibit lower WBC counts, which can serve as an indicator of survival .
Inflammation and Disease Associations
Inflammation and certain diseases are also associated with changes in WBC count. For instance, higher WBC counts have been linked to an increased risk of type 2 diabetes (T2D), suggesting that inflammation might play a role in the development of T2D. Conversely, low WBC counts can be indicative of underlying health issues, such as infections or systemic inflammation, which are common in conditions like cancer or severe illnesses requiring intensive care 789.
Conclusion
Low white cell count can be caused by a variety of factors, including genetic predispositions, aging, and underlying health conditions. Genetic variations, particularly those prevalent in certain ethnic groups, play a significant role in determining WBC levels. Additionally, polygenic factors and the natural decline in immune function with age contribute to lower WBC counts. Understanding these causes is crucial for diagnosing and managing conditions associated with low WBC counts, and for tailoring treatments to individual genetic profiles.
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