Can Chinese individuals have genetically low White Blood Cell (WBC) counts?

Genetic Basis for Low White Blood Cell Counts in Chinese Individuals

Yes, Chinese individuals can have genetically lower white blood cell counts (WBC) compared to other ethnic groups, which is considered a normal variant and not necessarily pathological.

Genetic Basis for Ethnic Neutropenia

• The phenomenon of ethnic neutropenia has been well-documented across multiple racial and ethnic groups, including individuals of Chinese and East Asian descent 1.

• The primary genetic mechanism involves a single-nucleotide polymorphism (SNP) in the Duffy antigen receptor for chemokine (DARC) gene, specifically rs2814778, which has been strongly associated with lower WBC counts in certain ethnic groups 1.

• This genetic variation affects the release of mature white blood cells from the bone marrow into peripheral circulation, resulting in consistently lower WBC counts without increased susceptibility to infections 2.

Evidence from Population Studies

• Research examining complete blood count (CBC) reference intervals across different ethnic groups has shown significant differences in neutrophil counts among racial/ethnic groups 3.

• A 2019 study of multiethnic populations found that neutrophil, lymphocyte, and eosinophil counts showed significant differences among White, Black, Hispanic, and Asian populations, supporting the need for race/ethnicity-specific CBC reference intervals 3.

• Another study examining hematologic parameters across racial and ethnic subgroups found that Asians had higher red blood cell counts but lower lymphocyte and monocyte counts compared to other ethnic groups 4.

Clinical Implications

• Lower WBC counts in Chinese individuals are typically benign and not associated with increased infection risk or other adverse health outcomes 2.

• This condition is often referred to as "benign ethnic neutropenia" and should not be confused with pathological causes of neutropenia 2.

• When evaluating WBC counts in Chinese patients:

  • Consider using ethnicity-specific reference ranges rather than standard ranges derived from predominantly White populations
  • Avoid unnecessary diagnostic testing or interventions for mildly low WBC counts that may represent normal variation
  • Monitor trends over time rather than focusing on absolute values

Distinguishing Benign Ethnic Neutropenia from Pathological Causes

• Key features of benign ethnic neutropenia:

  • Stable WBC counts over time
  • No history of recurrent or severe infections
  • Normal bone marrow examination (if performed)
  • Family history of similar findings

• Warning signs that may indicate pathological neutropenia:

  • Progressive decline in WBC counts
  • Associated symptoms (fever, fatigue, recurrent infections)
  • Abnormalities in other blood cell lines
  • Recent medication changes that could affect WBC

Practical Recommendations

• When interpreting CBC results in Chinese patients:

  1. Consider ethnicity-specific reference ranges
  2. Evaluate the patient's baseline if previous results are available
  3. Assess for symptoms or signs of infection or other hematologic disorders
  4. Consider family history of low WBC counts

• Avoid unnecessary referrals to hematology or extensive workups for mildly decreased WBC counts in otherwise healthy Chinese individuals with stable counts and no concerning symptoms.

This genetic variation represents normal human diversity rather than pathology and recognizing it can prevent unnecessary testing and patient anxiety.