Prevalence of neutropenia in the U.S. population: age, sex, smoking status, and ethnic differences

BACKGROUND

Benign reductions in neutrophil counts may be more common at certain ages and in certain ethnic groups and may be affected by sex and smoking status.

OBJECTIVE

To determine differences in neutrophil counts in the U.S. population according to ethnicity, age, sex, and smoking status.

DESIGN

Population-based, cross-sectional study.

SETTING

Various locations in the United States.

PARTICIPANTS

25,222 participants in the 1999 to 2004 National Health and Nutrition Examination Survey who were 1 year of age or older.

MEASUREMENTS

Complete blood counts and comparison of means and the proportion of participants with neutropenia.

RESULTS

Relative to white participants, black participants had lower leukocyte counts (mean difference, 0.89 x 10(9) cells/L; P < 0.001), lower neutrophil counts (0.83 x 10(9) cells/L; P < 0.001), and similar lymphocyte counts (0.022 x 10(9) cells/L; P = 0.36), whereas Mexican-American participants had slightly higher mean leukocyte counts (0.16 x 10(9) cells/L; P = 0.014), higher neutrophil counts (0.11 x 10(9) cells/L; P = 0.026), and higher lymphocyte counts (0.095 x 10(9) cells/L; P < 0.001). The prevalence of neutropenia (neutrophil count <1.5 x 10(9) cells/L) was 4.5% among black participants, 0.79% among white participants, and 0.38% among Mexican-American participants. The prevalence of neutropenia was higher among males and children younger than 5 years of age. Neutrophil counts less than 1.0 x 10(9) cells/L were observed in fewer than 1% of the overall sample (0.57% in black participants, 0.11% in white participants, and 0.08% in Mexican-American participants). Smoking was associated with higher leukocyte and neutrophil counts but had a smaller effect among black and Mexican-American participants than among white participants.

LIMITATION

Because estimates are based on single measures, fluctuations over time could not be determined.

CONCLUSIONS

In the United States, neutrophil counts are lower in black persons than in white persons and neutropenia is more prevalent in black persons. Neutrophil counts are slightly higher in Mexican-American persons than in white persons, and neutropenia is uncommon in both groups. The clinical implications of these findings are unclear, but they suggest that when determining the need for a diagnostic evaluation for neutropenia, clinicians should consider the patient's age, sex, ethnicity, and smoking status.

Active monitoring of 12,760 clozapine recipients in the UK and Ireland. Beyond pharmacovigilance

BACKGROUND

People prescribed clozapine for treatment-resistant schizophrenia have mandatory haematological monitoring through a case register for identifying reversible neutropenia.

AIMS

To quantify risk factors for agranulocytosis in subjects receiving clozapine.

METHOD

Data from 12,760 subjects registered to receive clozapine from January 1990 to April 1997 were analysed. Risk factors for agranulocytosis were quantified using a Cox proportional-hazards regression analysis.

RESULTS

The risk for agranulocytosis in Asian subjects was 2.4 times that in Caucasians (P = 0.03). There was an age-related increase in risk of 53% per decade (P = 0.0001).

CONCLUSIONS

The case register yielded valuable information for guiding research into the causes of the haematological reactions.

Benign ethnic neutropenia: what is a normal absolute neutrophil count?

Approximately 25% to 50% of persons of African descent and some ethnic groups in the Middle East have benign ethnic neutropenia, with low leukocyte and neutrophil counts. It is important to recognize the existence of this condition, the most common form of neutropenia throughout the world, and thus avoid both under-and overevaluation. Although there is no scientific basis for an absolute neutrophil count of 1.5x10(9)/L to be considered minimal, counts below this level are empirically regarded as inadequate in persons of all ethnic groups who are above the age of 1 year. Many individuals, however, maintain consistently low absolute neutrophil counts without evidence of increased susceptibility to infection or any other adverse effect. The important determination is not how many neutrophils are present in the peripheral blood, but whether the bone marrow is able to produce enough normally functioning cells when needed. A description of benign ethnic neutropenia, as set forth in this review, suggests that the lower limit now considered acceptable for the absolute neutrophil count should be readjusted downward for all ethnic groups.

Ethnic Neutropenia and Treatment Delay in African American Women Undergoing Chemotherapy for Early-Stage Breast Cancer

Disparities in breast cancer survival have been observed between African American and white women. There are also known differences in mean baseline white blood cell (WBC) count among racial and ethnic groups. If the WBC count falls below conventionally defined treatment thresholds for patients undergoing adjuvant chemotherapy, reduced doses or treatment delays may occur, which could lead to race-based differences in treatment duration. We used the tumor registry at Columbia-Presbyterian Medical Center to identify 1178 women with newly diagnosed stage I and II breast cancer from whom we collected base-line information for 73 African American women and 126 age- and tumor stage-matched white women. Of these women, 43 African American and 93 white women underwent adjuvant chemotherapy. African American women had statistically significantly lower WBC counts than white women at diagnosis (6.2 x 10(9)/L for African American women versus 7.4 x 10(9)/L for white women, difference = 1.2, 95% confidence interval [CI] = 0.2 to 1.2; P =.02) and after treatment (5.3 x 10(9)/L for African American women versus 6.4 x 10(9)/L for white women, difference = 1.1, 95% CI = 0.2 to 2.5; P =.03). Overall, African American women required a statistically significantly longer duration of treatment than white women (19 weeks versus 15 weeks, respectively, difference = 4 weeks, 95% CI = 0.5 to 7.2 weeks; P =.03). The lower baseline WBC counts and longer duration of treatment for early-stage breast cancer in African American women compared with those in white women result in lower dose intensity of treatment for African American women, possibly contributing to observed racial differences in breast cancer survival.

Benign familial leukopenia and neutropenia in different ethnic groups

Benign hereditary leukopenia-neutropenia has been reported in several ethnic groups, including Yemenite Jews, Blacks of South African extraction, West Indians and Arab Jordanians. The subjects with BFL were shown not to have an increased incidence of infections, and their response to infection did not differ from subjects having normal white blood cell counts. This study entails the report of two additional unrelated ethnic groups with familial neutropenia - Black Beduin and Falashah Jews. The familial nature of the phenomenon was confirmed. The suggested mechanism of this type of neutropenia is a defect in release of mature WBC from the bone marrow to the peripheral circulation. All ethnic groups thus far reported have tanned or dark skin. The significance of this common feature has still to be elucidated.

PXR, CAR and HNF4alpha genotypes and their association with pharmacokinetics and pharmacodynamics of docetaxel and doxorubicin in Asian patients

Previously studied candidate genes have failed to account for inter-individual variability of docetaxel and doxorubicin disposition and effects. We genotyped the transcriptional regulators of CYP3A and ABCB1 in 101 breast cancer patients from 3 Asian ethnic groups, that is, Chinese, Malays and Indians, in correlation with the pharmacokinetics and pharmacodynamics of docetaxel and doxorubicin. While there was no ethnic difference in docetaxel and doxorubicin pharmacokinetics, ethnic difference in docetaxel- (ANOVA, P=0.001) and doxorubicin-induced (ANOVA, P=0.003) leukocyte suppression was observed, with Chinese and Indians experiencing greater degree of docetaxel-induced myelosuppression than Malays (Bonferroni, P=0.002, P=0.042), and Chinese experiencing greater degree of doxorubicin-induced myelosuppression than Malays and Indians (post hoc Bonferroni, P=0.024 and 0.025). Genotyping revealed both PXR and CAR to be well conserved; only a PXR 5'-untranslated region polymorphism (-24381A>C) and a silent CAR variant (Pro180Pro) were found at allele frequencies of 26 and 53%, respectively. Two non-synonymous variants were identified in HNF4alpha (Met49Val and Thr130Ile) at allele frequencies of 55 and 1%, respectively, with the Met49Val variant associated with slower neutrophil recovery in docetaxel-treated patients (ANOVA, P=0.046). Interactions were observed between HNF4alpha Met49Val and CAR Pro180Pro, with patients who were wild type for both variants experiencing least docetaxel-induced neutropenia (ANOVA, P=0.030). No other significant genotypic associations with pharmacokinetics or pharmacodynamics of either drug were found. The PXR-24381A>C variants were significantly more common in Indians compared to Chinese or Malays (32/18/21%, P=0.035) Inter-individual and inter-ethnic variations of docetaxel and doxorubicin pharmacokinetics or pharmacodynamics exist, but genotypic variability of the transcriptional regulators PAR, CAR and HNF4alpha cannot account for this variability.

Duffy (Fy), DARC, and neutropenia among women from the United States, Europe and the Caribbean

Neutropenia associated with race/ethnicity has essentially been unexplained and, although thought to be benign, may affect therapy for cancer or other illnesses. A recent study linked a single nucleotide polymorphism (SNP) (rs2814778) in the Duffy antigen/receptor chemokine gene (DARC) with white blood cell count. We therefore analysed the association of the rs2814778 CC, TC and TT genotypes with absolute neutrophil count (ANC) among asymptomatic women from the Caribbean, Europe and the United States. Among 261 study participants, 33/47 women from Barbados/Trinidad-Tobago, 34/49 from Haiti, 26/37 from Jamaica, and 29/38 US-born black women, but only 4/50 from the Dominican Republic and 0/40 US- or European-born whites (P = 0.0001) had the CC genotype. In a linear regression model that included percentage African ancestry, national origin, cytokines, socio-economic factors and the ELA2 rs57834246 SNP, only the DARC rs2814778 genotype and C-reactive protein were associated with ANC (P < 0.0001). Women with the CC genotype had lower ANC than other women. Further research is needed on the associations of rs2814778 genotype with neutropenia and treatment delay in the setting of cancer. A better understanding of these associations may help to improve cancer outcomes among individuals of African ancestry.

Investigation of the effect of marathon running on leucocyte counts of subjects of different ethnic origins: relevance to the aetiology of ethnic neutropenia

Healthy subjects of African ancestry, including Afro-Caribbeans, have been observed to have lower total white cell counts and neutrophil counts than healthy Caucasian subjects. The cause of this ethnic neutropenia is unclear. We have previously found no evidence that increased margination of neutrophils is responsible. In this study, we have investigated mobilization of neutrophils from the bone marrow granulocyte reserve by endurance exercise. We investigated subjects of different ethnic origins before and after they had competed in a marathon race. Before the race, the neutrophil counts of Africans/Afro-Caribbeans were significantly lower than those of Caucasians (means 2.49 and 3.21 x 109/l respectively; P = 0.043). After the race, the difference was greater, as was the degree of significance (means 10.21 and 12.33 respectively; P = 0.017). The percentage increment was almost identical whereas the absolute increment was considerably less, although of marginal statistical significance (increment 7.72 and 9. 12 x 109/l respectively; P = 0.10). Similar changes were observed in the monocyte count. Before the race, the difference in the means was of marginal statistical significance (0.35 and 0.41 x 109/l respectively; P = 0.105), whereas after the race the difference was greater and was highly significant (means 0.75 and 1.05 x 109/l respectively; P = 0.001). These observations support the results of our earlier study, both of which suggested that ethnic neutropenia is likely to result from a diminished bone marrow reserve rather than being consequent on altered distribution of neutrophils within the blood stream.

Prediction of outcome in cancer patients with febrile neutropenia: a prospective validation of the Multinational Association for Supportive Care in Cancer risk index in a Chinese population and comparison with the Talcott model and artificial neural network

PURPOSE

We aimed to validate the Multinational Association for Supportive Care in Cancer (MASCC) risk index, and compare it with the Talcott model and artificial neural network (ANN) in predicting the outcome of febrile neutropenia in a Chinese population.

METHODS

We prospectively enrolled adult cancer patients who developed febrile neutropenia after chemotherapy and risk classified them according to MASCC score and Talcott model. ANN models were constructed and temporally validated in prospectively collected cohorts.

RESULTS

From October 2005 to February 2008, 227 consecutive patients were enrolled. Serious medical complications occurred in 22% of patients and 4% died. The positive predictive value of low risk prediction was 86% (95% CI = 81-90%) for MASCC score ≥ 21, 84% (79-89%) for Talcott model, and 85% (78-93%) for the best ANN model. The sensitivity, specificity, negative predictive value, and misclassification rate were 81%, 60%, 52%, and 24%, respectively, for MASCC score ≥ 21; and 50%, 72%, 33%, and 44%, respectively, for Talcott model; and 84%, 60%, 58%, and 22%, respectively, for ANN model. The area under the receiver-operating characteristic curve was 0.808 (95% CI = 0.717-0.899) for MASCC, 0.573 (0.455-0.691) for Talcott, and 0.737 (0.633-0.841) for ANN model. In the low risk group identified by MASCC score ≥ 21 (70% of all patients), 12.5% developed complications and 1.9% died, compared with 43.3%, and 9.0%, respectively, in the high risk group (p < 0.0001).

CONCLUSIONS

The MASCC risk index is prospectively validated in a Chinese population. It demonstrates a better overall performance than the Talcott model and is equivalent to ANN model.

Exercise induced mobilisation of the marginated granulocyte pool in the investigation of ethnic neutropenia

This study was designed to determine whether ethnic neutropenia is caused by an increased proportion of neutrophils being present in the marginated granulocyte pool. Thirty two healthy volunteers, half of whom were African or Afro-Caribbean and half of whom were white, exercised vigorously for 10 minutes on a step machine to mobilise granulocytes from the marginated granulocyte pool into the circulating granulocyte pool. The amount of work performed and the pulse rate response of the two ethnic groups were compared to determine whether the exercise carried out was comparable. A full blood count and an automated differential count were performed before and after the exercise. The haemoglobin concentration, platelet count, and absolute counts of total leucocytes and leucocyte subsets before and after exercise were compared in each individual and the values in the two ethnic groups both before and after exercise were compared. The absolute increase in neutrophils in the two ethnic groups was compared. The African/Afro-Caribbean group was found to have a reduced rather than enhanced ability to mobilise neutrophils from the marginated granulocyte pool. Therefore, increased margination of neutrophils is unlikely to be the cause of ethnic neutropenia.

Analyses of genome wide association data, cytokines, and gene expression in African-Americans with benign ethnic neutropenia

BACKGROUND

Benign ethnic neutropenia (BEN) is a hematologic condition associated with people of African ancestry and specific Middle Eastern ethnic groups. Prior genetic association studies in large population showed that rs2814778 in Duffy Antigen Receptor for Chemokines (DARC) gene, specifically DARC null red cell phenotype, was associated with BEN. However, the mechanism of this red cell phenotype leading to low white cell count remained elusive.

METHODS

We conducted an extreme phenotype design genome-wide association study (GWAS), analyzed ~16 million single nucleotide polymorphisms (SNP) in 1,178 African-Americans individuals from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study and replicated from 819 African-American participants in the Atherosclerosis Risk in Communities (ARIC) study. Conditional analyses on rs2814778 were performed to identify additional association signals on chromosome 1q22. In a separate cohort of healthy individuals with and without BEN, whole genome gene expression from peripheral blood neutrophils were analyzed for DARC.

RESULTS

We confirmed that rs2814778 in DARC was associated with BEN (p = 4.09×10-53). Conditioning on rs2814778 abolished other significant chromosome 1 associations. Inflammatory cytokines (IL-2, 6, and 10) in participants in the Howard University Family Study (HUFS) and Multi-Ethnic Study in Atherosclerosis (MESA) showed similar levels in individuals homozygous for the rs2814778 allele compared to others, indicating cytokine sink hypothesis played a minor role in leukocyte homeostasis. Gene expression in neutrophils of individuals with and without BEN was also similar except for low DARC expression in BEN, suggesting normal function. BEN neutrophils had slightly activated profiles in leukocyte migration and hematopoietic stem cell mobilization pathways (expression fold change <2).

CONCLUSIONS

These results in humans support the notion of DARC null erythroid progenitors preferentially differentiating to myeloid cells, leading to activated DARC null neutrophils egressing from circulation to the spleen, and causing relative neutropenia. Collectively, these human data sufficiently explained the mechanism DARC null red cell phenotype causing BEN and further provided a biologic basis that BEN is clinically benign.

Causes of incidental neutropenia in adulthood

The incidental discovery of neutropenia during routine blood counting represents a common problem for clinicians. However, there are no reported data of systematic evaluations of adults with incidental neutropenia. As such, this was the aim of the present study. Ninety-seven adults with incidental neutropenia were submitted to a clinical and laboratory approach including medical evaluation, complete blood count (CBC), serial CBC, direct and indirect antiglobulin test, bone marrow smear and biopsy, assessment of folate, vitamin B12 and iron status, serum liver enzymes, serum proteins, serological exams for hepatitis B and C virus, cytomegalovirus, mononucleosis, human immunodeficiency virus and toxoplasmosis, detection of lupus erythematosus cells, antinuclear and anti-DNA antibodies and rheumatoid factor, dosage of free thyroxin and thyrotropin, chest roentgenogram and abdominal echography. Chronic idiopathic neutropenia of adults was identified in 34.0% of the individuals, neutropenia due to exposure to chemical agents was seen in 16.5%, infectious diseases in 9.3%, autoimmune diseases in 9.3%, haematological diseases in 9.3%, thyroid disorders in 8.2%, ethnic neutropenia in 7.2%, drug-related neutropenia in 2.1%, cyclic neutropenia in 2.1% and iron deficiency in 2.1%. Recovery or improvement of the neutrophil count was seen upon treatment or recuperation from infectious, autoimmune, haematological and thyroid diseases and iron supplementation. We conclude that the evaluation of individuals with incidental neutropenia using a structured approach may make the identification of clinically silent diseases possible, and provide an opportunity for early treatment, avoiding complications of the diseases and consequences of neutropenia.

A novel HAX1 gene mutation in severe congenital neutropenia (SCN) associated with neurological manifestations

Autosomal recessive severe congenital neutropenia (SCN) results from a maturation arrest of granulopoiesis at the level of promyelocytes and apoptosis of myeloid cells. In SCN patients, mutations have been described in the HAX1 gene. Most of the SCN patients who carry nonsense mutations that are common to both transcript variants of the HAX1 gene also exhibit neurological deficits. This study describes an SCN patient with neurological manifestations including daily episodes of atonic seizures, learning disabilities, and developmental delay. Sequencing of the HAX1 gene of this SCN patient identified a novel nonsense c.463_464insC homozygous mutation in exon 3, which is common to both transcript variants of the gene. This mutation encodes for a p.Gln155ProfsX14 change and causes premature truncation of the HAX1 protein. Neutrophils isolated from the patient exhibited spontaneous apoptosis and loss of inner mitochondrial membrane potential, which were further enhanced upon treatment with hydrogen peroxide. This study adds to the spectrum of novel HAX1 gene mutations and disease manifestations in ethnically distinct SCN patients. Our report describes the only nonsense mutation in the HAX1 gene present in SCN patients of Arab origin.

'Neutropenia' in black west Indians

A prospective case control study routine haematological parameters was conducted in 294 healthy Black and White age/sex-matched subjects. The most important finding relevant to clinical practice was a reduction of total white cell count in Blacks due mainly to reduced neutrophil numbers. Twenty-one percent of sickle negative Blacks had white cell counts below the lowest value seen in Whites. The haemoglobin concentration, erythrocyte mean cell volume and monocyte count were also significantly lower amongst Blacks though lymphocyte counts were higher. The racial differences in haemoglobin and white count were not accounted for by differences in smoking and drinking habits. They were also found when Blacks with sickle cell trait were compared to age/sex-matched Whites and in others taking the oral contraceptive pill. Awareness of racial group should aid interpretation of routine tests and avoid unnecessary investigation of normal 'neutropenic' Blacks.

Leukocyte response to administration of corticosteroid in healthy black children with neutropenia

After a challenge with corticosteroid, increments in the absolute neutrophil count were > 50% in eight healthy black children with neutropenia, and > 2.0 x 10(9)/L (> 2000/mm3) in all but one child. Decrements in the absolute lymphocyte count mirrored the increments. Stimulation with hydrocortisone may be useful in characterizing ethnic neutropenia.

Alloimmune neonatal neutropenia in Australian aboriginals: an unrecognized disorder?

Alloimmune neonatal neutropenia (ANN) is reported for the first time in two Australian aboriginals. Both infants displayed the typical clinical features of ANN with profound neutropenia which persisted for 7 weeks and only minor infectious episodes. However, management strategies differed for the two infants because in one case (complicated by uncertain paternity) serological confirmation of ANN was not obtained until after recovery of the infant's neutrophil count. The maternal antibodies could not be assigned to known neutrophil antigen specificities and a new antigen may be involved. The antibodies were reactive with > 99% of neutrophils in a Caucasian population. Aboriginals comprise 1% of the total population of Australia and 1-2% of the obstetric population at our institution. Thus, ANN may be an unrecognized disorder in this ethnic group and a possible cause of neonatal infection and mortality.

Benign ethnic neutropenia in a South African population, and its association with HIV acquisition and adverse event reporting in an HIV vaccine clinical trial

Benign ethnic neutropenia (BEN) is defined as a neutrophil count of <1.5×109 cells/L in healthy individuals and is more common in populations of certain ethnicities, e.g. African or Middle Eastern ethnicity. Neutrophil values are commonly included in eligibility criteria for research participation, but little is known about the relationship between BEN, HIV acquisition, and the occurrence of adverse events during clinical trials. We investigated these relationships using data from an HIV vaccine efficacy trial of healthy adults from 5 South African sites. We analysed data from the double-blind, placebo-controlled, randomized trial HVTN 503, and its follow-on study HVTN 503-S to assess the prevalence of BEN, its association with HIV infection, and adverse event reporting. These data were then compared with a time- and age-matched, non-pregnant cohort from the National Health and Nutrition Examination Survey (NHANES) conducted between 2007-2008 in the United States (US). The 739 South African participants had a median age of 22.0 years (interquartile range = 20-26) and 56% (n = 412) were male. Amongst the US cohort of 845 participants, the median age was 26 (IQR: 21-30) and the majority (54%, 457/745) were also male. BEN was present at enrolment in 7.0% (n = 52) of South African participants (6% in the placebo group versus 8% in the vaccine group); 81% (n = 42) of those with BEN were male. Pretoria North had the highest prevalence of BEN (11.6%, 5/43), while Cape Town had the lowest (0.7%, 1/152). Participants with BEN had a lower median neutrophil count (1.3 vs. 3.2x109 cells/L; p<0.001) and BMI (20.8 vs. 22.3 kg/m2; p<0.001) when compared to those without BEN. A greater proportion of Black South Africans had neutrophil counts <1.5×109 cells/L compared to US non-Hispanic Whites from the NHANES cohort (7% [52/739] vs. 0.6% [3/540]; p<0.001). BEN did not increase the odds for HIV infection (adjusted odds ratio [aOR]: 1.364, 95% confidence interval [95% CI]: 0.625-2.976; p = 0.4351). However, female gender (aOR: 1.947, 95% CI: 1.265-2.996; p = 0.0025) and cannabis use (aOR: 2.192, 95% CI: 1.126-4.266; p = 0.0209) increased the odds of HIV acquisition. The incidence rates of adverse events were similar between participants in the placebo group with BEN, and those without: 12.1 (95% CI: 7.3-20.1) vs. 16.5 (95% CI: 14.6-18.7; p = 0.06) events per 100 person-years (py) were noted in the infections and infestations system organ class, respectively. The vaccine group had an event incidence rate of 19.7 (95% CI: 13.3-29.2) vs. 14.8 (95% CI: 13.0-16.8; p = 0.07) events per 100py in the group with, and without BEN, respectively. BEN is more prevalent in Black South Africans compared to US Non-Hispanic Whites. Our data do not support excluding populations from HIV vaccine trials because of BEN. BEN was not associated with increased risk for HIV infection or Adverse events on a vaccine trial. Predictors of HIV infection risk were females and cannabis use, underlying the continued importance of prevention programmes in focusing on these populations.

Chronic benign neutropenia among Chinese children

OBJECTIVE

To delineate the clinical behaviour of chronic benign neutropenia in Chinese children in Hong Kong.

DESIGN

Retrospective study.

SETTING

University teaching hospital, Hong Kong.

PATIENTS

All infants and children with absolute neutrophil count of 1.5 x 10(9) /L or lower for more than 3 months.

MAIN OUTCOME MEASURES

Development of significant infection, and achievement of remission.

RESULTS

Twenty-four children with chronic benign neutropenia were identified between 1992 and 2001. Their median age of diagnosis was 9 months. The mean (standard deviation) initial absolute neutrophil count was 0.28 x 10(9) /L (0.24 x 10(9) /L). Twenty-three patients presented with infection. Of the 19 patients tested, four (21%) were positive for anti-neutrophil antibodies. Bone marrow examination was performed in 17 patients: nine had normal results, but six showed evidence of peripheral consumption, one showed late maturation arrest at band stage, and one showed phagocytosis of myeloid cells by histiocytes. The overall hospitalised infection rate was 51.6 episodes per 1000 patient-months. Ten percent of cases were considered 'significant' infections and required hospital admission with either surgical intervention or intravenous therapy (antibiotics or fluid replacement). In the first year of diagnosis, more than 80% of patients had their lowest absolute neutrophil count (mean, 0.16 x 10(9) /L; standard deviation, 0.11 x 10(9) /L). Granulocyte-colony stimulating factor was used to treat three patients and induced transient elevation of absolute neutrophil count in all three. The projected remission rate was 55.4% at 3 years. Even for those with persistent disease, there was significant recovery in absolute neutrophil count to a mean of 0.5 x 10(9) /L (P<0.01).

CONCLUSIONS

Patients with chronic benign neutropenia experienced a relatively benign clinical course regardless of their remission status. Only a small proportion of patients developed significant infections. A multi-centre prospective study may help identify predictive factors of remission.

[Benign ethnic neutropenia; an unrecognised cause of leukopenia in negroid patients]

Leukopenia has a high incidence and is usually a reason for additional testing. Benign ethnic neutropenia is a relatively common cause of neutropenia in the negroid population. It can be the cause of aberrant laboratory results in negroid patients. A 55-year-old woman from Ghana was referred to the outpatient clinic because of malaise, leukopenia and neutropenia. Viral infection, haematological malignancy, auto-immune disease and vitamin deficiency were considered, but could not be confirmed by additional testing. Upon further investigation, the neutropenia in this patient was found to have existed for years. Moreover, our patient's son also had asymptomatic leukopenia. Therefore, benign ethnic neutropenia was considered the most likely diagnosis. Serological analysis of the patient's erythrocytes revealed the absence of Duffy (Fy) blood group antigens Fy(a) and Fy(b), which is associated with benign ethnic neutropenia.