RESUMO
OBJECTIVE: To describe h- and g-indices benchmarks in pediatric subspecialties and general academic pediatrics. Academic productivity is measured increasingly through bibliometrics that derive a statistical enumeration of academic output and impact. The h- and g-indices incorporate the number of publications and citations. Benchmarks for pediatrics have not been reported. STUDY DESIGN: Thirty programs were selected randomly from pediatric residency programs accredited by the Accreditation Council for Graduate Medical Education. The h- and g-indices of department chairs were calculated. For general academic pediatrics, pediatric gastroenterology, and pediatric nephrology, a random sample of 30 programs with fellowships were selected. Within each program, an MD faculty member from each academic rank was selected randomly. Google Scholar via Harzing's Publish or Perish was used to calculate the h-index, g-index, and total manuscripts. Only peer-reviewed and English language publications were included. For Chairs, calculations from Google Scholar were compared with Scopus. RESULTS: For all specialties, the mean h- and g-indices significantly increased with academic rank (all P < .05) with the greatest h-indices among Chairs. The h- and g-indices were not statistically different between specialty groups of the same rank; however, mean rank h-indices had large SDs. The h-index calculation using different bibliographic databases only differed by ±1. CONCLUSION: Mean h-indices increased with academic rank and were not significantly different across the pediatric specialties. Benchmarks for h- and g-indices in pediatrics are provided and may be one measure of academic productivity and impact.
Assuntos
Bibliometria , Eficiência , Internato e Residência/estatística & dados numéricos , Pediatria/educação , Benchmarking , Educação de Pós-Graduação em Medicina , Humanos , Publicações , Editoração/estatística & dados numéricosRESUMO
Fetal hemoglobin (HbF) modulates the phenotype of sickle cell anemia by inhibiting deoxy sickle hemoglobin (HbS) polymerization. The blood concentration of HbF, or the number of cells with detectable HbF (F-cells), does not measure the amount of HbF/F-cell. Even patients with high HbF can have severe disease because HbF is unevenly distributed among F-cells, and some cells might have insufficient concentrations to inhibit HbS polymerization. With mean HbF levels of 5%, 10%, 20%, and 30%, the distribution of HbF/F-cell can greatly vary, even if the mean is constant. For example, with 20% HbF, as few as 1% and as many as 24% of cells can have polymer-inhibiting, or protective, levels of HbF of â¼10 pg; with lower HbF, few or no protected cells can be present. Only when the total HbF concentration is near 30% is it possible for the number of protected cells to approach 70%. Rather than the total number of F-cells or the concentration of HbF in the hemolysate, HbF/F-cell and the proportion of F-cells that have enough HbF to thwart HbS polymerization is the most critical predictor of the likelihood of severe sickle cell disease.
Assuntos
Anemia Falciforme/imunologia , Anemia Falciforme/terapia , Hemoglobina Fetal/imunologia , Adulto , Anemia Falciforme/sangue , Eritrócitos/citologia , Deleção de Genes , Haplótipos , Hemoglobina Falciforme/imunologia , Heterozigoto , Humanos , Hidroxiureia/uso terapêutico , Modelos Teóricos , Família Multigênica , Fenótipo , Polímeros/químicaRESUMO
During the past decade a large body of experimental and clinical studies has focused on the hypothesis that nitric oxide (NO) depletion by plasma hemoglobin in the microcirculation plays a central role in the pathogenesis of many manifestations of sickle cell disease (SCD), particularly pulmonary hypertension. We have carefully examined those studies and believe that the conclusions drawn from them are not adequately supported by the data. We agree that NO depletion may well play a role in the pathophysiology of other hemolytic states such as paroxysmal nocturnal hemoglobinuria, in which plasma hemoglobin concentrations are often at least an order of magnitude greater than in SCD. Accordingly, we conclude that clinical trials in SCD designed to increase the bioavailability of NO or association studies in which SCD clinical manifestations are related to plasma hemoglobin via its surrogates should be viewed with caution.
Assuntos
Anemia Falciforme/fisiopatologia , Hipertensão Pulmonar/etiologia , Modelos Biológicos , Óxido Nítrico/deficiência , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/complicações , Anemia Falciforme/tratamento farmacológico , Animais , Criança , Ensaios Clínicos como Assunto , Modelos Animais de Doenças , Ecocardiografia Doppler , Endotélio Vascular/fisiopatologia , Reações Falso-Positivas , Feminino , Hemoglobinas/análise , Hemoglobinas/química , Hemoglobinúria Paroxística/complicações , Hemólise , Humanos , Hidroxiureia/farmacologia , Hidroxiureia/uso terapêutico , Hipertensão Pulmonar/sangue , Hipertensão Pulmonar/diagnóstico por imagem , Hipertensão Pulmonar/fisiopatologia , L-Lactato Desidrogenase/sangue , Úlcera da Perna/etiologia , Úlcera da Perna/fisiopatologia , Masculino , Microcirculação , Estudos Multicêntricos como Assunto , Óxido Nítrico/administração & dosagem , Óxido Nítrico/sangue , Óxido Nítrico/fisiologia , Óxido Nítrico/uso terapêutico , Priapismo/etiologia , Priapismo/fisiopatologia , Tromboembolia/etiologia , Tromboembolia/fisiopatologia , Insuficiência da Valva Tricúspide/diagnóstico por imagem , Insuficiência da Valva Tricúspide/etiologia , Insuficiência da Valva Tricúspide/fisiopatologiaRESUMO
BACKGROUND: The traditional role of the faculty inpatient attending providing clinical care and effectively teaching residents and medical students is threatened by increasing documentation requirements, pressures to increase clinical productivity, and insufficient funding available for medical education. In order to sustain and improve clinical education on a general pediatric inpatient service, we instituted a comprehensive program change. Our program consisted of creating detailed job descriptions, setting clear expectations, and providing salary support for faculty inpatient attending physicians serving in clinical and educational roles. This study was aimed at assessing the impact of this program change on the learners' perceptions of their faculty attending physicians and learners' experiences on the inpatient rotations. METHODS: We analyzed resident and medical student electronic evaluations of both clinical and teaching faculty attending physician characteristics, as well as resident evaluations of an inpatient rotation experience. We compared the proportions of "superior" ratings versus all other ratings prior to the educational intervention (2005-2006, baseline) with the two subsequent years post intervention (2006-2007, year 1; 2007-2008, year 2). We also compared medical student scores on a comprehensive National Board of Medical Examiners clinical subject examination pre and post intervention. RESULTS: When compared to the baseline year, pediatric residents were more likely to rate as superior the quality of didactic teaching (OR=1.7 [1.0-2.8] year 1; OR=2.0 [1.1-3.5] year 2) and attendings' appeal as a role model (OR=1.9 [1.1-3.3] year 2). Residents were also more likely to rate as superior the quality of feedback and evaluation they received from the attending (OR=2.1 [1.2-3.7] year 1; OR=3.9 [2.2-7.1] year 2). Similar improvements were also noted in medical student evaluations of faculty attendings. Most notably, medical students were significantly more likely to rate feedback on their data gathering and physical examination skills as superior (OR=4.2 [2.0-8.6] year 1; OR=6.4 [3.0-13.6] year 2). CONCLUSIONS: A comprehensive program which includes clear role descriptions along with faculty expectations, as well as salary support for faculty in clinical and educational roles, can improve resident and medical student experiences on a general pediatric inpatient service. The authors provide sufficient detail to replicate this program to other settings.
Assuntos
Educação Médica/normas , Docentes de Medicina/normas , Hospitais Pediátricos , Hospitais Universitários , Internato e Residência/normas , Descrição de Cargo , Corpo Clínico Hospitalar/educação , Corpo Clínico Hospitalar/normas , Pediatria/educação , Salários e Benefícios , Ensino , Atitude do Pessoal de Saúde , Baltimore , Competência Clínica/normas , Currículo/normas , Retroalimentação , Humanos , Melhoria de Qualidade/normas , Conselhos de Especialidade Profissional , Estudantes de Medicina/psicologiaRESUMO
Increasing hemoglobin F (HbF) appears to be beneficial for patients with sickle cell anemia. We previously demonstrated that daily, oral sodium phenylbutyrate (OSPB) induces HbF synthesis in pediatric and adult patients with hemoglobin SS (HbSS). The high doses and need for daily therapy, however, have limited its use. Here, we report a patient treated with pulsed-dosing of OSPB for over 3 years. This patient developed a modest, but sustained elevation in HbF over the course of therapy without side effects. Although larger studies are needed, this case demonstrates that pulsed-dosing with OSPB enhances HbF synthesis.
Assuntos
Anemia Falciforme/sangue , Anemia Falciforme/tratamento farmacológico , Hemoglobina Fetal/metabolismo , Fenilbutiratos/administração & dosagem , Administração Oral , Criança , Esquema de Medicação , Humanos , MasculinoRESUMO
OBJECTIVE: In vivo, several drugs have been shown to increase fetal hemoglobin (HbF), including 5-azacytidine (AZA), sodium butyrate (SB), and hydroxyurea (HU). Studies in K562 cells suggest that cyclic guanosine monophosphate (cGMP) is required for HbF induction; however, the role of cyclic nucleotides in HbF induction in primary erythroid cultures has not been established. METHODS: CD34-selected peripheral blood monocytes cultured in a semi-solid serum-free system that mimics in vivo F-cell production are utilized to explore the role of cyclic adenosine monophosphate (cAMP) and cGMP in HbF induction in response to HU, AZA, and SB. RESULTS: In serum-free CD34 cultures, HU, SB, and AZA all markedly stimulate FNRBC production up to 30-fold, associated with induction of gamma-globin mRNA and total HbF protein. Guanylate cyclase inhibition results in only minimal blunting of HbF induction by each agent. In contrast, adenylate cyclase inhibition markedly reduces HU, SB, and AZA-mediated FNRBC induction and gamma-globin mRNA induction. The adenylate cyclase activator forskolin modestly induces FNRBC production and augments the action of standard induction agents. HU, AZA, and SB, however, fail to significantly stimulate adenylate cyclase themselves. CONCLUSIONS: In human CD34(+) cultures, cAMP production is required for full induction of HbF by HU, SB, and AZA, while perturbation of cGMP production has only minimal effects. These findings are in marked contrast to data in K562 cells where cGMP production is critical for HbF induction while cAMP stimulation blunts HbF response, and suggest that these agents may share a common induction pathway.
Assuntos
Antígenos CD34 , Antidrepanocíticos/farmacologia , Azacitidina/análogos & derivados , Butiratos/farmacologia , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Inibidores Enzimáticos/farmacologia , Hemoglobina Fetal/biossíntese , Hidroxiureia/farmacologia , Monócitos/metabolismo , Adenilil Ciclases/metabolismo , Azacitidina/farmacologia , Colforsina/farmacologia , Decitabina , Células Eritroides/citologia , Células Eritroides/metabolismo , Humanos , Células K562 , Monócitos/citologia , RNA Mensageiro/biossínteseRESUMO
The "7 Great Achievements in Pediatric Research" campaign noted discoveries in the past 40 years that have improved child and adult health in the United States and around the globe. This article predicts the next 7 great pediatric research advancements, including new immunizations, cancer immunotherapy, genomic discoveries, identification of early antecedents of adult health, impact of specific social-environmental influences on biology and health, quality improvement science, and implementation and dissemination research to reduce global poverty. It is an extraordinary time of new research tools that include electronic health records, technological ability to manage big data and measure "omics," and new functional and structural imaging modalities. These tools will discern mechanisms leading to health and disease with new prevention targets and cures. This article further discusses the challenges and opportunities to accelerate these exciting pediatric research discoveries to improve the lives of children and the adults they will become.
Assuntos
Pesquisa Biomédica/tendências , Pediatria/tendências , Logro , Criança , Atenção à Saúde/normas , Atenção à Saúde/tendências , Genômica/tendências , Saúde Global/tendências , Humanos , Imunização/tendências , Imunoterapia/tendências , Neoplasias/terapia , Pobreza/prevenção & controle , Pobreza/tendências , Melhoria de QualidadeAssuntos
Modelos Biológicos , Medicina Preventiva/métodos , Adulto , Idade de Início , Evolução Biológica , Peso ao Nascer , Criança , Doença das Coronárias/mortalidade , Epigênese Genética , Feminino , Variação Genética , Humanos , Mortalidade Infantil , Recém-Nascido , Masculino , Neoplasias/mortalidade , GravidezRESUMO
UNLABELLED: Hospital relocation is a highly complex undertaking, which has the potential to interrupt operations and poses risks for patients, staff, and providers. Little is known how hospital relocation impacts on workflow and communication. METHODS: Using existing Electronic Health Record (EHR) data we determined time from medication ordering to first dose administration as a proxy for well-being of the medication process during a five months window surrounding the relocation of a 205-bed children's hospital. RESULTS: Overall performance of the medication process has declined slightly. We identified regional (unit) differences with the pediatric intensive care unit, which had the most significant changes to its workflow, experiencing a more than doubling of the time from ordering to medication administration. Overall, there was no significant difference in time-sensitive medication administration times. Evaluating the medication ordering-dispensing-administration process through readily available EHR data demonstrated that the impact of a hospital' s relocation on workflow and communication can be successfully monitored.
Assuntos
Registros Eletrônicos de Saúde/estatística & dados numéricos , Hospitalização/estatística & dados numéricos , Hospitais Pediátricos/estatística & dados numéricos , Sistemas de Registro de Ordens Médicas/estatística & dados numéricos , Erros de Medicação/estatística & dados numéricos , Transferência de Pacientes/estatística & dados numéricos , Fluxo de Trabalho , Adolescente , Criança , Pré-Escolar , Feminino , Hospitais Pediátricos/classificação , Humanos , Lactente , Recém-Nascido , Masculino , Maryland , Sistemas de Registro de Ordens Médicas/classificação , Erros de Medicação/prevenção & controle , Transferência de Pacientes/classificação , Garantia da Qualidade dos Cuidados de Saúde/métodos , Adulto JovemRESUMO
Although pediatric research enjoyed significant benefits during the National Institutes of Health (NIH) doubling era, the proportion of the NIH budget devoted to the pediatric-research portfolio has declined overall. In light of this declining support for pediatric biomedical research, the Federation of Pediatric Organizations held a topic symposium at the 2009 Pediatric Academic Societies annual meeting as a forum for discussion of the past and future states of funding, the rationale for directing public funds toward the understanding of child health and disease, and new programs and paradigms for promoting child health research. This report of the symposium is intended to disseminate more broadly the information presented and conclusions discussed to encourage those in the child health research community to exert influence with policy makers to increase the allocation of national funding for this underfunded area.
Assuntos
Proteção da Criança/economia , Política de Saúde , Promoção da Saúde/organização & administração , Pediatria/economia , Apoio à Pesquisa como Assunto , Pré-Escolar , Redução de Custos , Promoção da Saúde/economia , Humanos , Disseminação de Informação , National Institutes of Health (U.S.) , Pediatria/organização & administração , Estados UnidosRESUMO
The multicenter study of hydroxyurea (MSH) in sickle-cell anemia (SCA) demonstrated that patients treated with hydroxyurea (HU) had a 44% decrease in hospitalizations when compared with those taking placebo. A subsequent study looking at the cost-effectiveness of HU showed that decreased hospitalizations for painful crisis accounted for the majority of cost savings in those taking HU. The purpose of this study was to examine whether the expected decrease in hospital utilization occurred after the approval of HU in Maryland. We used data collected by the Maryland Health Services Cost Review Commission to obtain SCA discharge data for Maryland from FY1995 through FY2003. We also reviewed the inpatient and outpatient charts of all adults with SCA admitted to a large university hospital during 2003. Hospitalization rates for adults with SCA in Maryland have increased significantly since approval of HU. While the total costs of inpatient care in Maryland are estimated to have increased by 31% above inflation from 1995 to 2003, the costs of inpatient care for adult SCA patients has increased by almost 60% above inflation. By comparison, there has been no significant increase in the pediatric hospitalization rate. We found that 70% of patients in one hospital who were appropriate candidates for HU were not taking the medication. Hospital utilization among adults with SCA has increased significantly. There are likely many factors that have played a role in this increase. One factor that appears to be involved is the underutilization of HU.
Assuntos
Anemia Falciforme/economia , Antidrepanocíticos/economia , Hospitalização/economia , Hidroxiureia/economia , Adolescente , Adulto , Anemia Falciforme/tratamento farmacológico , Antidrepanocíticos/uso terapêutico , Criança , Pré-Escolar , Custos e Análise de Custo/métodos , Bases de Dados Factuais , Feminino , Hospitais Universitários/economia , Humanos , Hidroxiureia/uso terapêutico , Masculino , Maryland , Aceitação pelo Paciente de Cuidados de Saúde , Educação de Pacientes como Assunto , Estudos RetrospectivosRESUMO
This study was designed to determine if low doses of oral sodium phenylbutyrate (SPB) induce hemoglobin F (HbF) synthesis in children with hemoglobin SS (HbSS). We treated 8 children with HbSS over a period of 5-30 weeks. The initial dose (1.0 g/d) was increased weekly (by 1.0 g/d) until F-reticulocytes doubled. All patients showed an increase in F-reticulocytes (P = 0.002) that was dose-dependent (P = 0.001). Three of 5 patients who continued oral SPB for more than 10 weeks had substantial increases in HbF. We conclude that lower dose SPB is effective in inducing HbF synthesis in some children with HbSS. Further trials are warranted to determine the optimal treatment regimen.
Assuntos
Anemia Falciforme/sangue , Anemia Falciforme/tratamento farmacológico , Hemoglobina Fetal/biossíntese , Fenilbutiratos/uso terapêutico , Administração Oral , Adolescente , Criança , Pré-Escolar , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Cooperação do Paciente , Fatores de TempoRESUMO
Orally bioactive compounds that induce gamma globin gene expression at tolerable doses are needed for optimal treatment of the beta-hemoglobinopathies. Short-chain fatty acids (SCFAs) of 2 to 6 carbons in length induce gamma globin expression in animal models, and butyrate, phenylbutyrate, and valproate induce gamma globin in human patients. The usefulness of these compounds, however, is limited by requirements for large doses because of their rapid metabolism and their tendency to inhibit cell proliferation, which limits the pool of erythroid progenitors in which gamma globin can be induced. Selected short-chain fatty acid derivatives (SCFADs) were recently found to induce gamma globin and to stimulate the proliferation of hematopoietic cells in vitro. These SCFADs are now evaluated in vivo in nonanemic transgenic mice containing the human beta globin gene locus and in anemic phlebotomized baboons. In mice treated with a SCFAD once daily for 5 days, gamma globin mRNA increased 2-fold, reticulocytes increased 3- to 7-fold, and hematocrit levels increased by 27%. Administration of 3 SCFADs in anemic baboons increased F-reticulocytes 2- to 15-fold over baseline and increased total hemoglobin levels by 1 to 2 g/dL per week despite ongoing significant daily phlebotomy. Pharmacokinetic studies demonstrated 90% oral bioavailability of 2 SCFADs, and targeted plasma levels were maintained for several hours after single oral doses equivalent to 10% to 20% of doses required for butyrate. These findings identify SCFADs that stimulate gamma globin gene expression and erythropoiesis in vivo, activities that are synergistically beneficial for treatment of the beta hemoglobinopathies and useful for the oral treatment of other anemias.
Assuntos
Eritropoese/efeitos dos fármacos , Ácidos Graxos Voláteis/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Globinas/biossíntese , Anemia/genética , Anemia/metabolismo , Animais , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/metabolismo , Cromossomos Artificiais de Levedura , Avaliação Pré-Clínica de Medicamentos , Células Precursoras Eritroides/citologia , Células Precursoras Eritroides/efeitos dos fármacos , Eritropoetina/farmacologia , Ácidos Graxos Voláteis/farmacocinética , Genes Reporter , Globinas/genética , Meia-Vida , Humanos , Luciferases/biossíntese , Luciferases/genética , Camundongos , Camundongos Transgênicos , Papio , Fenilpropionatos/farmacologia , Regiões Promotoras Genéticas , Proteínas Recombinantes , Contagem de Reticulócitos , TransfecçãoRESUMO
OBJECTIVE: To investigate the role of hematological indices, socioeconomic status, and morbidity in prepubertal growth in homozygous sickle cell (SS) disease from birth to 9 years at the sickle cell clinic of the University Hospital of the West Indies, Kingston, Jamaica. RESULTS: Height increment between 3 and 9 years correlated positively with total haemoglobin at age 7 years in boys but not girls. Attained height and weight at 7 years correlated positively with haemoglobin and fetal haemoglobin in boys but not girls. Only the correlation between haemoglobin and weight showed a significant gender difference. Partial correlation analysis suggested that the effect of haemoglobin was accounted for by the effect of fetal haemoglobin and further analysis indicated that height correlated with F reticulocyte count (a measure of fetal haemoglobin production) in both sexes but not with the ratio of F cells to F reticulocytes (a measure of F cell enrichment). Growth was not significantly related to mean red cell volume, proportional reticulocyte count, alpha thalassaemia, socioeconomic status, or morbidity. CONCLUSION: A high concentration of fetal haemoglobin in boys with SS disease is associated with greater linear growth. It is postulated that in boys, low concentrations of fetal haemoglobin increase haemolysis and hence metabolic requirements for erythropoiesis, putting them at greater risk of poor growth. Differences in the relationship to haemotoloy and growth between boys and girls with SS disease dictate that future analyses of growth take gender into account (AU).x
Assuntos
Humanos , Recém-Nascido , Feminino , Masculino , Anemia Falciforme/sangue , Anemia Falciforme/fisiopatologia , Crescimento/fisiologia , Hemoglobinas/análise , Estatura/fisiologia , Peso Corporal/fisiologia , Estudos de Coortes , Hemoglobina Fetal/análise , Homozigoto , Fatores Sexuais , Classe SocialRESUMO
Five factors have been shown to influence the 20-fold variation of fetal hemoglobin (Hb F) levels in sickle cell anemia (SS): age, sex, the O-globin gene number, á-globin haplotypes, and an X-linked locus that regulates the production of Hb F-containing erythrocytes (F cells), i.e., the F-cell production (FCP) locus. To determine the relative importance of these factors, we studied 257 Jamaican SS subjects from a cohort group identified by newborn screening and from a sib pair study. Linear regression analyses showed that each variable, when analyzed alone, had a significant association with Hb F levels (P < 0.05). Multiple regression analysis, including all variables, showed that the FCP locus is the strongest predictor, accounting for 40 percent of Hb F variation. á-Globin haplotypes, O-globin genes, and age accounted for less than 10 percent of the variation. The association between the á-globin haplotypes and Hb F levels becomes apparent if the influence of the FCP locus is removed by analyzing only individuals with the same FCP phenotype. Thus, the FCP locus is the most important factor identified to date in determining Hb F levels. The variation within each FCP phenotype is modulated by factors associated with the three common á-globin haplotypes and other as yet unidentified factor(s).(AU)
Assuntos
Humanos , Recém-Nascido , Lactente , Pré-Escolar , Criança , Adolescente , Adulto , Hemoglobina Fetal/genética , Anemia Falciforme/genética , Variação Genética , Anemia Falciforme/sangue , Estudos de CoortesRESUMO
In order to investigate the origin(s) of the mutation(s) leading to the beta S-globin gene in North American populations of African ancestory, we analysed DNA polymorphisms in the beta-globin gene cluster in a large number of both beta A- and beta S-globin gene-bearing chromosomes in U.S. and Jamaican Blacks. We found 16 different haplotypes of polymorphic sites associated with 170 beta S-globin gene-bearing chromosomes. The three most common beta S haplotypes, which account for 151/170 of the beta S-globin gene-bearing chromosomes, are only rarely seen in the chromosomes bearing the beta A-globin gene in these populations (6/47). Two observations suggest multiple origins or interallelic gene conversion, or both, of the beta S mutation. First, the mutation is present in all three beta-globin gene frameworks. Second, the beta S haplotypes can be divided into four groups, each of which cannot be derived from any other by less than two crossing-over events. In summary, our observation of the beta S mutation on 16 different halotypes in African populations can be best explained by (i) a number of simple recombination events 5' to the beta-globin gene and (ii) up to four independent mutations and/or interallelic gene conversions. (AU)
Assuntos
Humanos , Alelos , Anemia Falciforme/genética , Conversão Gênica , Genes , Globinas/genética , Hemoglobina Falciforme/genética , Mutação , Polimorfismo Genético , Homozigoto , Jamaica/etnologiaRESUMO
Levels of fetal hemoglobin (HbF) bearing reticulocytes (F reticulocytes) range from 2 percent to 50 percent in patients with sickle cell (SS) anemia. To learn whether any portion of such variation in F cell production is regulated by loci genetically separable from the á- globin gene cluster, percentages of F reticulocytes were compared in 59 sib pairs composed solely of SS members, including 40 pairs from Jamaica and 19 from the United States. We reasoned that differences in F reticulocyte levels might arise (1) from any of several kinds of artifact, (2) via half-sib status, or (3) because one or more genes regulating F cell production segregate separately from ás. We minimized the role of artifact by assay of fresh samples from 84 SS individuals, including both members of 38 sib pairs. In 78 of the 84 subjects, serial values for percent F reticulocytes fell within 99.9 percent confidence limits or were alike by t test (Po .05). This left 32 sib pairs for which F reticulocyte levels in each member were reproducible. When sib-sib comparisons were limited to these 32 pairs, percentages of F reticulocytes were grossly dissimilar within 12 Jamaican and 3 American sibships. Within them, the probability that sibs were alike was always ó .005 and usually ó 10 to the 4th power. We next minimized the contribution of half-sibs among Jamaicans by a combination of paternity testing and sib-sib comparison of á-globin region DNA restriction fragment length polymorphisms, especially among discordant pairs. We thereafter concluded that at least seven to eight Jamaican pairs were composed of reproducibly discordant full sibs. There is thus little doubt that there are genes regulating between-patient differences in F cell production that are separate from the á-globin gene cluster. Still unanswered is (1) whether or not these genes are actually linked to á to the s power, (2) why F reticulocyte levels in Americans tend to be lower than in Jamaicans, and (3) whether or not differences in F cell production among SS patients are regulated by several major loci or by only one (AU)