The beta thalassaemia trait in Jamaica

The objective of this study was to review the prevalence and features of the beta thalassaemia trait in Jamaican populations. Screening of 221,306 newborns over the last 46 years has given an indication of the distribution and prevalence of beta thalassaemia genes, and screening of 16,612 senior school students in Manchester parish, central Jamaica, has provided their haematological features. The prevalence of the beta thalassaemia trait predicted from double heterozygotes was 0.8% of 100,000 babies in Kingston, 0.9% of 121,306 newborns in southwest Jamaica, and 0.9% of school students in Manchester. Mild beta+ thalassaemia variants (-88 C>T, -29 A>G, -90 C>T, polyA T>C) accounted for 75% of Kingston newborns, 76% of newborns in southwest Jamaica, and 89% of Manchester students. Severe beta+ thalassaemia variants were uncommon. Betao thalassaemia variants occurred in 43 patients and resulted from 11 different variants of which the IVSII-849 A>G accounted for 25 (58%) subjects. Red cell indices in IVSII-781 C>G did not differ significantly from HbAA, and this is probably a harmless polymorphism rather than a form of beta+ thalassaemia; the removal of 6 cases in school screening had a minimal effect on the frequency of the beta thalassaemia trait. Red cell indices in the beta+ and betao thalassaemia traits followed established patterns, although both were associated with increased HbF levels. The benign nature of beta+ thalassaemia genes in Jamaica means that cases of sickle cell-beta+ thalassaemia are likely to be overlooked, and important clinical questions such as the role of pneumococcal prophylaxis remain to be answered.

The haematology of Jamaicans: red cell indices in HbAA, HbAS, HbAC, and HbA-HPFH genotypes

Based in the parish of Manchester in central Jamaica, the Manchester Project offered free detection of haemoglobin genotype to senior classes in 15 secondary schools between 2008 and 2013. Restricting the database to 15,103 students aged 15.0-19.9 years provided an opportunity to examine the red cell characteristics of the different haemoglobin genotypes, including normal (HbAA) in 85.0%, the sickle cell trait (HbAS) in 9.7%, HbC trait (HbAC) in 3.5% and hereditary persistence of foetal haemoglobin (HbA-HPFH) in 0.4%. Compared to the normal HbAA phenotype, HbAS had significantly increased mean cell haemoglobin concentration (MCHC), red cell count (RBC), and red cell distribution width (RDW) and decreased mean cell volume (MCV) and mean cell haemoglobin (MCH), these differences being even more marked in HbAC. Compared to HbAA, the HbA-HPFH had significantly increased RDW, but there were no consistent differences in other red cell indices, and there were no significant differences in haematological indices between the two common deletion HPFH variants, HPFH-1 and HPFH-2. Although these changes are unlikely to be clinically significant, they contribute to an understanding of the haematological spectrum of the common haemoglobin genotypes in peoples of African origin.

An international multidisciplinary consensus statement on fasting before procedural sedation in adults and children

The multidisciplinary International Committee for the Advancement of Procedural Sedation presents the first fasting and aspiration prevention recommendations specific to procedural sedation, based on an extensive review of the literature. These were developed using Delphi methodology and assessment of the robustness of the available evidence. The literature evidence is clear that fasting, as currently practiced, often substantially exceeds recommended time thresholds and has known adverse consequences, for example, irritability, dehydration and hypoglycaemia. Fasting does not guarantee an empty stomach, and there is no observed association between aspiration and compliance with common fasting guidelines. The probability of clinically important aspiration during procedural sedation is negligible. In the post-1984 literature there are no published reports of aspiration-associated mortality in children, no reports of death in healthy adults (ASA physical status 1 or 2) and just nine reported deaths in adults of ASA physical status 3 or above. Current concerns about aspiration are out of proportion to the actual risk. Given the lower observed frequency of aspiration and mortality than during general anaesthesia, and the theoretical basis for assuming a lesser risk, fasting strategies in procedural sedation can reasonably be less restrictive. We present a consensus-derived algorithm in which each patient is first risk-stratified during their pre-sedation assessment, using evidence-based factors relating to patient characteristics, comorbidities, the nature of the procedure and the nature of the anticipated sedation technique. Graded fasting precautions for liquids and solids are then recommended for elective procedures based upon this categorisation of negligible, mild or moderate aspiration risk. This consensus statement can serve as a resource to practitioners and policymakers who perform and oversee procedural sedation in patients of all ages, worldwide.

Paediatric emergence delirium: a comprehensive review and interpretation of the literature

There remain unanswered questions and implications related to emergence delirium in children. Although we know that there are some predisposing factors to emergence delirium, we still are unable to predict accurately those who are at greatest risk. Emergence delirium should be considered as a ‘vital sign’, which should be followed and documented in every child in the postanaesthesia recovery period. Standardized screening tools should be adopted for paediatric emergence delirium.

Pulmonary aspiration during procedural sedation: a comprehensive systematic review

Background

Although pulmonary aspiration complicating operative general anaesthesia has been extensively studied, little is known regarding aspiration during procedural sedation.

Methods

We performed a comprehensive, systematic review to identify and catalogue published instances of aspiration involving procedural sedation in patients of all ages. We sought to report descriptively the circumstances, nature, and outcomes of these events.

Results

Of 1249 records identified by our search, we found 35 articles describing one or more occurrences of pulmonary aspiration during procedural sedation. Of the 292 occurrences during gastrointestinal endoscopy, there were eight deaths. Of the 34 unique occurrences for procedures other than endoscopy, there was a single death in a moribund patient, full recovery in 31, and unknown recovery status in two. We found no occurrences of aspiration in non-fasted patients receiving procedures other than endoscopy.

Conclusions

This first systematic review of pulmonary aspiration during procedural sedation identified few occurrences outside of gastrointestinal endoscopy, with full recovery typical. Although diligent caution remains warranted, our data indicate that aspiration during procedural sedation appears rare, idiosyncratic, and typically benign.

Feasibility of measuring memory response to increasing dexmedetomidine sedation in children

BACKGROUND

The memory effect of dexmedetomidine has not been prospectively evaluated in children. We evaluated the feasibility of measuring memory and sedation responses in children during dexmedetomidine sedation for non-painful radiological imaging studies. Secondarily, we quantified changes in memory in relation to the onset of sedation.

METHODS

A 10 min bolus of dexmedetomidine (2 mcg kg^-1) was given to children as they named simple line drawings every five s. The absence of sedation was identified as any verbal response, regardless of correctness. After recovery, recognition memory was tested with correct Yes/No recognitions (50% novel pictures) and was matched to sedation responses during the bolus period (subsequent memory paradigm).

RESULTS

Of 64 accruals, 30 children (mean [SD]6.1 (1.2) yr, eight male) received dexmedetomidine and completed all study tasks. Individual responses were able to be modelled successfully in the 30 children completing all the study tasks, demonstrating feasibility of this approach. Children had 50% probability of verbal response at five min 40 s after infusion start, whereas 50% probability of subsequent recognition memory occurred sooner at four min five s.

CONCLUSIONS

Quantifying memory and sedation effects during dexmedetomidine infusion in verbal children was possible and demonstrated that memory function was present until shortly before verbal unresponsiveness occurred. This is the first study to investigate the effect of dexmedetomidine on memory in children.

CLINICAL TRIAL REGISTRATION

NCT 02354378.

Voluntary premarital screening to prevent sickle cell disease in Jamaica: does it work?

To determine whether identifying haemoglobin genotype, and providing education and counselling to senior school students will influence their choice of partner and reduce the frequency of births with sickle cell disease. The Manchester Project provided free voluntary blood tests to determine haemoglobin genotype to the fifth and sixth forms (grades 11-13), median age of 16.7 years, of all 15 secondary schools in the parish of Manchester in south central Jamaica. A total of 16,636 students complied, and counselling was offered to carriers of abnormal genes over 6 years (2008-2013). The genotypes of their offspring were determined by newborn screening of 66,892 deliveries in 12 regional hospitals over 8 years (2008-2015). The study focused on the genotypes of live deliveries to female students with the four most common haemoglobin genotypes: 7905 with an AA genotype, 898 with the sickle cell trait, 326 with the HbC trait and 78 with the beta thalassaemia trait. A total of 2442 live deliveries were identified by the end of 2015 in mothers screened at school. Eleven babies had clinically significant genotypes, and the prevalence of SS and SC disease did not differ from that predicted by random mating. First pregnancy was not delayed in AS or AC mothers. There was no evidence that knowledge of maternal haemoglobin genotype influenced choice of partner. On an interview, mothers of affected babies correctly recalled their genotype, but either did not discuss this with their partners or the latter refused to be tested. Subjects delaying child bearing for tertiary education would be largely excluded from the present study of first pregnancies and may make greater use of this information. Future options are a greater role for prenatal diagnosis.

Newborn screening for sickle cell disease in Jamaica: logistics and experience with umbilical cord samples

The study aims to describe the logistics and results of a programme for newborn screening for sickle cell disease based on samples from the umbilical cord. Samples were dried on Guthrie cards and analysed by high pressure liquid chromatography. All suspected clinically significant abnormal genotypes were confirmed by age 4-6 weeks with family studies and then recruited to local sickle cell clinics. The programme has screened 66,833 samples with the sickle cell trait in 9.8 % and the HbC trait in 3.8 %. Sickle cell syndromes occurred in 407 babies (204 SS, 148 SC, 35 Sbeta⁺ thalassaemia, 6 Sbeta^o thalassaemia, 6 sickle cell-variants, 8 sickle cell-hereditary persistence of fetal haemoglobin) and HbC syndromes in 42 (22 CC, 14 Cbeta⁺ thalassaemia, 1 Cbeta^o thalassaemia, 5 HbC- hereditary persistence of fetal haemoglobin). Focusing on the year 2015, screening was performed in 15,408, compliance with sample collection was 98.1 %, and maternal contamination occurred in 335 (2.6 %) but in only 0.05 % did diagnostic confusion require patient recall and further tests. This model of newborn screening for sickle cell disease is accurate, robust and economic. It is hoped that it may be helpful for other societies with high prevalence of abnormal haemoglobins and limited resources, who are planning to embark on newborn screening for sickle cell disease.

Recent advances and contributions to procedural sedation with considerations for the future

As the demand for sedation services have increased, the delivery of sedation has shifted from the operating room setting to areas distant to the operating room, both within and outside the hospital setting. Sedation delivery is not monopolized by any one specialty, but rather is being delivered by anesthesiologists as well as non-anesthesiologists. As the field of sedation burgeons and multi-specialists enter the realm of meeting the demands, so also have the politics increased. Unfortunately, the choice of sedative agents has not increased in parallel with the demand for sedation. Over the past decade, there has been a paucity of new introductions for procedural sedation. Rather, new formulations of approved agents are being reexamined. The safe, efficient and predictable delivery of sedation remains at the forefront of discussion and review worldwide. This review will explore the recent, significant and noteworthy contributions to the field of sedation.

Sickle haemoglobin and haemoglobin Stanleyville II: possible confusion with sickle cell-haemoglobin C disease

OBJECTIVES

To bring to the attention of East African practitioners, the characteristics of Hb Stanleyville II, its interaction with HbS, and the resemblance of the double heterozygote to sickle cell-haemoglobin C (SC) disease.

DATA SOURCES

A prospective study of 100 patients with Sickle Cell (SS) disease in the steady state attending the sickle cell Clinic at Mulago Hospital, Kampala, Uganda.

STUDY SELECTION

Out of 100 patients with SS disease, two were also heterozygous for an alpha chain variant identified as Hb Stanleyville II.

CONCLUSIONS

In association with HbS, Hb Stanleyville II produces a hybrid haemoglobin band which on alkaline haemoglobin electrophoresis, travels in the position of HbC. Such cases may cause confusion with sickle cell-haemoglobin C (SC) disease. The index cases in both families had associated alpha thalassaemia but from this small group, no conclusions may be drawn on the haematological or clinical significance of the interaction of Hb Stanleyville II with SS disease.

Accuracy of capnography with a 30 foot nasal cannula for monitoring respiratory rate and end-tidal CO2 in children

We tested the accuracy of a low flow (50 cc/min) sidestream capnography system equipped with an experimental 30-foot nasal cannula to monitor ventilatory status in children. End-tidal CO2 and respiratory rate, both at room air and in the presence of supplemental oxygen, were recorded simultaneously from the experimental 30-foot nasal cannula and the standard, FDA approved, 10-foot nasal cannula. The 30-foot nasal cannula was as accurate as the 10-foot nasal cannula in measuring respiratory rate and end-tidal CO2 in children. When supplemental oxygen was delivered by face-mask, there was no dilutional effect on the respiratory rate or end-tidal CO2 recorded with either the 10-foot or 30-foot nasal cannulas in place.

Coagulation abnormalities in pediatric and adult patients after sclerotherapy or embolization of vascular anomalies

OBJECTIVE

The purpose of our study was to examine the coagulation status in patients with vascular anomalies who had undergone sclerotherapy or embolization.

SUBJECTS AND METHODS

Ours was a prospective pilot study of 29 patients who had undergone sclerotherapy or embolization of large vascular anomalies. Fibrinogen, platelet, and d-dimer levels and prothrombin time were obtained before, immediately after, and on the day after the procedure.

RESULTS

Five patients with venous malformations had positive d-dimer levels before the procedure. A subgroup analysis revealed a relationship between the type of agent used and the change in coagulation status. Specifically, a positive relationship was found between the use of dehydrated alcohol or sodium tetradecyl sulfate and a disruption in coagulation profiles as evidenced by a decrease in platelets and fibrinogen, an increase in prothrombin time, and a conversion from negative to positive d-dimers. In contrast, sclerotherapy or embolization with cyanoacrylic, polyvinyl alcohol foam particles, or platinum microcoils was not associated with coagulation disturbances.

CONCLUSION

The coagulation disturbances that occur in response to dehydrated alcohol or sodium tetradecyl sulfate sclerotherapy or embolization could compromise the patient's clotting ability. Patients who receive dehydrated alcohol or sodium tetradecyl sulfate during a preoperative sclerotherapy or embolization may experience coagulation disturbances that could increase the risk of bleeding, thrombosis, or hematoma. This patient population may benefit from the use of glue, foam, or coils as a substitute for dehydrated alcohol or sodium tetradecyl sulfate.

Sedatives used in pediatric imaging: comparison of IV pentobarbital with IV pentobarbital with midazolam added

OBJECTIVE

This study was designed to evaluate safety, efficacy, and success of adding IV midazolam to an established IV pentobarbital protocol for pediatric sedation for radiologic imaging. Outcomes included sedation and discharge times as well as adverse events

SUBJECTS AND METHODS

This prospective study compared two different sedation protocols developed by the radiology sedation committee and approved by the hospital sedation committee at our institution. Patients in the pentobarbital group received IV pentobarbital alone, and patients in the pentobarbital--midazolam group received a combination of IV pentobarbital and midazolam. A total of 1070 infants and children were enrolled, and sedation data were entered into a computer database and reviewed at bimonthly radiology sedation committee meetings for safety, efficacy, efficiency, failed sedations, and adverse outcomes.

RESULTS

Mean age distribution, sex, American Society of Anesthesiologists physical status classification, fasting status, weight, and types of examinations were similarly distributed between the two study groups. Analysis of variance indicated longer times were required to sedate and to discharge patients who had received pentobarbital--midazolam (p < 0.001 for both times), even after adjusting for differences in the patients' ages and weights. The pentobarbital--midazolam group required more time to be successfully sedated and more time to discharge from the recovery room. The rates of adverse events and failed sedations were similar for both groups.

CONCLUSION

Midazolam does not have a beneficial effect on pentobarbital sedation and has no effect on the rate of adverse events. The prolonged time needed both to sedate and to discharge (timed from the initial dose of sedation) pediatric patients who have received midazolam should discourage physicians from combining it with pentobarbital for pediatric sedation.

National Public Health Performance Standards: workforce development and agency effectiveness in Florida

The Florida Department of Health (FDOH) was the first state to pilot test both the Centers for Disease Control and Prevention (CDC) state agency and local Public Health System Performance Standards. The standards were found to be complementary and supportive of the FDOH quality performance improvement system, which had been in place for a decade, and the new Quality Management initiative. The pilot test found uneven performance across the state's county health departments and identified several areas, especially workforce development, that required additional efforts. The FDOH, in collaboration with the Center for Leadership in Public Health Practice at the College of Public Health in the University of South Florida, have collaborated and will continue to collaborate to design and deliver training in critical workforce development areas.

Perioperative considerations in a hypothyroid infant with hepatic haemangioma

Hepatic haemangiomas in infants are rare. An infant with both a hepatic haemangioma and a severe hypothyroid condition, unresponsive to conventional thyroxine therapy, will be described. This case presented here is the perioperative management of a critically ill infant who had myocardial depression secondary to hypothyroidism and a hepatic haemangioma that required embolization. To our knowledge, this is the first published report describing intravenous triiodothyronine as a therapeutic modality to stabilize a hypothyroid infant prior to undergoing a general anaesthetic.

Serum ethanol levels in children and adults after ethanol embolization or sclerotherapy for vascular anomalies

PURPOSE

To evaluate the serum ethanol level in children and adults after ethanol embolization or sclerotherapy for vascular anomalies.

MATERIALS AND METHODS

Serum ethanol level was evaluated in 71 patients with vascular anomalies who underwent ethanol embolization, sclerotherapy, or both. Blood used to determine serum ethanol level was drawn at the end of each procedure.

RESULTS

The relationship between serum ethanol level and amount of ethanol administered was statistically significant. Results of stepwise linear regression analysis showed that the amount of ethanol administered (P <.001) and type of malformation (P =.02) were multivariate predictors of serum ethanol level. Results of logistic regression analysis revealed that the only uni- or multivariate predictor of legal intoxication was the amount of ethanol administered (P =.018). Five patients fulfilled the criteria for legal intoxication, and the mean amount of ethanol administered to these patients was 0.87 mL per kilogram of body weight +/- 0.18 (SD) (range, 0.55-0.99 mL/kg).

CONCLUSION

The volume of ethanol administered is the most reliable predictor of serum ethanol level and legal intoxication. Patients who receive up to 1.0 mL/kg ethanol during embolization or sclerotherapeutic procedures may have elevated serum ethanol levels that could put them at risk of respiratory depression, cardiac arrhythmias, seizures, rhabdomyolysis, and hypoglycemia.

Gaining strategic advantages through partnerships with public health departments

Public health officials have advocated in public health and public policy journals for collaboration with private sector health care organizations for nearly a decade. There has been little written in the management literature on this topic, however. There are several important areas in which public health departments have expertise that could be valuable to private sector health care organizations, including health maintenance organizations (HMOs). These include the delivery of services in some geographic areas and to some special populations, provision of preventive and health promotion services to HMO members, performance of epidemiology services, assistance in accreditation, and repair of the damaged image of HMOs. HMOs and local health departments in many parts of the country are already entering into contracts for these purposes. Such partnerships between HMOs and local health departments can improve the health of the members of HMO plans and contribute to improving the health of the community.

Sedation for pediatric radiological procedures: analysis of potential causes of sedation failure and paradoxical reactions

BACKGROUND

Sedation for diagnostic imaging and interventional radiologic procedures in pediatrics has greatly increased over the past decade. With appropriate patient selection and monitoring, serious adverse effects are infrequent, but failure to sedate and paradoxical reactions do occur.

OBJECTIVE

The purpose of this study was to determine, among patients undergoing sedation for radiologic procedures, the incidence of sedation failure and paradoxical reaction to pentobarbital and to identify potentially correctable causes.

MATERIALS AND METHODS

Records of 1665 patients who were sedated in the radiology department from 1 November 1997 to 1 July 1998 were reviewed. Patients failing sedation or experiencing paradoxical reaction were compared with respect to sex, age group, diagnosis, scan type, time of day, NPO status, use of IV contrast and type of sedation agent using the Fisher exact test, Pearson chi-square, analysis of variance (ANOVA), the Student t-test, and logistic regression.

RESULTS

Data analysis revealed a sedation failure rate of 1 % and paradoxical reaction rate of 1.2 %. Stepwise multiple logistic regression revealed that the only significant independent multivariate predictor of failure was the need for the administration of a combination of pentobarbital, fentanyl, and midazolam IV.

CONCLUSION

The low rate of sedation failure and paradoxical reactions to pentobarbital was near optimal and probably cannot be improved with the currently available sedatives.

Assurance opportunities for local health departments

CONTEXT

Widespread changes in health care in the United States, especially the growth in the number and membership of health maintenance organizations (HMOs), provide increasing opportunities for collaboration, especially through contracts, between local health departments (LHDs) and HMOs to achieve public health goals.

OBJECTIVES

(1) To identify, through a review of the literature, the areas in which HMOs and LHDs can collaborate to their mutual benefit and (2) for the leadership of an LHD in Florida to engage HMOs in its county in Florida in collaboration.

DESIGN

University faculty reviewed the relevant literature; the Director of Medical Services for the Duval County Health Department developed the relationships with Duval County HMOs.

SETTING

The setting for the study was Duval County.

PARTICIPANTS

The participants in the study included faculty from the College of Public Health at the University of South Florida, State and county public health officials, and representatives of 10 HMOs.

MAIN OUTCOME MEASURES

The main outcome measures were a literature review to identify feasible areas for collaboration and successful collaboration with HMOs in areas of mutual interest.

RESULTS

The director of medical services for the county health department initiated a variety of collaborative activities with 10 HMOs. These led to agreements, participation on committees and task forces, provision of services, and improved communication.

CONCLUSIONS

Collaboration between LHDs and HMOs to achieve public health assurance goals is feasible. Other organizations can encourage such collaboration through public and private policies.

Roles and opportunities for local health departments in managed care markets

Managed care organizations (MCOs) are increasing their share of many local markets and are increasingly providing services to newly insured populations and Medicaid eligibles. Local health departments (LHDs) in these markets must determine what strategies they wish to pursue in this new health care environment. Possible roles are identified (from public health services only to a full range of services). LHDs are encouraged to use their strategic advantages to contract with MCOs to serve geographic, socioeconomic, and cultural populations that differ from those that MCOs are accustomed to serve. Accreditation guidelines of the National Committee for Quality Assurance are summarized and their relationship to LHD activities discussed.

Blood rheology and proliferative retinopathy in homozygous sickle cell disease

Some haematological and rheological features were compared in 27 age and sex matched pairs of patients (15 male, 12 female) with homozygous sickle cell (SS) disease with and without proliferative sickle retinopathy (PSR). Significant haematological differences between the groups were a higher haemoglobin and a lower fetal haemoglobin in PSR positive males and a higher MCHC in PSR positive females. The plasma viscosity and characteristics of erythrocyte filterability did not differ between those with and those without PSR, although PSR positive males had a significantly higher whole blood viscosity when measured at high shear and at the patient's own packed cell volume.

Blood rheology and proliferative retinopathy in sickle cell-haemoglobin C disease

Haematological and rheological (plasma and serum viscosity, whole blood viscosity, and erythrocyte filterability) factors were studied in 31 age-sex matched pairs of patients with sickle cell haemoglobin C disease with and without proliferative sickle retinopathy (PSR). Patients with PSR had significantly higher mean cell haemoglobin and lower Hb F levels on average than the matched controls, but the viscosity and erythrocyte filtration indices did not differ between the 2 groups. There was, therefore, no evidence of rheological differences between patients with and without PSR at the time of the study, although transient rheological abnormalities at the time of development of PSR could not be excluded. Prospective longitudinal studies of rheology before, during, and after the development of PSR would be necessary to detect such changes.

Effect of alpha thalassaemia on the rheology of homozygous sickle cell disease

A study of rheological determinants (plasma viscosity, whole-blood viscosity, and erythrocyte deformability) was made in 24 matched pairs of patients with homozygous sickle cell disease, with and without homozygous alpha-thalassaemia 2. Patients with coexisting alpha-thalassaemia showed a significant increase in erythrocyte deformability measured as filtration of washed erythrocytes through 5 micron diameter pores and also as viscosity of whole blood at high shear rate (230s-1) and standard haematocrit (0.45). This rheological advantage may explain the beneficial effect of alpha-thalassaemia 2 on haematological parameters and clinical events in homozygous sickle cell disease.

Post-natal decline of fetal haemoglobin in homozygous sickle cell disease: relationship to parenteral Hb F levels

The decline of fetal haemoglobin (Hb F) from birth to 6 years has been compared in a cohort of 266 Jamaican children with homozygous sickle cel (SS) disease and in 243 matched controls with a normal haemoglobin (AA) genotype. Hb F levels were significantly higher in the SS cases from 1 month onward but, unlike the normal controls, no sex difference was apparent. The Hb F levels in SS disease were significantly correlated with parental Hb F levels, suggesting that genetic factors regulating adult Hb F levels are active at earlier stages in development. Furthermore, some of these genetic determinants of Hb F production may be linked to the beta-like globin gene complex and be in linkage disequilibrium with the beta s allele.

The interaction of alpha-thalassemia and homozygous sickle-cell disease

Patients with homozygous sickle-cell disease may be homozygous for alpha-thalassemia 2 (alpha-/alpha-), may be heterozygous for alpha-thalassemia 2 (alpha-/alpha alpha), or may have a normal alpha-globin-gene complement (alpha alpha/alpha alpha). We compared the clinical and hematologic features of 44 patients who had sickle-cell disease and homozygous alpha-thalassemia 2 with those of controls with the two hematologic conditions. The patients with homozygous alpha-thalassemia 2 had significantly higher red-cell counts and levels of hemoglobin and hemoglobin A2, as well as significantly lower hemoglobin F, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, mean corpuscular volume, reticulocyte counts, irreversibly-sickled cell counts, and serum total bilirubin levels, than those with a normal alpha-globin-gene complement. Heterozygotes (alpha-/alpha alpha) had intermediate values. In the group with homozygous alpha-thalassemia 2, fewer patients had episodes of acute chest syndrome and chronic leg ulceration and more patients had splenomegaly, as compared with patients in other two subgroups. These data confirm previous suggestions that alpha-thalassemia inhibits in vivo sickling in homozygous sickle-cell disease and may be an important genetic determinant of its hematologic severity.

Sickle cell-Hb Lepore Boston syndrome. Uncommon differential diagnosis to homozygous sickle cell disease

Two siblings assumed on the basis of clinical and hematological evidence to have homozygous sickle cell (SS) disease were found to have a mother without sickle hemoglobin. Subsequent investigation and hemoglobin structural studies indicated the diagnosis to be sickle cell-Hb Lepore Boston syndrome. This syndrome generally manifests clinically significant sickle cell disease, and this genotype should be borne in mind in apparent SS disease where a parent without sickle hemoglobin in discovered.

Negro alpha-thalassaemia: genetic studies in homozygous sickle cell disease

Interaction with the alpha-thalassaemia phenotypes lowers the proportion of Hb S in the sickle cell trait and influences the mean cell volume and proportional Hb A2 in homozygous sickle cell (SS) disease. By assigning somewhat arbitrary values to the alpha-thalassaemia 1 and alpha-thalassaemia 2 phenotypes in these conditions, it has been possible to investigate the patterns of inheritance of alpha-thalassaemia in black populations. The results strongly support the hypothesis that the alpha-thalassaemia 1 phenotype represents homozygosity for alpha-thalassaemia 2.

The determinants of irreversibly sickled cells in homozygous sickle cell disease

The relationship between the irreversibly sickled cell (ISC) count and other haematological parameters has been investigated. Positive correlations occurred with the MCH, MCHC, and with two expressions of intracellular Hb S content. Since the ISC has a high MCHC, the positive correlations with MCHC and with factors derived from the MCHC may be difficult to evaluate. Negative correlations occurred with total haemoglobin and Hb F. The MCHC was found to affect the relationship between HbF and ISC count, a low MCHC being associated with, and probably determining, lower ISC counts at any level of Hb F. It is proposed that a low MCHC may inhibit ISC formation and the practical implications of this are discussed.

The development of haemoglobin A2 in normal negro infants and in sickle cell disease

The development of haemoglobin A2 levels from birth to 3 years has been compared in normal, beta-thalassaemia trait, sickle cell (SS) disease, and S-beta-thalassaemia genotypes. Hb A2 levels were almost identical in normals and in children with SS disease at 1, 2 and 3 years. The most rapid increases in Hb A2 levels occurred before 6 months but levels were still rising at the end of the third year. Sickle cell-beta+ thalassaemia could be differentiated from SS disease by the higher Hb A2 levels between 6 months and 1 year. Insufficient data were available on S-beta o thalassaemia but since Hb A2 levels in this condition are generally higher than those in S-beta+ thalassaemia, differentiation from SS disease may may also be possible from the age of 6 months.