Relatively benign sickle-cell anaemia in 60 patients aged over 30 in the West Indies

Phenotypic variation in sickle cell disease: the role of beta globin haplotype, alpha thalassaemia and fetal haemoglobin in HbSS

INTRODUCTION

The haematological and clinical feature vary markedly between the different genotypes of sickle cell disease. Even within the single genotype of homozygous sickle cell disease (HbSS), there is marked variability which is presumed to result from interacting genetic and environmental factors.

AREAS COVERED

The classification of the different genotypes of sickle cell disease with approximate prevalence at birth in different communities and some of the major clinical and haematological differences. This assessment includes three potential genetic factors influencing haematology and clinical outcome in HbSS, the beta globin haplotype, alpha thalassaemia and persistence of fetal haemoglobin (HbF).

EXPERT OPINION

The author is a clinician with experience of sickle cell disease primarily in Jamaica but also in Greece, Uganda, Saudi Arabia and India. It is therefore necessarily an account of clinical data and does not address current debates on molecular mechanisms. Most data derive from Jamaica where efforts have been made to reduce any symptomatic bias by long term follow-up of patients all over the island and further reduced by a cohort study based on newborn screening which has been in operation for over 48 years.

Male sickle cell patients, compensated transpubertal hypogonadism and normal final growth

OBJECTIVE

Investigate the gonadal hormonal function in sickle cell individuals.

CONTEXT

Sickle cell disease (SCD) is associated with delayed physical and sexual development, and it has been related to both primary testicular failure and hypothalamo-pituitary-gonadal axis abnormalities.

DESIGN

The study of the pituitary gonadotrophin reserve was done evaluating the hormonal levels before and after stimulation by gonadoliberin.

PATIENTS

Male patients with homozygous SCD (18-39 years, median = 29.5 years).

MEASUREMENTS

Gonadal function was evaluated through clinical parameters and the hormonal quantification.

RESULTS

Although low body weight and other clinical signs of undernutrition such as clinical hypoandrogenism and the extreme retardation of puberty were seen in these patients, final stature and hormonal testicular reserve to hCG stimulation were proved to be normal according to our previous data. In the present investigation, the basal luteotropic gonadotropin (LH), follicle-stimulating hormone (FSH) and testosterone (T) levels were similar between the patients and controls. Prostate-specific antigen (PSA) levels-used as a biochemical marker of androgenicity, mainly in puberty-were lower in the patients than in the controls and were only correlated with T. A subtle abnormality in the pituitary responsivity to gonadotropin-releasing hormone (GnRH) was disclosed, with a higher response to LH 60 minutes after stimulation in patients than in controls.

CONCLUSIONS

These data, in addition to both the clinical and biochemical signs of hypoandrogenism associated with normal to elevated T levels strongly suggest a peripheral origin of hypogonadism, which is probably due to androgen resistance in the patients with SCD.

Alpha thalassemia among sickle cell anaemia patients in Kampala, Uganda

BACKGROUND

Sickle cell anaemia is prevalent in sub Saharan Africa. While α+-thalassaemia is known to modulate sickle cell anaemia, its magnitude and significance in Uganda have hitherto not been described.

OBJECTIVES

To determine the prevalence of α+thalassaemia among sickle cell anaemia patients in Mulago Hospital and to describe the clinical and laboratory findings in these patients.

METHODS

A cross sectional study was carried out on patients with sickle cell anaemia in Kampala. Dried blood spots were used to analyze for the deletional α+ thalassaemia using multiplex polymerase chain reaction.

RESULTS

Of the 142 patients with sickle cell anaemia, 110 (77.5%) had the αα+thalassaemia deletion. The gene frequency of (-α) was 0.425. Ninety one percent (100/110) of those with α+thalassaemia were heterozygous (αα/α-). Amongst the patients older than 60 months, 15 (83.3%) of those without αα+thalassaemia had significant hepatomegaly of greater than 4 cm compared to 36 (45.6%) of those with α+thalassaemia (p=0.003).

CONCLUSION

The gene frequency of (-α) of 0.425 noted in this study is higher than that reported from many places in Africa. Concurrent alpha thalassemia might be a protective trait against significant hepatomegaly in sickle cell anaemia patients more than 60 months of age at Mulago hospital.

Clinical Factors Associated with Morbidity and Mortality in Patients Admitted with Sickle Cell Disease

OBJECTIVE

To determine the clinical factors associated with the length of hospitalization and mortality in patients with sickle cell disease (SCD).

METHODS

All patients with SCD admitted to the medical wards of the University Hospital of the West Indies, Jamaica, over a five-year period, January 1 to December 31, 2010, were reviewed. Data were extracted from hospital charts and comprised demographic and clinical information, investigations, interventions, duration of stay, pathological data and outcomes.

RESULTS

There were 105 patients reviewed; 84% were genotype Hb SS. Females accounted for 59% and males 41%. Overall mean age was 32.5 years (SD 13.7, range 12-66 years). The mean length of hospitalization was 10.2 days (SD 10.9, range 1-84 days). The main admission diagnoses were painful crisis, acute chest syndrome, severe anaemia, sepsis, hepatic sequestration, congestive cardiac failure and renal failure. The mean value for the following laboratory investigations were: haemoglobin 7.7 g/dL (SD 2.8), total white blood cell count 21.7 x 109/L (SD 14.2), platelet count 320 x 109/L (SD 191.9), blood urea 9.8 mmol/L (SD 11.9) and serum creatinine 198 umol/L (SD 267.9). Medical interventions included: blood transfusions in 20.9%, 55% received antibiotics and 74% received narcotic analgesia. There were 40 deaths with four autopsies done. The mortality rate for SCD was 38%. There were 189 repeat SCD admissions.

CONCLUSION

Sickle cell disease still carries a high morbidity and mortality in patients admitted to hospital. Recurrent admissions are a concern, as they impact on patient's morbidity and quality of life.

Impaired pubertal development and testicular hormone function in males with sickle cell anemia

Changes in weight/height ratio, delayed sexual maturation, hypogonadism and impaired fertility have been demonstrated in sickle cell disease (SCD). This study aimed to evaluate the clinical and laboratory views of the Leydig cells function after stimulation with hCG in adults with sickle cell disease. We studied 15 patients with SCD (18 to 40 years; median=27 years old), fourteen homozygous S, and one with SC disease. The control group, composed by adult males, was divided into two groups: I - 10 relatives (18-39 years, median=26 years) with the same socioeconomic level of the patients, and II - 9 normal individuals (23-28, median=31 years) randomly chosen. Clinically it was observed a slight degree of malnutrition, important puberty delay, rarefaction of chest, underarm and pubic hair, and important reduction of the testis and penis size, featuring a mild hypogonadism in patients with SCD. The hormonal level assessment of testosterone at baseline and at 24, 48 and 72 h after hCG stimulation showed no significant differences between the groups studied. We can presume that adult men with SCD showed clinical hypoandrogenism with normal testicular hormonal function, a fact inconsistent with the hypothesis of primary hypogonadism.

Polymorphism in the HMOX1 gene is associated with high levels of fetal hemoglobin in Brazilian patients with sickle cell anemia

The aim of this study was to investigate the association between three polymorphisms involved in the oxidative stress pathway and fetal hemoglobin (Hb F) levels in patients with sickle cell anemia in a Brazilian population. One hundred and seven patients with sickle cell anemia were recruited for genomic DNA extraction. The levels of Hb F, sex and age were evaluated. Three polymorphisms, rs4673:T>C and rs9932581:G>A in the CYBA gene and rs2071746:A>T in the HMOX1 gene, were identified through direct sequencing. Hb F levels were not associated with sex, age, or the polymorphisms rs4673:T>C and rs9932581:G>A. However, the TT genotype of the rs2071746:A>T polymorphism was associated with increased levels of Hb F (p value = 0.0131). We observed an association between the TT genotype of the rs2071746:A>T polymorphism, present in the HMOX1 gene, and increased levels of Hb F, indicating the presence of a new marker related to Hb F levels in sickle cell anemia patients.

Genetic modifiers of sickle cell disease

Sickle cell anemia is associated with unusual clinical heterogeneity for a Mendelian disorder. Fetal hemoglobin concentration and coincident α thalassemia, both which directly affect the sickle erythrocyte, are the major modulators of the phenotype of disease. Understanding the genetics underlying the heritable subphenotypes of sickle cell anemia would be prognostically useful, could inform personalized therapeutics, and might help the discovery of new "druggable" pathophysiologic targets. Genotype-phenotype association studies have been used to identify novel genetic modifiers. In the future, whole genome sequencing with its promise of discovering hitherto unsuspected variants could add to our understanding of the genetic modifiers of this disease.

Sickle cell disease in the United States: looking back and forward at 100 years of progress in management and survival

The past 100 years since James Herrick's first description of sickle cell disease in the United States have been characterized by the gradual development of management strategies. We review the progress in sickle cell disease management in the United States over the past 100 years, with emphasis on the diverse forces surrounding advances in disease management. Mortality and survival data are presented chronologically, with an attempt to highlight improvements in survival associated with specific advancements for pediatric and adult care. Finally, the future course for sickle cell disease management is explored, given the continued work in advancing the field.

Prognostic significance of early vaso-occlusive complications in children with sickle cell anemia

Sickle cell anemia (SS) is highly phenotypically variable, and early predictors of outcome could guide clinical care. To determine whether early vaso-occlusive complications predicted subsequent adverse outcomes in the Dallas Newborn Cohort, we studied all members with SS or sickle-beta0-thalassemia who presented in their first year of life and had 5 years or more of follow-up. We defined 3 potential early predictors: hospitalizations in the first 3 years of life for (1) painful events other than dactylitis, (2) dactylitis, and (3) acute chest syndrome (ACS). We studied the associations of these predictors with the following late adverse outcomes (occurring after the third birthday): death, first overt stroke, use of disease-modifying therapy, and hospitalizations for pain events and ACS. None of the early events predicted death or stroke. Early pain and ACS both predicted a modest, temporary increase in the number of later painful episodes, but early ACS strongly increased the odds of more frequent ACS throughout childhood. Dactylitis had limited utility as a predictor. Although we still lack a useful prognostic framework for young children with SS, those who experience early ACS might be candidates for higher risk interventions to mitigate or cure their disease.

Risk factors and prediction of outcomes in children and adolescents who have sickle cell anemia

This article discusses risk factors and prediction in children and adolescents who have sickle cell anemia.

Survival estimates for patients with homozygous sickle-cell disease in Jamaica: a clinic-based population study

BACKGROUND

Information about life expectancy of patients with homozygous sickle-cell disease is needed for research and patient counselling. Our aim was to study two Jamaican populations, one clinic-based and one birth cohort and, by careful consideration of data quality and statistical analysis, to identify ways to increase the chances of obtaining valid and generalisable results.

METHODS

We investigated the survival experience of 3301 patients with homozygous sickle-cell disease attending the Jamaican sickle-cell clinic between Jan 1, 1987, and Dec 31, 1996. We applied and assessed a simulation technique for incorporating early life mortality using a birth cohort, and analysed the precision of this technique. Kaplan-Meier survival estimates are produced.

FINDINGS

290 of the 3301 patients died. Median survival calculated with the excess mortality rate simulation data was 53 years (95% CI 49.3-57.0) for men and 58.5 (55.1-67.5) for women.

INTERPRETATION

Our simulation technique, with realistic assumptions based on empirical evidence, offers a new estimate of median survival for patients with homozygous sickle-cell disease. We present the precision of these survival estimates, which introduces an important level of uncertainty. The inherent biases of clinically ascertained populations of patients, and the assumptions underlying analysis techniques are crucial features of survival studies in sickle-cell disease, and can modify summary statistics substantially.

Benign clinical course in homozygous sickle cell disease: a search for predictors

AIMS

(1) To estimate the proportion of subjects with homozygous sickle cell disease who have a benign clinical course, and (2) to assess factors that may be predictive of benign disease.

MATERIAL

Subjects (n = 280) were participants in a longitudinal cohort study of sickle cell disease. They were classified as benign or control based on clinical history from birth to age 13 years old. Associations with growth, hematology, and an index of social status were investigated.

RESULTS

Benign disease occurred in 43 (15%) patients. Neither growth nor social status were related to benign disease. There were only two statistically independent associations: alpha thalassemia status and average steady state fetal hemoglobin (HbF). Patients with a normal complement of alpha globin genes were 2.2 (1.0, 4.9) times more likely to have benign disease than those with gene deletion, and were less likely to have frequent painful crises, dactylitis, and bone necrosis. The odds of having benign disease were 1.09 (1.02, 1.17) times higher for each unit increase in HbF, and 44% of subjects with HbF in the top decile (HbF > 13.8%) of the distribution had benign disease. There was no evidence for a threshold effect of high HbF on benign disease.

CONCLUSION

A benign clinical course of sickle cell disease may occur in Jamaica and is associated with a normal alpha globin gene complement, and high levels of HhF. Ability to predict benign disease at birth is limited.

Delayed sexual maturation in sickle cell anaemia patients--observations in one practice

Pubic hair and breast appearance ratings, testicular volumes and age at menarche were determined in 24 sickle cell anaemia patients aged from 8.5 to 27 years between February and September 1994 in the Wesley Guild Hospital, Ilesa, Nigeria. Only three of the six females aged 15 or more years had experienced menarche and this was at the mean (SD) age of 18.8 (4.5) years. Public hair appearance and breast development had commenced in only six and seven, respectively, of the 12 females, and in every case the ratings were significantly low for their ages. Male testicular volume was also low for their age in the six of 12 males who were 13 years of age, and above, and pubic hair had appeared in only two of them, aged 20 and 27 years. The height of all the patients was delayed. It is important to recognize that significant delay in sexual development may accompany sickle cell anaemia and to take appropriate steps in managing and counselling the patients.

Screening for ophthalmic manifestations of sickle cell disease in the United Kingdom

There are marked variations in the manifestations of sickle disease in different populations. The ocular complications of this condition amongst the Afro-Caribbeans living in the United Kingdom have not previously been reported. We present the preliminary results of an ophthalmic screening programme at King's College Hospital, London. One hundred eyes of 50 patients with sickle cell disease were assessed. Full ocular examination was performed including fundus fluorescein angiography. We have looked at the haematological and clinical profile of the patients involved as well as the number of days spent in hospital during the year preceding the eye examination. The incidence of grade II retinopathy was found to be significantly higher than grade I in SC disease. This concurs with the results of the Jamaican screening and confirms that these patients are at higher risk of visual impairment than those with SS disease. Our results also agree with the Jamaican experience which suggest that visual morbidity is mostly due to complications of proliferative sickle retinopathy (PSR). However, the findings in patients without proliferative changes are different; in particular, angioid streaks leading to disciforms are an important cause of visual loss in Jamaica, but were not seen in any of the 98 eyes examined in this study. No correlation was found between the grade of retinopathy and age, sex, systemic complications and various haematological parameters except for the percentage of haemoglobin F, which was significantly higher in patients with grade I (7.6) compared with grade II (4.2) retinopathy (p = 0.0127).

Fetal hemoglobin synthesis in sickle cell anemia: some molecular considerations

An ability to maintain high levels of fetal hemoglobin (Hb F) has been associated with the amelioration of the clinical severity of the sickle cell disease (SS). Clinical efforts to increase the Hb F level of the patients have, however, yielded variable therapeutic response. In an attempt to further elucidate the underlying molecular basis, in vitro Hb F synthesis was studied in erythroid progenitor (BFU-E) cells obtained from SS patients and their heterozygous (AS) relatives with varying genetic backgrounds. This allows us to study the Hb F biosynthesis pattern uncomplicated by the influence of the preferential survival of "F cells" in vivo. The Hb F levels and the relative concentrations of its constituent gamma globin chains, G gamma and A gamma, were assayed using the reversed phase HPLC method. A percentage increase in the fetal hemoglobin content was observed in the lysates of the erythroid progenitor cells relative to the circulating peripheral blood erythrocyte values in SS patients and their AS relatives with different beta S haplotypes reflecting the intrinsic capacity of fetal hemoglobin synthesis in these subjects. No such increase was observed in the patient with the Mor haplotype. Furthermore, the Hb F synthesized in the BFU-E colonies was more of the adult type, as evidenced by the decrease in the percent G gamma level relative to the corresponding peripheral blood values of the subjects in all the haplotype groups studied. The Mor haplotype was again an exception, synthesizing fetal hemoglobin more of the fetal type.

Growth retardation in homozygous sickle cell disease: role of calorie intake and possible gender-related differences

To evaluate the possible role of inadequate food intake in the pathogenesis of the growth retardation of patients with sickle cell anemia, we determined the daily intake of calories and macronutrients and measured several anthropometric indices in 20 patients with sickle cell anemia aged 17-35 years and in 15 of their normal siblings of similar age. Compared to the control groups, the male patients, but not the females, had a significantly lower mean weight, body mass index, midarm circumference, and triceps and subscapular skinfold thicknesses. Also, while the male patients consumed significantly less total calories, proteins, carbohydrates, and fats per day than their control group, no difference was noted between the daily intake of calories or macronutrients in the female patients and their control group. However, when the intake of calories and macronutrients was corrected for body weight, there was no statistically significant difference between the intake of nutrients in the male patients and their control subjects or between the female patients and their control group. These results suggest a sex-related difference in the somatic growth of adolescent and adult patients with sickle cell anemia and also suggest that, although an inadequate food intake may be partly responsible for the impaired somatic growth in sickle cell anemia, other factors are also probably important.

Serum calcium, parathyroid hormone, and vitamin D status in children and young adults with sickle cell disease

The concentrations of serum calcium, parathyroid hormone (PTH), 25 Hydroxyvitamin D (25OHD), and 1,25 Dihydroxyvitamin D (1,25(OH)2D) were determined in 99 Saudi patients with sickle cell disease and in 104 matching healthy controls. Serum calcium and 25OHD were significantly lower in the patients, with 14% and 12% of them had serum calcium and 25OHD concentrations, respectively, below the normal range. PTH was significantly higher in the patients, with 31% having values above the normal range. There was no significant difference between patients and controls in regard to 1,25(OH)2D. There was a significant inverse correlation of 25OHD with PTH and a direct correlation of PTH with 1,25(OH)2D. Dietary intake of calcium and vitamin D was adequate in both patients and controls. The results indicate that sickle cell patients have hypocalcaemic tendency associated with supranormal PTH, and imply impaired intestinal absorption of calcium and vitamin D leading to a disturbed calcium metabolism which might contribute to the skeletal changes seen in sickle cell disease.

Immunological studies in sickle cell disease: comparison of homozygote mild and severe variants

Cellular and humoral immune functions in patients suffering from severe and mild forms of homozygous sickle cell disease (SCD) were compared with those of healthy control subjects. Random neutrophil migration, chemotactic activity, and lymphocyte transformation index were all defective in individuals with severe variants of SCD when compared with individuals with mild disease or healthy controls. In contrast, serum opsonization activity was significantly reduced in both severe and mild variants of SCD. There were no statistical differences between serum immunoglobulin (IgA, IgG, and IgM) or complement C3 levels in any of the three groups. These results demonstrate that even though individuals with the mild variant of SCD possess two S genes, their immune functions are generally normal and in parallel with their clinical and hematological status. The one area of impaired immune function is their defective serum opsonization activity and this may explain their sensitivity to certain infections.

Endoscopic and gastric acid studies in homozygous sickle cell disease and upper abdominal pain

Upper endoscopic and gastric acid output studies were done in 51 patients with homozygous sickle cell (SS) disease and recurrent epigastric pain. Twenty (39%) had abnormalities in the upper gastrointestinal tract including 18 (35%) with peptic ulcers. Mean basal and maximum acid output were similar in patients with and without duodenal ulcer (DU). Because DU in SS disease does not appear to be associated with high acid outputs observed in other populations, it may reflect reduced mucosal resistance, possibly resulting from ischaemia. This hypothesis was supported by the significantly lower fetal haemoglobin level among SS-DU patients.

Nutrition and sickle cell disease

The role of protein and calorie deficiency in sickle cell disease remains poorly defined. While such features as growth retardation, impaired immune function, and delayed menarche do suggest a relationship between sickle cell disease and undernutrition, measurement of more direct nutritional parameters in these patients have yielded mixed results. Anthropometric measurements such as skinfold thickness are subnormal in many but not all reports. Serum protein levels are normal, but low values for serum lipids have been reported. Finally, one small study shows an improvement in both growth parameters and clinical course following caloric supplementation. A variety of micronutrient deficiencies have been suggested in sickle cell disease. Numerous case reports describing an exacerbation of the chronic anemia that was reversed by folic acid therapy led to routine folate supplementation. More recent studies have shown, however, that clinically significant folic acid deficiency occurs only in a small minority of sickle cell patients. Clearly, more work is necessary to define the cost/benefit ratio of routine folic acid supplementation. Pharmacological amounts of vitamin B6 and certain of its derivatives possess in vitro antisickling activities. Nevertheless, a small clinical trial failed to demonstrate any consistent hematologic effects of B6 supplementation. Several reports indicate that vitamin E levels are low in sickle erythrocytes. Since these abnormal red cells both generate excessive oxidation products and are more sensitive to oxidant stress, and because oxidants appear to play a role in ISC formation, vitamin E deficiency could well be linked to ISC formation and hemolysis. Small clinical trials, however, have again failed to produce a clear hematological response in sickle cell anemia. The role of zinc in sickle cell disease has received considerable attention. Though studies are generally small, most do support a relationship between sickle cell disease and zinc deficiency. Etiologic associations between zinc deficiency and such complications of sickle cell disease as poor ulcer healing, growth retardation, delays in sexual development, immune deficiencies, and high ISC counts have all been suggested. Most of these studies need further corroboration. Iron deficiency is now known to be a relatively common occurrence in sickle cell anemia, especially in children and pregnant women. The theoretical benefits of concomitant iron deficiency and sickle cell anemia remain to be proven in a controlled clinical trial.(ABSTRACT TRUNCATED AT 400 WORDS)

Anti-sickling effect of dietary thiocyanate in prophylactic control of sickle cell anemia

As a clinical entity, sickle cell anemia (SCA) is known to be relatively rarer in Africans than in the African-American population of the United States. Paradoxically, sickle cell trait (SCT), the non-anemic, heterozygous condition, is about three times more common among indigenous Africans than in African-Americans. The ratio of SCA to SCT is 1:50 for African-Americans, and less than 1:1,000 for tropical Africans. This etiological disparity is attributed to an anti-sickling agent, thiocyanate, (SCN-) found abundantly in staple African foods, such as the African yam (Dioscorea sp) and cassava (Manihot utilissima). Staple American foods have negligible SCN-concentrations. Nonstaple foods in the American diet, such as carrots, cabbage, and radishes, have SCN- levels far below the African yam and cassava. This finding explains the high incidence of SCA among African-Americans and its rarity in Africans.The author concludes that SCA is a congenital deficiency anemia, ameliorable by prophylactic diets of foods with high SCN- contents. Thus, "thiocyanate deficiency anemia" is nutritionally a more correct clinical status for those born with the homozygous sickle hemoglobin genome. Just as any iron undernourished person can suffer from iron deficiency anemia, sickle hemoglobin homozygotes suffer from "thiocyanate deficiency anemia" when they subsist on SCN-deficient foods. This article reviews the role of dietary SCN- in SCA control.

Non-benign sickle cell anaemia in western Saudi Arabia

Seventy-one Saudi and Yemeni Arabs with sickle cell anaemia from western Saudi Arabia aged between 1 1/2 and 42 years were studied. The mean steady state haemoglobin concentration of 8.1 g/dl was lower than that of 10.7 g/dl reported previously for sickle cell anaemia in eastern Saudi Arabia. The patients were divided into an SSLF group with fetal haemoglobin (HbF) of 10.0% or below (44 patients) and an SSHF group having HbF above 10.0% (27 patients). No significant differences were found in the haemoglobin concentrations, haematological indices and incidences of bone changes of the two groups. SSLF patients were significantly more prone to infections (P less than 0.01), however. Also, there was an overall high incidence of hepatomegaly (69.0%) and splenomegaly (54.9%) and hepatomegaly was significantly more common in the SSLF group (P less than 0.02). Many of the patients, even with HbF levels over 10.0%, did not follow a benign course and suffered from severe anaemia, infections of the respiratory and urinary tracts, bone pains and infarcts, or bossing of the skull. Rarer complications included hepatic crisis, chest syndrome, retinal haemorrhage, epistaxis and hemiplegia. It is therefore apparent that Saudi Arabian sickle cell anaemia, even in patients with raised haemoglobin F levels, may be as clinically severe as in African patients.

Influence of sickle hemoglobinopathies on growth and development

To determine the influence of hemoglobinopathy on growth and development, we examined the height, weight, and sexual maturation of 2115 patients 2 to 25 years old who had homozygous sickle-cell disease (SS), SC disease (SC), sickle beta+ thalassemia (S beta+), or sickle beta O thalassemia (S beta O). Using regression analysis of these cross-sectional data to generate growth and maturation curves for each hemoglobinopathy, we found that the curves for all hemoglobinopathy groups were significantly different from published norms for black subjects (P less than 0.001), and that subjects with SS and S beta O were consistently smaller and less sexually developed than those with SC and S beta+ (P less than 0.001). For both sexes and all hemoglobinopathies, low weight was more pronounced than short height and was most apparent in subjects over the age of seven. The median age of the female subjects who had attained at least Tanner Stage V was 17.3 years for those with SS, 17.2 years for S beta O, 16.0 years for SC, and 16.5 years for S beta+; among male subjects the corresponding values were 17.6, 18.8, 16.6, and 16.6 years. Discriminant analysis of menarche status, weight, age, and hemoglobinopathy revealed that the influences of age and weight on menarche were similar regardless of hemoglobinopathy. This relationship suggests a constitutional rather than a primary endocrinologic cause of sexual immaturity in patients with hemoglobinopathies.

Heterogeneity of sickle-cell anemia based on a profile of hematological variables

Factors that influence the heterogeneity of the disease expression of sickle-cell anemia are not well understood. This study examines the ability of a profile of six hematological variables (HB, HCT, RBC, %Hb F, MCV, and %HBA2) to predict the severity of disease measured on 225 patients ranging from 0.2 to 18 years of age. Four subgroups of patients were identified separately in each sex using cluster analysis techniques. In each sex, mean hemoglobin concentration and percent Hb F increased across the four clusters from 7 to 10 gm/dl and from 7% to 16%, respectively. Mean cell volumes were approximately 90, 80, 90, and 75 in groups 1, 2, 3, and 4, respectively; thus MCV did not increase in an orderly progression along with HB and %Hb F. We studied the distribution of four anthropometric, five physical examination, and seven clinical measures of disease severity among clusters. In each sex, subgroups differed significantly (P less than .05) for percent ever hospitalized for sickle-cell anemia, percent ever transfused, and percent with bone-age delays greater than 1 year. In addition, male clusters differed significantly for percent ever having had pneumonia, priapism, or dactylitis, and females differed significantly for height and weight. %Hb F and its inverse relationship with %HBA2 was more highly associated with the measures of severity than the degree of anemia or MCV. This study establishes the utility of a vector of hematological variables as a predictor of heterogeneity of measures of clinical manifestations among young patients with sickle-cell anemia. The role of alpha-thalassemia and genetic factors that affect Hb F levels were considered as possible explanations for the observed heterogeneity.

Long survival in sickle cell anemia

Ten patients with sickle cell anemia surviving beyond the age of 40 were compared to 11 subjects with sickle cell anemia who died before that age. Hematologic and biochemical data as well as clinical and physical parameters of the two groups were compared. There was no statistically significant difference between the two groups with respect to the degree of anemia, severity of hemolysis, or hemoglobin A2 levels. A statistically significant difference was found between the two groups with respect to fetal hemoglobin, red cell zinc, and secondary sexual characteristics. Although the long survivors had fewer crises per year than the short survivors, the long-term complications such as leg ulcer, congestive heart failure, and aseptic necrosis of the hip were more common in the older patients. Cerebrovascular accidents were the cause of death in 9/11 short survivors and are absent in the long survivors. The alpha/beta chain synthesis ratio was normal in the long-survivor group and alpha gene mapping in five subject in that group revealed the genotype alpha alpha/alpha alpha in four and -alpha/alpha alpha in one. The older patients as a group had higher red cell zinc values. The secondary sexual characteristics were also better developed in the older subjects. The overall significance of zinc status and of a higher HbF on longevity of sickle cell anemia patients remains unknown.

Sickle cell haemoglobinopathies in England

Ninety-six Birmingham children with sickle cell disease were studied prospectively between 1969 and 1979. Thirty-five were homozygotes for HbS (SS), 12 had sickle thalassaemia (S thal), and 23 were double heterozygotes for HbS and C (SC). Twenty-six whose family studies were incomplete were classified as SS or S thal although most were thought to be SS. The average length of follow-up was 5.1 years. Four SS children and 1 SC child died, the annual mortality rates being 1.3% for SS and presumed SS, 0% for S thal, and 0.9% for SC children. The incidence of pulmonary illnesses and anaemic crises was greater than reported from Jamaica, while leg ulceration described there and in New York was not observed in Birmingham. Severe infections were less common than in the series reported from New York and no case of salmonella osteomyelitis was observed in Birmingham. In general the S thal and SC children had milder illnesses than the SS, and the SS children often showed impairment of growth and sexual maturation.

Hemoglobin variations on a small Bahamian island

Hemoglobino characteristic were investigated in 492 blood specimens collected in a small island community (1,450 inhabitants) in the Bahamas. Using two different methods, abnormal variants were detected in 20.3% of the sample, including genotypes AS, AC, AF(A/HPFH), SC, and SF. Biodemographic evidence suggests that the origin and distribution of the hemoglobinpathies in this population have been influenced by historical migrations and genetic drift. The opportunity for drift has been particularly heightened by the "founder effect," the maintenance of small population size, a relatively endogamous mating structure, and restricted immigration. Health survey results reveal a wide discrepancy between the actual prevalence of abnormal hemoglobins and that indicated by informant reports.

Erythrocyte adherence to endothelium in sickle-cell anemia. A possible determinant of disease severity

We studied 33 patients with sickle-cell anemia to examine the possible relation between the severity of their disease (frequency of microvascular occlusions) and the abnormal adherence of sickle erythrocytes to cultured human endothelium. Neither clinical severity nor erythrocyte adherence correlates significantly with red-cell indexes, hemoglobin concentration, percentage of irreversibly sickled red cells, level of fetal hemoglobin, or reticulocyte count. However, clinical severity and erythrocyte adherence are strongly correlated (rank correlation coefficient = +0.666; P less than 0.001). These findings are consistent with the hypothesis that abnormal interactions between erythrocytes and endothelium may be the initiating factor in the development of microvascular occlusions in sickle-cell anemia.

Hematological and clinical features of sickle cell diseases: a review

The differentiation, hematologic features and clinical manifestations of patients with the various sickling disorders are reviewed. The deficiencies in our current knowledge about the spectrum of the clinical course of patients with these conditions is discussed. The interaction of alpha thalassemia with sickle cell anemia and its possible effect upon the severity of the disease is summarized. The apparent milder disease in certain groups of patients with sickle cell anemia in whom there is an associated elevation of hemoglobin F is contrasted with the controversy surrounding the effects of hemoglobin F levels in the patients of African origin.

Sickle cell anemia and trait in southern India: further studies

Population surveys and family studies among 568 members of nine ethnic groups in southern India identified 15 homozygotes for sickle hemoglobin (HbS)who had mild clinical and hematological manifestations with high levels of fetal hemoglobin (mean=20%, range 8-36%) in a heterogeneous red cell distribution. In one family, the heterozygous mother had a hemoglobin pattern consistent with a form of the heterocellular hereditary persistence of fetal hemoglobin. Sickle cell trait was found in 153(27%) of those studied. Chromatographic quantitation of the hemoglobin fractions in these heterozygotes showed a trimodal distribution of the proportion of HB Sexplicable by a genetic model postulating the presence of genotypes with two (-alpha/-alpha), three (-alpha/alpha alpha) and four (alpha alpha/alpha alpha) active alpha-globin genes. Globin synthesis studies in four heterozygotes believed to have two active alpha-globin genes demonstrated an alpha/non-alpha total activity ratio (0.57) consistent with this model.

On the nature of sickle-cell disease in the Arabian Peninsula

The sickle-cell gene contributes substantially to the presentation of anaemia in certain areas of the Arabian Peninsula. However, the clinical presentation of the homozygous state of Hb S is less severe than that observed in other ethnic groups, such as American negroes. In the present paper, biosynthesis studies performed on reticulocytes from heterozygotes and homozygotes for the Hb S give further indications of the mild nature of sickle-cell disease in Arabia. Comparison of two affected families, from Saudi Arabia and Jordan, showed that clinical manifestation of the disease is mirrored by the biochemical and haematological findings in affected individuals. The results are discussed in terms of the effect of co-existing thalassaemia and/or iron deficiency with Hb S. It is suggested that both genetic and acquired conditions play a role in the clinical features of the disease. The mechanisms responsible for regulation of alpha-chain synthesis by iron (haem) deficiency are discussed.

Erythrocyte calcium abnormalities and the clinical severity of sickling disorders

We studied erythrocyte calcium levels and uptake in a group of patients with sickle haemoglobinopathies of different clinical severity in an attempt to relate these measurements to the production of irreversibly sickled cells and disease severity. Erythrocyte calcium levels were measured by atomic absorption spectroscopy and calcium uptake by isotopic means. In sickle cell anaemia, erythrocyte calcium content was elevated and the uptake of isotopic calcium increased under both oxygenated and deoxygenated conditions. There was a direct correlation between the numbers of irreversibly sickled cells and calcium uptake and an inverse relationship between calcium uptake and red cell potassium level. The clinical course of disease was milder in patients with high fetal haemoglobin levels, but there was no relationship between clinical course and calcium levels, calcium flux or irreversibly sickled cells. Our observations suggest that calcium accumulation and irreversibly sickled cell formation are related processes. The absence of good correlation between various biochemical and clinical parameters emphasizes the complexity of factors which modify the clinical course of this disorder.

Sickle cell syndromes. II. The sickle cell anemia-alpha-thalassemia syndrome

Five American black patients, ages 1 to 16 years, with the sickle cell anemia-alpha-thalassemia syndrome are described. Each patient had persistent microcytosis not explained by iron deficiency, and in each family the presence of alpha-thalassemia in combination with sickle cell trait was demonstrated in one of the parents. In one patient, in whom the diagnosis of sickle cell anemia was established at birth, an elevated level of Barts (gamma4) hemoglobin was also found. In these patients levels of alkali-resistant hemoglobin and reticulocyte counts were similar to those of sickle cell anemia patients of comparable age; however, stained smears of their peripheral blood rarely showed the presence of irreversibly sickled cells. No major ameliorative effect of the alpha-thalassemia on the clinical expression of the sickle cell disease of these patients was evident.

Mild sickle-cell anaemia in Iran associated with high levels of fetal haemoglobin

Sixteen subjects, with sickle-cell anaemia, all Iranians (ages 3 to 56 years), with very mild symptomatology are reported. Some of the subjects had been totally asymptomatic. Splenomegaly was noted in 9 cases. There was an increase in the mean level of fetal haemoglobin (18%); this is the probable explanation for the mild phenotype. In 29 subjects with sickle-cell trait, the level of HbF was also significantly raised as compared with normal (1-6% vs. 0-6%). The mechanism of increased synthesis of HbF is unknown. The findings are similar to those reported in the Shiite Moslems of Saudi Arabia suggesting that in these populations there is a genetically-determined ability to produce high levels of Hb F in the presence of the sickle-cell gene.

Sickle cell anemia: erythrokinetics, blood volumes, and a study of possible determinants of severity

The variability in the clinical expression of sickle cell anemia led us to study factors which might influence the course of this disease. We examined erythrokinetics, blood volumes, and variables which influence hemoglobin function in a group of adults with sickle cell anemia of varying degrees of clinical severity. We were unable to correlate any single measurement with the clinical course; however, our patient sample was small and the data suggested areas for further study. An expansion of plasma volume noted in all patients. This made it difficult to predict red cell mass from the hemoglobin level, which consistently underestimated its magnitude. The red cell production index and iron turnover values indicated that there is often a suboptimal erythropoietic response to anemia in sickle cell disease.

On the birth of an infant with sickle cell anemia

This is the first report in the English literature of the birth of an obligate SS infant whose parents both had sickle cell anemia. The young adult SS parents of this infant and their families did not wish to prevent the birth of this child but had, in fact, many positive reasons to continue the pregnancy to term even in the face of the increased personal risk of pregnancy for this mother. This unusual circumstance initiated a re-appraisal of the realistic expectations with respect to reproduction in patients with homozygous recessive genetic disorders. No definitive studies could be found which attempted to evaluate the influence of genetic counseling on reproductive behavior in patients with sickle cell anemia. The questions raised about the 'right to reproduce' and the realistic aims of genetic counseling in adult homozygote patients have been discussed. However, no conclusions seem warranted because of the paucity of available information.

Sickle cell anemia and trait in a population of southern India

In an ethnic group in southern India, the Irula, seven individuals with sickle cell anemia were found to manifest only mild illness. Although a relatively high level of fetal hemoglobin was present in one, none of the factors thought to ameliorate the course of sickling disorders could be identified in the remaining six. In a random population survey, sickle hemoglobin was found in 90 of 292 Irula (31%). In those with sickle cell trait, the proportion of sickle hemoglobin in hemolysates (mean = 26%, range 19-32%) was substantially lower than that reported for any other population.