Acute splenic sequestration in HbSS: observations from the Jamaican birth cohort.

OBJECTIVE: To document the prevalence, clinical features, haematology and outcome of acute splenic sequestration (ASS) in homozygous sickle cell disease (HbSS). STUDY DESIGN: A cohort study from birth. SETTING: The Medical Research Council Laboratories at the University of the West Indies, Kingston, Jamaica. PATIENTS: 311 cases of HbSS detected during the screening of 100 000 deliveries at the main government maternity hospital between 1973 and 1981. INTERVENTIONS: Long-term follow-up and free patient care focusing on ASS. MAIN OUTCOME MEASURE: Acute splenic sequestration. RESULTS: There were 183 episodes of ASS in 105 patients representing 35% of the cohort. The median age for first event was 1.07 years. During ASS, median values for haemoglobin fell by 32 g/dL, reticulocytes increased by 8% and total nucleated cells increased by 10.5%. ASS recurred in 47 (45%) patients. Conservative therapy in 133 episodes of 85 patients was associated with five deaths and splenectomy in 20 patients with 50 episodes had no deaths. Symptoms were generally non-specific but acute chest syndrome occurred in 17, and blood cultures revealed coagulase negative staphylococci in 5. The ASS case fatality rate was 3.6% and may be higher if autopsy evidence of ASS is included. There was no seasonal pattern but higher levels of fetal haemoglobin predicted patients less prone to ASS and its later occurrence. CONCLUSIONS: ASS remains an important cause of morbidity and mortality in HbSS in developing societies. ASS appears to be a non-specific response to many possible risk factors including coagulase negative staphylococci.

Spleen size in homozygous sickle cell disease: trends in a birth cohort using ultrasound.

OBJECTIVES: To provide ultrasound baselines for spleen length in homozygous sickle cell disease (HbSS) and in normal controls with a HbAA genotype. METHODS: The Jamaican cohort study identified 311 babies with HbSS and 246 matched HbAA controls during the screening of 100,000 consecutive deliveries in Kingston, Jamaica from 1973 to 1981. Ultrasonography commenced in 1988 when the youngest patients were aged 6 years at which time deaths, emigrations and default had reduced the numbers to 206 HbSS and 89 controls. It continued annually until 2000. RESULTS: The spleen was visualized in all HbAA controls but in only 1103/2138 (52%) scans in HbSS. Where available, mean splenic lengths were significantly lower in HbSS (77-103 mm in males, 70-83 mm in females) compared to normal controls (89-101 mm in males, 86-95 mm in females). Assessed by statistical modelling after adjusting for body height, the splenic ratio (splenic length/body height) declined over the age range 12-20 years in HbSS, consistent with progressive splenic fibrosis. Genetic factors known to inhibit sickling, α thalassemia and fetal hemoglobin level (HbF) significantly reduced the decline in splenic ratio. Clinical splenomegaly was an insensitive measure of splenic enlargement as only 50% of patients aged 18 years and above with spleens measuring ≥150 mm on ultrasonography had palpable spleens. CONCLUSIONS: An age-related decline in splenic length occurred in HbSS and occurred more slowly with genetic factors known to inhibit sickling. The standards provided may be of value in assessing minor degrees of subclinical acute splenic sequestration. ADVANCES IN KNOWLEDGE: These are the first standards available for splenic length in HbSS. They may be useful in detecting red cell sequestration, not apparent from clinical splenomegaly and also provide a model for identifying factors inhibiting vaso-occlusion.

Newborn screening for abnormal haemoglobins in Jamaica: Practical issues in an island programme.

OBJECTIVE: To report the diagnostic challenges of newborn screening for abnormal haemoglobins. SETTING: Cord blood samples from 13 hospitals in southwest Jamaica taken in 2008-2019. METHODS: Blood spots, collected from the umbilical cord, were analysed by high pressure liquid chromatography (HPLC) to reveal phenotypes for HbSS and HbCC, but genotype confirmation may require parental studies or gene sequencing. Such cases that were successfully traced were analysed in this follow-up study. RESULTS: HPLC screening of 121,306 samples detected HbAS in 11,846 (9.8%), HbAC in 4508 (3.7%) and other electrophoretic abnormalities in 1090 babies. Among 101 previously unconfirmed cases, 34/90 (38%) with HPLC evidence of a HbSS phenotype had other genotypes, and 7/11 (64%) with a HbCC phenotype had other genotypes. Syndromes from the interaction of ß thalassaemia occurred in 112 babies (85 with HbS, 27 with HbC) and of genes for hereditary persistence of fetal haemoglobin (HPFH) in 18 (12 with HbS, 6 with HbC). Variants other than HbS and HbC occurred in 270 babies, 16 in combination with either HbS or HbC, and 254 as traits. Most variants are benign even when inherited with HbS, although HbO Arab, HbD Punjab, or Hb Lepore Washington, which occurred in 6 cases, may cause sickle cell disease. CONCLUSIONS: Genes for ß thalassaemia and HPFH are common in western Jamaica and when associated with HbS may present diagnostic challenges in newborns, as HbF and HbA2 have not reached diagnostic levels. Family and DNA studies may be necessary for genotype confirmation.

Causes of death and early life determinants of survival in homozygous sickle cell disease: The Jamaican cohort study from birth.

Globally, the majority of persons born with sickle cell disease do not have access to hydroxyurea or more expensive interventions. The objectives were to estimate the survival in homozygous sickle cell disease, unbiased by symptomatic selection and to ascertain the causes of death in a pre-hydroxyurea population. The utility of early life biomarkers and genetically determined phenotypes to predict survival was assessed. A cohort study based on neonatal diagnosis was undertaken at the Sickle Cell Unit, a specialist clinic delivering care to persons with sickle cell disease in Jamaica. Screening of 100,000 deliveries detected 315 babies with homozygous sickle cell disease of whom 311 have been followed from birth for periods up to 43 years. Pneumococcal prophylaxis and teaching mothers splenic palpation were important, inexpensive interventions. Anticipatory guidance, routine care and out-patient acute care were provided. Each participant was classified as alive, dead, or defaulted (usually emigration). Causes of death were ascertained from clinical records and/or post-mortem reports. Survival was assessed using the Kaplan-Meier function. Sex-adjusted Cox semi-parametric proportional hazards and Weibull modelling were used to assess the effects on survival of biomarkers. Survival to 40 years was 55.5% (95% CI 48.7% to 61.7%). Acute Chest Syndrome (n = 31) and septicemia (n = 14) were significant causes of death at all ages. Acute splenic sequestration (n = 12) was the most common cause of early deaths. Survival was significantly shorter in those with lower hemoglobin at 1 year, high total nucleated count at 1 year, and a history of dactylitis ever. In these hydroxyurea naïve patients, survival into midlife was common. Causes of death were often age specific and some may be preventable. Early life biomarkers predictive of decreased survival in SS disease identify a patient group likely to benefit from close clinical supervision and potentially high risk therapies.

ß-Thalassemia Mutations in Jamaica: Geographic Variation in Small Communities.

Over the last 43 years, surveys of over 200,000 subjects in Jamaica have identified ß-thalassemia (ß-thal) mutations. In most, these genes were detected at birth in patients with sickle cell-ß-thal and so the prevalence and distribution would not be influenced by subsequent clinical course. There were two newborn populations, 100,000 deliveries in the corporate area between 1973-1981 and 84,940 in south and western Jamaica between 2008-2016. A third population, which derived from the Manchester Project in central Jamaica, screened 16,612 secondary school children, aged predominantly 15-19 years, and identified 150 students with the ß-thal trait and 11 with sickle cell [Hb S (HBB: c.20A>T)]- or Hb C (HBB: c.19G>A)-ß-thal. The latter patients may have been subject to symptomatic selection, but this should not have affected those with ß-thal trait. Of the 24 different molecular mutations, ß0-thal genes accounted for 10.0-27.0% of these groups and most common was IVS-II-849 (A>G) (HBB: c.316-2A>G). Of the ß+ mutations, seven subjects had severe genes with low levels of ß chain synthesis but the majority were benign mutations in the promoter region. The -29 (A>G) (HBB: c.-79A>G) mutation dominated in the newborn study in Kingston, similar to experiences in Guadeloupe and African Americans but the -88 (C>T) (HBB: c.-138C>T) mutation was more common among school students in central Jamaica. Caribbean populations are genetically heterogeneous but variations within different parts of Jamaica is of potential importance for prenatal diagnosis and genetic counseling. This information may also be useful among the large Jamaican diaspora.

Prevention of sickle cell disease: observations on females with the sickle cell trait from the Manchester project, Jamaica.

Screening for haemoglobin genotype was offered to senior school students in Manchester parish in south central Jamaica to test whether this knowledge would influence choice of partner and reduce births with sickle cell disease. Over six academic years, 15,539 students, aged mostly 15-19 years, were screened with voluntary compliance rising from 56 to 92 % over this period. All subjects were given permanent genotype cards and carriers of abnormal genes were offered counselling which explained the reproductive options but avoided recommendations. Prior to screening, all had been offered illustrated lectures on the genetics and clinical features of sickle cell disease. The current study, confined to females with the sickle cell trait, interviewed 763/845 (90.3 %) subjects seeking to assess retention of this knowledge and their response to subsequent boyfriends. Of those interviewed, 42 subjects were excluded (38 emigrated, one died, three received incorrect genotype cards) leaving 721 with complete information. Knowledge of genotype was retained in 95 %, the outcome of future offspring correctly recalled in 91 %, and haemoglobin genotype cards were still possessed by 89 %. A current 'boyfriend' was acknowledged in 403 (56 %) of whom the partner's genotype was known in 88 (74 determined by the project laboratory; 14 by other laboratories) and unknown in 315 (78 %). Offers of free blood tests to all these partners were accepted by only 14 (4 %). Seventeen (2.4 %) were married but the husbands genotype was known in only five (four AA, one AS) of these. Most subjects retain knowledge of their genotype and of its significance for having affected children but the reluctance of partners to be tested was a major obstacle.

Elevated IL-1α and CXCL10 serum levels occur in patients with homozygous sickle cell disease and a history of acute splenic sequestration.

Acute splenic sequestration (ASS) and chronic hypersplenism are common features of homozygous sickle cell (SS) disease in the first 5 years of life affecting one-third of subjects in the Jamaican Cohort Study. The risk factors are largely unknown and the current study explores a possible role of genetic factors. We have explored these in subjects who received splenectomy in the management of ASS (n=8) or chronic hypersplenism (n=9) along with age, gender, and genotype matched controls using Luminex Technology to assess 42 human cytokines/chemokines, including IL-1α and CXCL10 (IP-10). Levels of IL-1α (p=0.008) and CXCL10 (p=0.009) were significantly elevated in patients treated by splenectomy compared with the control group. Levels of IL-1α were significantly higher in those with a history of ASS compared with matched normal controls (p=0.028) but not in those treated for hypersplenism (p=0.093). Furthermore, several significant differences were found in the median ratios of some cytokine biomarkers between the splenectomized group and the normal controls. These observations are consistent with acute splenic sequestration having a distinct phenotype which may be helpful in predicting those at risk of this complication and suggest that the mechanism of these differences merit further study.

Screening for the beta-thalassaemia trait: hazards among populations of West African Ancestry.

The aim of this study was to examine the accuracy and characteristics of detecting the beta-thalassaemia trait in populations of West African ancestry. School children, aged 16-19 years, in Manchester Parish, Jamaica were screened to detect the genes which could give rise to offspring with sickle cell disease. Haematological indices and HbA(2) levels in subjects with an MCH ≤ 26 pg and an RDW < 18.0 with DNA analysis in those with indices consistent with the beta thalassaemia trait were measured. The performance of published discriminant indices in distinguishing iron deficiency and beta-thalassaemia trait in this population was assessed. Of 10,148 subjects, 1,739 (17.1%) had an AA haemoglobin phenotype and red cell indices consistent with beta-thalassaemia (MCH values ≤ 26 pg, RDW < 18.0) requiring estimations of HbA(2) levels. HbA(2) levels were ≥3.5% in 112 and beta-thalassaemia mutations were identified in 77 of these including the -88 C>T mutation in 35 (45%), -29 A>G in 19 (25%), -90 C>T in 7 (9%), the IVS II-849 A>G in 5 (6%) with smaller contributions from five other mutations. Discriminant indices performed poorly in the differentiation of iron deficiency and the beta-thalassaemia trait. Detection of the beta-thalassaemia trait is relatively insensitive in populations of West African ancestry partly because of the mild defects characterising beta-thalassaemia in this population and also the high prevalence of deletional alpha thalassaemia. More sensitive indicators are required for beta-thalassaemia detection to inform such populations at risk of offspring with sickle cell disease.

The haematology of homozygous sickle-cell disease - abstract

The purpose of the study was to investigate age- and sex-related variations in the haematology of older patients with SS disease, in order to determine haematological characteristics possibly favouring survival. Steady state haematology was available in 181 patients aged 40-73 years. There appeared to be no consistent sex differences in any of the indices examined. Longitudinal analyses were performed for the 133 patients with at least two observations, using analysis of covariance (ANCOVA) methods. Highly significant declines in total haemoglobin (Hb), platelet counts and absolute reticulocyte count were displayed in both sexes. Overall, Hb levels decreased by approximately 0.076 gm/dl/year in females and 0.113 gm/dl/year in males. Significant increases occurred in HbA, HbF and MCV in females only. The total nucleated count (NBC) fell with age, although the decline was only significant in females. These observations are consistent with a progressive bone marrow failure which is not explained by the commonly occurring renal impairment in older SS patients since the changes persisted in analyses confined to the 84 patients with normal creatinine levels (C=120 æmol/l). The mechanism for this bone marrow failure is currently unknown. The prevalence of homozygous alpha thalassaemia in the study group (4.4 percent) was similar to that in the overall SS population, providing no evidence that this may lead to improved survival, as has been suggested (AU)

The red cell distribution width in sickle cell disease: is it of clinical value?

The red cell distribution width (RDW) has been studied during the clinical steady state in 1121 patients with homozygous sickle cell (SS) disease, 344 with sickle cell-haemoglobin C (SC) disease, 68 with sickle cell-beta+ thalassaemia, 49 with cell beta§ thalassaemia and in 130 control subjects with a normal (AA) genotype. The mean RDW was moderately increased in Sbeta+ thalassaemia and SC disease and markedly increased in Sbeta§ thalassaemia and SS disease. In SS, SC and Sbeta§ thalassaemia genotypes, lower RDW values occurred in females and with alpha thalassaemia. The RDW correlated negatively with total haemoglobin, mean cell haemoglobin concentration, mean cell volume and fetal haemoglobin (HbF) and positively with reticulocyte count in SS disease. A low RDW was associated with higher weight and less frequent dactylitis, painful crisis, acute chest syndrome, acute splenic sequestration and hospital admissions. A low RDW in SS disease is consistent with a high total haemoglobin, high HbF, low reticulocyte count, alpha thalassaemia and a more mild clinical course. (AU)

Alpha thalassemia and the hematology of homozygous sickle cell disease in childhood

Alpha thalassemia modifies the gematolic expression of homozygous sickle cell (SS) disease, resulting in increased total hemoglobin and HbA2 and decreased HbF, mean cell volume, reticulocytes, irreversibly sickled cells, and biliru-bin levels. The age at which these changes develop in children with SS disease is unknown. Ascertainment of globin gene status in a large representative sample of study the gematologic indices in nine children homozygous for Alpha thalassemia 2 (two-gene group), 90 children heterozygous for Alpha thalassemia 2 (three-gene group), and 167 children with a normal Alpha globin gene complement (four-gene group). The two-gene group had significantly lower mean cell volumes from birth, higher red cell counts from one month, lower reticulocytes from three months, and higher HbA2 levels from one year, as compared with the four-gene group. Children with three genes had intermediate indices but resembled more closely the four-gene group. Differences in total hemoglobin or in fetal hemoglobin between the groups were not apparent by eight years of age. The most characteristic differences of the two-gene group were the raised proportional HbA2 level and low mean cell volume, the latter having some predictive value for Alpha thalassemia status at birth.(AU)

The haematology of steady state homozygous sickle cell disease: frequency distibutions, variation with age and sex, longitudinal observations

The steady state haematological characteristics observed in 1071 patients with homozygous sickle cell (SS) disease aged 5-66 years are presented (Summary)

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 x-thalassaemia. Patients with coexisting x-thalassaemia showed a significant increase in erythrocyte deformability measured as filtration of washed erythrocytes through 5 um 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 x-thalassaemia 2 on haematological parameters and clinical events in homozygous sickle cell disease (AU)

A trial of folate supplementation in children with homozygous sickle cell disease

A double blind controlled trial of supplementation with folic acid has been performed in 117 children with homozygous sickle cell (SS) disease aged 6 months to 4 years over a 1 year period. No megaloblastic change was observed in either group. At the end of the study period the folate supplemented group showed no significant differences in haemoglobin, growth characteristics, or in the proportion of children affected by major or minor infections, acute splenic sequestration, dactylitis or episodes of bone or abdominal pain. However, the folate supplemented groups showed a significantly lower mean cell volume and the placebo group contained a significant excess of children experiencing multiple episodes of datylitis. The results are compatible with mild folate deficiency in some patients in the placebo group but the absence of striking effects on haematology or growth suggest that the policy of regular folate supplementation in children with SS disease should be critically reviewed (AU)

Post-natal decline of fetal haemoglobin in homozygous sickle cell disease: relationship to parental 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 cell (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 onwards but, unlike the normal controls, no sex differences 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 á-like globin gene complex and be in linkage disequilibrium with the áý allele (Summary)

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

Patients with homozygous sickle-cell disease may be homozygous for alpha-thalassemia 2 (O-/O-), may be heterozygous for alpha-thalessemia 2 (O-/OO), or may have a normal alpha-globin-gene complement (OO/OO). 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 Aý, 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 billirubin levels, than those with a normal alpha-globin-gene complement. Heterozygotes (O-/OO) 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 the other two subgroups. These data confirmed 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 is discovered.(AU)

Outbreak of aplastic crises in sickle cell anaemia associated with parvovirus-like agent

Since 1952, 112 childen with sickle cell anaemia (SCA) in Jamaica have had an aplastic crisis. Outbreaks occurred in 1956, 1960, 1965-67, 1971-73, and 1979-80. Most cases occurred in children under 10 years of age, and an aplastic crisis in a patient over the age of 15 years is rare. There were 38 cases in 1970-80 and stored serum specimens from 28 of these were available for virus studies. Evidence for infection with a parvovirus-like agent was found in 24 of these 28 cases. Viral antigen was detected in 2 patients, both of whom demonstated seroconversion. Serconversion during 1980 was detected in a further 7, increasing amounts of antibody during the convalescent period were found in 5, antibody was found in 2 of 4 patients from whom only an acute phase specimen was available and the remaining 10 were antibody positive in the only convalescent phase sample available for testing. Antibody was found in 4 of 94 controls with the SS genotype (in retrospect 2 of these may have had an aplastic crisis) and in 17 percent of 48 controls with a normal haemoglobin (AA) genotype. The results accord with the possibility that the parvovirus-like agent is the principal cause of aplastic crisis in SCA (Summary)

The development of haematological changes in homozygous sickle cell disease: a cohort study from birth to 6 years

A cohort study of sickle cell disease from birth has allowed observations on the disease without the symptomatic selection inherent in previous series. The development of haematological indices from birth to 6 years in male and female infants with homozygous sickle cell (SS) disease is presented and compared with values in age and sex matched controls with a normal haemoglobin (AA) genotype previously presented elsewhere. In SS disease total haemoglobin levels fell rapidly from birth to a plateau at 3-6 months before falling again to 15 months after which no age related change occured. Mean cell haemoglobin concentration fell from birth to lowest values at 15-18 months before increasing to reach the level present at birth by the age of 5 years. Red cell counts fell rapidly after birth to a plateau at 2 months, increased slightly to 2 months and then fell steadily throughout the remaining period of study. The mean cell voloume and mean cell haemoglobin also fell rapidly after birth reaching the lowest values by 6 months and then increased progressively. Female patients showed significantly higher haemoglobin levels from 15 months to 4« years. Compared to AA controls, SS patients manifested significantly lower levels of haemoglobin from 2 weeks, and red cell counts from 1 month, and significantly higher levels of MCHA from 4 months to 3 years, MCV from 8 months to 5 years, and serum iron levels from 1 to 4 years. Children with SS disease were partially protected from iron deficiency in early childhood, perhaps by increased intestinal absorption of iron, and the associated increase in intracellular haemoglobin concentration might be disadvantageous during this high risk period (Summary)