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.

A Plea for the Newborn Diagnosis of Hb S-Hereditary Persistence of Fetal Hemoglobin.

The gene for hereditary persistence of fetal hemoglobin (HPFH) in the Caribbean is much more common than previously estimated. To avoid labeling persons with the benign syndrome Hb S (HBB: c.20A>T)/HPFH as a disease and wasting scarce resources, parental studies are recommended when newborn screening reveals a pattern consistent with an SS phenotype.

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.

Hb S-ß-thalassemia: molecular, hematological and clinical comparisons.

Clinical and hematological features are presented for 261 patients with identified ß-thalassemia (ß-thal) mutations. Mutations causing Hb S [ß6(A3)Glu→Val]-ß(0)-thal were IVS-II-849 (A>G) in 44%, frameshift codon (FSC) 6 (-A) in 14%, Hb Monroe [ß30(B12)Arg→Thr] in 14%, and IVS-II-1 (G>A) in 10%. Mutations causing Hb S-ß(+)-thal with 14-25% Hb A (type III) were -29 (A>G) mutation in 60%, -88 (C>T) in 22% and the polyadenylation signal site (polyA) (T>C) mutation in 14%, and in Hb S-ß(+)-thal with 1-7% Hb A (type I), all had the IVS-I-5 (G>C) mutation. Hematologically, only minor differences occurred between the four Hb S-ß(0)-thal mutations, but among the three mutations causing Hb S-ß(+)-thal type III, levels of Hb A(2), Hb F, hemoglobin (Hb), MCV and MCH were highest in the -88 and lowest in the polyA mutations. Clinically, Hb S-ß(0)-thal and Hb S-ß(+)-thal type I were generally severe, and Hb S-ß(+)-thal type III disease with the -88 mutation was milder than that caused by the polyA mutation.

Odisha Revisited: A Personal Account.

In 1986, a paper in the Lancet was the first to collate hematology, molecular findings, and clinical features of homozygous sickle cell (SS) disease in India. The paper came from the group organized by Professor Bimal Kar in Burla Medical College, Sambalpur University, in western Odisha. Although widely quoted, few readers will be aware of the history of this work that is now attached in an informal summary.

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.

Leg ulceration in sickle cell disease: medieval medicine in a modern world.

Leg ulceration is now recognized as an important complication of sickle cell disease, especially of the SS genotype. Since there is no convincing evidence of delayed healing of operation scars or of wounds elsewhere in the body, it must be concluded that factors specific to the lower leg render patients prone to delayed healing at this site. Many lesions are traumatic in origin and since there is considerable variation in healing rates among the normal population, it is useful to define chronic leg ulceration on the basis of a minimal duration, which in Jamaican studies has required at least 3 months and sometimes 6 months before healing. This minimal duration avoids the difficulties of interpreting the significance of briefer lesions since the moment of final healing may be poorly defined (patients may conclude that a scab represents healing whereas small lesions persist beneath) and often goes undocumented as patients may not report and medical attendants may not enquire, the date of final healing.

Jamaican sickle cell disease: lessons from a cohort study

The Jamaican Cohort Study of sickle cell disease recruited all cases among 100 000 consecutive non-operative deliveries at the Government Maternity Hospital (Victoria Jubilee) between June 1973 and December 1981. There were 315 babies with homozygous sickle cell (SS) disease of whom 311 were followed from birth with active tracing of defaults. During this period, prophylactic penicillin and pneumococcal vaccine were introduced for the prevention of pneumonococcal septicaemia, and parental education in the early detection of acute splenic sequestration was shown to reduce mortality from this complication by 90 percent. To assess changes in survival consequent on these measures, 315 children were divided into three equal groups of 105 children born between 25/6/73 and 27/12/75 (30 months), 28/12/75 and 2/1/79 (36 months), and 3/1/79 and 28/12/81 (36 months). Mortality was assessed by survival curve analysis using the product limit method. Survival was examined from birth to the 15th birthday, and survival curves for each third compared using the log rank test for trend. There were 61 deaths (54 autopsies) before 15 years of age, 28 in the first third, 17 in the second third, and 16 in the last third, the log rank test for trend being of borderline statistical significance (p=0.05). Septicaemia or meningitis accounted for 8, 1 and 5 deaths in the three groups, respectively, and pneumococcal sepsis for 4, 1 and 1 of these deaths. Acute splenic sequestration accounted for 5, 2 and 1 deaths and the interventions (against pneumococcal sepsis and acute splenic sequestration) were assessed by combining these for anlaysis. Together they showed a significant decline in mortality during the study (test for trend, p=0.02). No change was observed in the numbers with acute chest syndrome. Early diagnosis and simple prophylactic measures significantly reduce deaths associated with SS disease.(AU)

Management of sickle cell disease; lessons from the Jamaican Cohort Study

Sickle cell disease is enormously variable in its expression and outcome. In addition to this intrinsic variablity are the problems of symptomatic selection biasing observations towards the sever end of a wide clinical spectrum and a truly changing natural history as a result of better management. Against this background, there was a need for a description of the disease in a truly representative sample of patients and this objective has been approached in the Jamaican Cohort Study of Sickle Cell Disease. Initiated in 1973, this study is based on all cases of sickle cell disease detected among 100,000 consecutive normal deliveries in Kingston, Jamaica. All affected children as well as age matched normal controls have been followed prospectively and are currently ages 11 to 19 years. The following review is based on lessons learnt from this cohort study. It is not intended to be a comprehensive survey of knowledge of sickle cell disease and does not address major contributions from studies elsewhere. In some ways, therefore, the review may appear unbalanced because of this specific objective. However, a great deal has been learnt about the evolution of the abnormal haematology of sickle cell disease and its relationship to clinical features. The causes of early mortality in sickle cell disease in Jamaica are described and the major complications such as acute splenic sequestration, pneumococcal septicaemia, aplastic crisis, hypersplenism, and acute chest syndrome have been addressed with varying success. Overall survival to the age of 19 years has been 75 percent and it is planned that the study should continue to define the problems of late adolescence and early adult life (AU)

A comparison of erythrocyte characteristics in sickle cell syndromes in Jamaica

Red-cell characteristics were studied in the steady state in 3 sickle-cell syndromes, homozygous sickle-cell disease (SS), sickle-cell/heamoglobin-C disease (SC), and sickle-cell/á-thalassaemia (S/thal). Hb-SC disease had the highest haemoglobin levels, red cells counts, and mean corpuscular haemoglobin concentrations, all of which may contribute to the high thrombotic tendency noted in this disease. The two types of S/thal (with and without Hb A) generally had different haematological features. The non-Hb-A type of S/thal, which may resemble SS disease on electrophoretic techniques and present a diagnostic problem, was distinguishable on many red cell characteristics reported here (Summary)

Red cell size and the clinical and haematological features of homozygous sickle cell disease

The contribution of red cell (mean cell volume) to the clinical and haematological manifestations of homozygous sickle cell (SS) disease has been investigated by comparing the-/* features of two groups of patients with low (<80 fl) and high (>95 fl) MCV values after matching for age, sex, and fetal haemoglobin level. The microcytic group manifested significantly higher Hb, PCV, RBC and HbAý levels and significantly lower reticulocyte and irreversibly sickled-cell counts. Clinical features were not less severe in the microcytic group, splenomegaly persisting for longer and painful crises were more common although the latter difference did not reach significance. The milder haematological picture associated with decreased intravascular sickling was not reflected in a more mild clinical course. It is postulated that the higher vicosity accompanying the higher haemoglobin levels in microcytic patients may offset the rheological advantages of decreased intravascular sickling (Summary)

Microchromatographic quantitation of hemoglobin A levels in phenotypes of sickle cell-beta thalassemia

The inheritance of the sickle cell gene in combination with a gene for á+ thalassemia results in a spectrum of sickle cell-á+ thalassemia syndromes with varying levels of hemoglobin A (HbA). Some severe sickle cell-á+ thalassemia syndrome have small amounts of HbA, which may be difficult to quantitate in the presence of fetal hemoglobin. A microcolumn chromatographic method, using 0.5 M Tris-acetic acid developers with varying pH values from 9.0 to 6.0 appears to adequately quantitate small amounts of HbA. This method is relatively simple and cheaper than high-performance liquid chromatography, a major consideration in developing countries.(AU)

Serum transferrin receptor levels in homozygous sickle-cell disease - abstract

Transferrin receptors are used by rapidly dividing tissues such as bone marrow for the extraction of iron necessary for their metabolic requirements. As cells in the erythropoietic series mature, transferrin receptors are cleaved from the cell surface and may be measured free in the plasma. Serum transferrin receptors (STR) levels are therfore believed to reflect the extent of erythropoiesis and are elevated in anaemias associated with iron deficiency, haemolysis and thalassaemia and decreased in aplastic anaemia. Levels have been measured in stored sera from 182 children with homozygous sickle-cell (SS) disease and 42 controls with a normal haemoglobin (AA) genotype age 8 years (ñ 3 months) in a cohort study from birth. Levels is SS children (mean, SD: 38.3, 12.7) greatly exceeded those in AA controls (6.7, 1.9) (test = 32.1, p0.001) and were negatively correlated with total haemoglobin and foetal haemoglobin levels in both sexes but not with reticulocyte counts. The serum transferrin receptor level may be a useful indicator of the degree of eryreticulocyte counts. The serum transferrin receptor level may be a useful indicator of the degree of erythropoietic expansion in SS disease, and requires further study to determine its clinical value (AU)

Chromatographic quantitation of HbA levels for distinguishing genotypes of sickle-cell á+ thalassaemia - abstract

Sickle-cell á+ thalassaemia represents a spectrum of conditions, depending on the molecular basis of the á+thalassaemia gene. Different genes manifest different levels of beta chain synthesis and hence varying amounts of HbA. Different á+thalassaemia genes also characterise sickle-cell á+thalassaemia in different groups, several of which occur in Jamaica. Commonest among people of African ancestry are the -29 and -88 substitutions which result in a very mild sickle-cell á+thalassaemia type III associated with high HbA levels (18 - 25 percent). The Indian population manifests more severe genes causing sickle-cell, á+thalassaemia type II with 8 - 15 percent HbA and sickle-cell á+thalassaemia type I with 3 - 5 percent HbA. Estimation of the level of HbA is therefore useful in predicting the probable molecular basis for the á+thalassaemia gene and also the expected clinical course. Measurement of HbA by chromatography in sickle-cell á+ thalassaemia requires adequate separation from both HbS and HbF and anew method is presented which appears to give satisfactory results. The method is based on 0.5M Tris-5 percent acetic acid. Duplicate runs on blood samples from 28 patients gave mean (SD) values of 17.4 (6.7) and 17.2 (6.9) with between-run differences of 0.2 (95 percent C.I.,-0.7, 1.1) p = 0.65; 95 percent of the differences between runs were 4.7 percent or less. HbA measurements with this method did not allow the same grouping as in Greece, which may be due to differences in the two populations or to measurement error. The method is relatively simple and of considerably lower cost than high-performance liquid chromatography (HPLC) (AU)

Comparison of haematological features of the ᧠and á+ thalassaemia traits in Jamaican negroes

Haematological characteristics have been compared in 29 subjects with heterozygous ᧠thalassaemia and in 33 subjects with heterozygous á+ thalassaemia, identified by the type of sickle-cell-á thalassaemia among close relatives, in a Jamaican Negro population. Total haemoglobin, MCV and MCH were significantly lower in the ᧠type but the level of Hb A2 was not significantly different. Individual values for MCV, MCH and Hb A2 in the 225+ type occasionally overlapped those in the normal population casting doubt on the adequacy of these criteria in identifying all cases of heterozygous á+ thalassaemia. The haematological differences are those which would be expected on theoretical grounds. The inability to confidently differentiate the two types of heterozygous á thalassaemia has implications for genetic counselling. The inability to distinguish heterozygous á+ thalassaemia from normals on any single haematological index suggests that surveys depending on estimations of Hb A2 or on MCV alone may have underestimated the prevalence of the á+ thalassaemia gene. (AU)

The clinical features of haemoglobin SC disease in Jamaica

The clinical and haematological features of 90 Jamaican patients with haemoglobin SC disease are reviewed. Mean haemoglobin levels indicated mild anaemia although individual haemoglobin levels were often within the normal range. The clinical features were qualitatively similar to those of homozygous sickle cell disease(SS disease) although they were generlly less frequent and of lesser severity. Ocular pathology was an exception, occuring more frequently in SS disease even in age-sex-matched groups. There is some evidence that the higher haemoglobin level in SC disease may be aetiologically related to retinal vascular disease. (AU)

Screening cord bloods for detection of sickle cell disease in Jamaica

A cord-blood screening program, designed primarily for detecting sickle cell disease, has been in operation for seven months (8 000 samples) at a large maternity unit in Kingston, Jamaica. We describe techniques of cord-blood collection and electrophoretic investigation on both cellulose acetate and agar gel. These methods appear to give rapid, valid results at minimal expense and are well adapted to screening large populations (AU)

The in vivo sickle phenomenon: a reappraisal

Previous studies elsewhere have cast doubt on the in vivo relationship between oxygen saturation and red cell sickling. We have reinvestigated this relationship and find the expected correlation to occur at a variety of in vivo sampling sites. The correlation is apparent within data from single individuals, but may be lost when individual susceptibility to sickle cell formation is overlooked by pooling data from different patients. Samples from the hepatic vein did not usually fit the correlation and the unusual factors at this site are discussed (AU)

The irreversibly sickled cell: a determinant of haemolysis in sickle cell anaemia

Red cell survival was estimated in a group of adult sickle cell anaemia patients using the 51Cr technique. Counts of irreversibly sickled cells were performed on thin coverslip preparations of capillary blood. These counts are relatively constant within the same individual but show marked variations between individuals. A significant correlation has been demonstrated between the irreversibly sickled cell count and the red cell survival. This correlation does not apply to sickle cell anaemia patients with splenomegaly in whom the irreversibly sickled cell count is always low (AU)