RESUMEN
The objective of this study was to review the prevalence and features of the beta thalassaemia trait in Jamaican populations. Screening of 221,306 newborns over the last 46 years has given an indication of the distribution and prevalence of beta thalassaemia genes, and screening of 16,612 senior school students in Manchester parish, central Jamaica, has provided their haematological features. The prevalence of the beta thalassaemia trait predicted from double heterozygotes was 0.8% of 100,000 babies in Kingston, 0.9% of 121,306 newborns in southwest Jamaica, and 0.9% of school students in Manchester. Mild beta+ thalassaemia variants (-88 C>T, -29 A>G, -90 C>T, polyA T>C) accounted for 75% of Kingston newborns, 76% of newborns in southwest Jamaica, and 89% of Manchester students. Severe beta+ thalassaemia variants were uncommon. Betao thalassaemia variants occurred in 43 patients and resulted from 11 different variants of which the IVSII-849 A>G accounted for 25 (58%) subjects. Red cell indices in IVSII-781 C>G did not differ significantly from HbAA, and this is probably a harmless polymorphism rather than a form of beta+ thalassaemia; the removal of 6 cases in school screening had a minimal effect on the frequency of the beta thalassaemia trait. Red cell indices in the beta+ and betao thalassaemia traits followed established patterns, although both were associated with increased HbF levels. The benign nature of beta+ thalassaemia genes in Jamaica means that cases of sickle cell-beta+ thalassaemia are likely to be overlooked, and important clinical questions such as the role of pneumococcal prophylaxis remain to be answered.
RESUMEN
Based in the parish of Manchester in central Jamaica, the Manchester Project offered free detection of haemoglobin genotype to senior classes in 15 secondary schools between 2008 and 2013. Restricting the database to 15,103 students aged 15.0-19.9 years provided an opportunity to examine the red cell characteristics of the different haemoglobin genotypes, including normal (HbAA) in 85.0%, the sickle cell trait (HbAS) in 9.7%, HbC trait (HbAC) in 3.5% and hereditary persistence of foetal haemoglobin (HbA-HPFH) in 0.4%. Compared to the normal HbAA phenotype, HbAS had significantly increased mean cell haemoglobin concentration (MCHC), red cell count (RBC), and red cell distribution width (RDW) and decreased mean cell volume (MCV) and mean cell haemoglobin (MCH), these differences being even more marked in HbAC. Compared to HbAA, the HbA-HPFH had significantly increased RDW, but there were no consistent differences in other red cell indices, and there were no significant differences in haematological indices between the two common deletion HPFH variants, HPFH-1 and HPFH-2. Although these changes are unlikely to be clinically significant, they contribute to an understanding of the haematological spectrum of the common haemoglobin genotypes in peoples of African origin.
RESUMEN
To determine whether identifying haemoglobin genotype, and providing education and counselling to senior school students will influence their choice of partner and reduce the frequency of births with sickle cell disease. The Manchester Project provided free voluntary blood tests to determine haemoglobin genotype to the fifth and sixth forms (grades 11-13), median age of 16.7 years, of all 15 secondary schools in the parish of Manchester in south central Jamaica. A total of 16,636 students complied, and counselling was offered to carriers of abnormal genes over 6 years (2008-2013). The genotypes of their offspring were determined by newborn screening of 66,892 deliveries in 12 regional hospitals over 8 years (2008-2015). The study focused on the genotypes of live deliveries to female students with the four most common haemoglobin genotypes: 7905 with an AA genotype, 898 with the sickle cell trait, 326 with the HbC trait and 78 with the beta thalassaemia trait. A total of 2442 live deliveries were identified by the end of 2015 in mothers screened at school. Eleven babies had clinically significant genotypes, and the prevalence of SS and SC disease did not differ from that predicted by random mating. First pregnancy was not delayed in AS or AC mothers. There was no evidence that knowledge of maternal haemoglobin genotype influenced choice of partner. On an interview, mothers of affected babies correctly recalled their genotype, but either did not discuss this with their partners or the latter refused to be tested. Subjects delaying child bearing for tertiary education would be largely excluded from the present study of first pregnancies and may make greater use of this information. Future options are a greater role for prenatal diagnosis.
RESUMEN
The study aims to describe the logistics and results of a programme for newborn screening for sickle cell disease based on samples from the umbilical cord. Samples were dried on Guthrie cards and analysed by high pressure liquid chromatography. All suspected clinically significant abnormal genotypes were confirmed by age 4-6 weeks with family studies and then recruited to local sickle cell clinics. The programme has screened 66,833 samples with the sickle cell trait in 9.8 % and the HbC trait in 3.8 %. Sickle cell syndromes occurred in 407 babies (204 SS, 148 SC, 35 Sbeta+ thalassaemia, 6 Sbetao thalassaemia, 6 sickle cell-variants, 8 sickle cell-hereditary persistence of fetal haemoglobin) and HbC syndromes in 42 (22 CC, 14 Cbeta+ thalassaemia, 1 Cbetao thalassaemia, 5 HbC- hereditary persistence of fetal haemoglobin). Focusing on the year 2015, screening was performed in 15,408, compliance with sample collection was 98.1 %, and maternal contamination occurred in 335 (2.6 %) but in only 0.05 % did diagnostic confusion require patient recall and further tests. This model of newborn screening for sickle cell disease is accurate, robust and economic. It is hoped that it may be helpful for other societies with high prevalence of abnormal haemoglobins and limited resources, who are planning to embark on newborn screening for sickle cell disease.
RESUMEN
OBJECTIVES: To review the history of newborn screening for sickle cell disease with especial reference to Jamaica. METHODS: A summary was done of the history, the development of associated laboratory technology and the implementation of newborn screening for sickle cell disease in Jamaica. RESULTS: Screening was initiated at Victoria Jubilee Hospital, Kingston from 1973-1981, reactivated in 1995 and extended to the University Hospital of the West Indies in 1997 and to Spanish Town Hospital in 1998. From August 2008, there was a progressive recruitment of 12 hospitals in the south and west of Jamaica which has raised the frequency of islandwide newborn coverage from 25% in 1973 to 81%. The results of this extended programme in southwest Jamaica are presented. Dried blood spots collected from the umbilical cord proved stable, cheap and efficient; mean sample collection rates were 98%, maternal contamination occurred in < 1% and caused diagnostic confusion in < 0.1%. By March 31, 2015, a total of 54 566 births have been screened, detecting 161 with homozygous sickle cell (SS) disease, 125 with sickle cell-haemoglobin C (SC) disease and 36 with sickle cell-beta thalassaemia. Of the 327 babies with clinically significant sickle cell syndromes, all except five who died within seven days of birth were confirmed by four to six weeks and recruited to local sickle cell clinics. CONCLUSION: Early detection of sickle cell disease and recruitment to clinics is known to reduce its morbidity and mortality. The methods currently detailed provide an effective and economic model of newborn screening which may be of value elsewhere.
RESUMEN
OBJECTIVES: To raise awareness of significant iron deficiency anaemia occurring in Jamaican secondary school students. METHODS: Haematological screening of students in the fifth and sixth forms of 14 secondary schools in the parishes of Manchester and Clarendon, Jamaica, was done. Samples were subject to haemoglobin electrophoresis, examination of haematological indices, and haemoglobin, alpha 2 (HbA2) levels where indicated. RESULTS: Of 13 172 students with normal haemoglobin (AA) genotype aged 15-19 years, haemoglobin levels below 10 g/dL occurred in 0.36% of males and in 3.79% females. These subjects had low mean red cell volumes, low mean cell haemoglobin and high red cell distribution width, characteristic of iron deficiency, which was confirmed by dramatic increases in haemoglobin level following iron supplementation. Most revealed classic symptoms, histories of poor diets and pica, which generally resolved on iron supplementation. CONCLUSIONS: Iron deficiency, even in the absence of anaemia, is known to limit physical and mental functions and may impair intellectual performance in these high school students. Significant anaemia could be detected by incorporating a blood test into the school medical assessments performed on entry to secondary schools. There is a need for simple oral iron medications to be available at health centres.