Jamaican Sbetañthalassaemia: mutations and haematology

The sickling disorders are a common cause of morbidity and mortality in Jamaica. Sickle cell betañthalassaemia is the fourth commonest form, occuring in one in every 3000 births. This is a heterogeneous condition, producing HbS, HbF and HbA2 with variable amounts of HbA, depending on the mutation and, within a defined population, only a few beta-thalassaemia mutations occur at high frequency. This study establishes the frequency of beta-thalassaemia mutations in Sbetañthalassaemia patients in Jamaica. In addition, comparison of the haematological phenotypes is possible by looking at the "average steady-state haematology" of the different mutational groups. Blood samples from 132 unrelated Sbetañthalassaemia patients attending the MRC Sickle Cell Unit at the University of the West Indies were analysed by amplification refractory mutation system (ARMS) polymerase chain reaction (PCR) or sequencing to determine the nature and frequencies of the underlying beta-thalassaemia mutations. Ten mutations were identified, four of which accounted for 93 percent of the patients studied. These were 29 (A --> G) in 71 (54 percent), -88 (C --> T) in 27 (20 percent), polyA (T --> C) in 17 (13 percent) and IVS1-5 (G --> C) in nine (7 percent). The six remaining mutations found at lower frequency were C24 (T --> A) in two patients and one each of IVS2-848 (C --> A), -90 (C --> T), IVS1-5 (G --> T),IVS1-6 (T --> C). In one individual, no mutation was found. The three commonest mutations were all associated with levels of greater than 10 g/dl, whereas IVS1-5 (G --> C) had a more severe haematological phenotype. The predominance of -29 (A --> G) and -88 (C --> T) is in keeping with other studies on populations of African origin. IVS1-5 (G --> C) is found chiefly in Indian populations, and all affected families acknowledged Indian ancestry, reflecting the prominent Indian community in Jamaica. (AU)

Quality of life in children with sickle cell disease in Amsterdam area

OBJECTIVE: To determine the differences in quality of life between children with sickle cell disease and healthy immigrant children. DESIGN: Descriptive, comparative. METHOD: The quality of life of children with sickle cell disease between 5 and 15 years old being treated in the Emma Children's Hospital AMC in Amsterdam, the Netherlands, was assessed by using a questionnaire for parents (TNO-AZL Children's Quality of Life Questionnaire (TACQOL) parent form) if the child was between 8 and 15 years old. The study period was April-October 1998. The questionnaires were completed by 45 (parents of) patients. The results were compared with a healthy reference group of immigrant children. Statistical analysis was performed using the Student t-Test. RESULTS: Children with sickle cell disease as well as their parents scored signifcantly lower on the items general physical, motor and independent daily functioning and on occurrence of negative emotions. No significance was observed for the items cognitive functioning and school performance nor for social functioning or occurrence of positive emotions. CONCLUSIONS: In children, sickle cell disease leads to compromised physical and possibly also psychological wellbeing, as well as the experience of decreased independence in daily functioning, but not to compromised cognitive or social aspects of the quality of life. (AU)

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)

Biliary sludge in sickle cell disease

Biliary sludge was observed in the gallbladder in 17 of 429 patients in a cohort study of sickle cell disease. Discrete gallstones later developed in 12 patients, but no stones developed in five patients; one patient with biliary sludge had no change in his condition for 5 years. None of the patients with biliary sludge had any symptoms referable to the biliary tract, and cholecystectomy has not been performed. The Jamaican experience suggests that biliary sludge may be treated conservatively, similar to our approach to asymptomatic gallstone. (AU)

Sá+ thalassaemia in Jamaica: haematological comparison of the three commonest á+ thalassaemia mutations

A study of the á-thalassaemia mutations by amplification refractory mutation system (ARMS) PCR of 130 Sá+ thalassaemia patients attending the sickle-cell clinic at the University of the West Indies revealed that 70 (53.9 percent) had the -29 (A to G) mutation, 23 (17.7 percent) had -88 (C to T), 19 (14.6 percent) had Poly A(AATAAA to AACAAA) and 2(1.5 percent) had C24 (T to A). In 16 (12.3 percent) patients we were unable to identify the mutations with the available primers. Of the three major groups, the -88 group had a higher foetal haemoglobin (HbF) than the -29 groups, who in turn had a higher haemoglobin (p<0.001). The -88 and -29 groups had a higher haemoglobin (p<0.01), a higher corrected haemoglobin A2(p<0.001), a higher calculated cell volume (p<0.001), a higher packed cell volume (p<0.01) and a higher mean cell volume (p<0.05) than the Poly A group. The -29 group also had fewer reticulocytes than the Poly A group (p<0.001). The difference in HbF levels could be a consequence of the thalassaemia mutations affecting the interaction of the á-globin gene to differing extents (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)

Molecular characterization of á-thalassaemia mutations in Guadeloupe - abstract

In order to delineate the spectrum of á-thalassaemia (á-thal) mutations in the Guadeloupean population, we have analysed a representative sample of 59 unrelated families carrying a á-thalassaemia trait. Using gene amplification, hybridization with 32P-labelled oligonucleotide probes and sequencing of amplified DNA, 8 different á-thal mutations were identified in 62 members of 36 families. Four of these families carried a á§-thal trait whereas, in the 32 others, a á+-thal trait has been identified. All patients were á-thal heterozygous: 30 had Hb S/á-thal, 1 had Hb C/á-thal, 1 had HPFH/á-thal whereas the remaining 30 had a Hb A/á-thal genotype. Four of the á-thal mutations detected [-29 (A -> G), IVS-I-5 (G -> C), IVS-II-1 (G -> A) and CD 24 (T -> A)] accounted for approximately 88.8 percent of the á-thalassaemia chromosomes identified. The four other variants, -88 (C -> T), IVS-I-5 (G -> A), IVS-I-5 (G -> T) and IVS-I-2 (T -> C), are less frequent. The á-thalassaemia mutations in 23 families remained unidentified and are under investigation. This study provides data for prenatal diagnosis of sickle-cell disease for Hb S/á-thalassaemia genotypes (AU)