Hemoglobin S (HbS, α2β26GluVal) merupakan variasi hemoglobin yang terbentuk hasil daripada mutasi GAG GTG pada kodon 6 gen β-globin. Hemoglobinopati haemoglobin S (HbS) jarang ditemui di kalangan penduduk Malaysia tetapi selalunya dijumpai di kalangan pendatang asing dari Afrika. Walau bagaimanapun beberapa kes didapati dalam kaum India dan Melayu. Kajian ini meninjau keputusan makmal pesakit HbS dan penggunaan “multiplex ligation-dependent probe amplification” (MLPA) dan “flow-through hybridization” (FTH) dalam mengesan mutasi HbS. HbS dikenalpasti melalui kromatografi cecair prestasi tinggi (HPLC) dan/atau elektroforesis kapilari serta elektroforesis hemoglobin. Analisis molekul dijalankan menggunakan kaedah MLPA, FTH dan penjujukan Sanger. Dua warga Afrika, tiga Melayu dan dua India berusia antara 2-31 tahun telah dikenalpasti. Lima pesakit adalah HbS homozigot, seorang kompaun heterozigot HbS/β-talasemia dan seorang lagi pembawa HbS. Tahap hemoglobin (Hb) kes HbS homozigot adalah antara 7.4-10.2 g/dL dengan aras HbS dan HbF diantara 58.3-94.7% dan 1.5-35.5%. Hb untuk kes kompaun heterozigot HbS/β-talasemia adalah 5.8 g/dL dan normal pada pembawa HbS. Aras HbS, HbF dan HbA2 untuk HbS/β-talasemia dan pembawa HbS adalah 67%, 27.2% dan 4.2%, dan 38.6%, 0.1% and 2.8% setiap satu. Kedua-dua kaedah MLPA dan FTH berjaya mengesan mutasi HbS dalam semua kes, manakala cuma FTH dapat menentukan zygositi mutasi HbS dan β-talasemia dalam satu ujian yang sama.
Sickle cell disease (SCD) is an inherited red cell disorder, characterized by the tendency of haemoglobin S or sickle haemoglobin to polymerize and assume a characteristic sickle shape. Molecular analysis has been the mainstay of detection method when confirmation is required. Previously a polymerase chain reaction (PCR)-based restriction enzyme analysis was used for this purpose. A simple bidirectional allele-specific amplification, recently described by Waterfall in 2001 was used to detect the GAG --> GTG mutation on codon 6 of the beta globin gene. Two sets of primers for the mutant and the wild type alleles were used in a single PCR reaction to amplify the regions of interest. The resultant PCR products will produce two fragments at 517 and 267 base pair (bp) respectively. This report highlights the investigations for SCD in the family of a 16-year old girl with recurrent painful crisis affecting the lower limbs whereby the family members are asymptomatic for the disease. Her haemoglobin electrophoresis at an alkaline pH showed dense bands at the HbS and HbF regions, while her father and two sisters had bands at HbS, HbF and HbA. The PCR analysis showed that she was homozygous for the mutation by the presence of only one band at 267 bp fragment, while the father and her sisters were heterozygotes, with the presence of two bands at 267 as well as 517 bp fragments. DNA sequencing of the sample confirmed the mutation. In conclusion, this case report highlighted the simple and cheap yet practical method for molecular confirmation of the presence of HbS gene in subjects with homozygous or heterozygous state of the condition.
Haemoglobin S D-Punjab is a rare compound heterozygous haemoglobinopathy characterised by the presence of two β globin gene variants: Β6(GAG→GTG) and Β121(GAA→CAA). These patients' clinical and haematological features mimic haemoglobin S disease. We describe the first case of doubly heterozygous HbSD-Punjab from Malaysia managed with regular blood transfusion at the age of one. This case highlights the propensity for occurrence of rare phenotypes within our multi-ethnic population and emphasises the importance of accurate genotyping to avoid erroneous counselling, and to plan an effective patient management strategy before complication evolves.
Clinical manifestations of sickle cell disease (SCD) arise from the tendency of the sickle haemoglobin to polymerize and deform red blood cells into the characteristic sickle shape. Sickle cell crisis is a devastating complication that may occur in patients with SCD. If not managed properly permanent organ damage and even death may be the final outcome. A case of a 32-year-old Nigerian lady, Gravida 1 Para 0 in her first trimester, with SCD who developed signs and symptoms of delayed haemolytic transfusion reaction after receiving packed red cell transfusion is demonstrated. Multiple red cell alloantibodies were detected in the patient's plasma; anti-Fy a, anti-Jk b and anti-E. The patient miscarriaged and succumbed to complications of hyperhaemolysis with delayed haemolytic transfusion reaction, acute chest syndrome and renal failure. There is an urgent need for mandatory red cell antibody screen and identification especially in high-risk cases. Prevention of alloimmunization by supplying phenotype-specific red cells is also required.
Clinical studies were carried out on mild Indian sickle cell anaemia in Malaysia, and genetic and fertility studies were carried out on 101 families with and without sickle-cell haemoglobin (Hb S). The Indian sickle cell anaemia patients reached adulthood, and pregnancies and deliveries were uneventful without blood transfusion. There was no foetal wastage and the number of children produced was not significantly different from that in families without Hb S. 28 Indian patients hospitalized with Plasmodium falciparum malaria infection were also examined for their beta S genotype. P. falciparum malaria infection occurred much more frequently in individuals without Hb S than in Hb S carriers.
The Indian rubber estate workers in Negri Sembilan, Malaysia, who originated from Orissa in India were found to have a high frequency of Hb S (Joishy SK, Hassan K: Clin Res 28:280, 1980). Unlike the usually severe clinical picture of sickle cell anemia seen in African and American blacks, the clinical picture of the disease in this population was mild and many have reached old age. We studied the leukocyte DNA of 12 patients with sickle cell anemia, ranging in age from 4 to 61 years and 30 sickle cell trait carriers, ranging in age from 7 to 63 years, for the presence of alpha-globin gene deletions by gene mapping according to Southern (Southern EM: J Mol Biol 98:503, 1975), using alpha- and zeta-globin gene probes obtained by nick translation of the alpha- and zeta-globin genes cloned into plasmid. All 12 sickle cell anemia patients were found to have alpha-thalassemia2 (alpha-thal2), either in the homozygous or heterozygous condition. Of the Hb S trait carriers, six did not have alpha-thal2 or alpha-thal1 and 24 had alpha-thal2 (15 heterozygous, 9 homozygous). Seven of these Hb S trait carriers with alpha-thal2 had an additional gene abnormality. Five of them had a fast-moving Eco RI fragment 5.6 kb long that hybridized with zeta-specific probe but not with alpha-specific probe. An unusual DNA pattern of a different type was further found in the other two. Bgl II restriction analysis showed that the alpha-thal2 was mostly of the rightward deletion alpha-thal1 genotype. None of the sickle cell anemia patients and Hb S trait carriers had deletion type alpha-thal1. The sickle cell anemia patients had very high levels of Hb F and low levels of Hb A2. The Hb S trait carriers with alpha-thal2 had relatively low levels of Hb S.
Four cases of Hb S were seen between Jan. 1976 and June 1976; three of them were newly discovered while the fourth was previously diagnosed. Out of the four cases, two were Malays and the other Indians. The family members of one Malay case were investigated. Six members had Hb S and three had Hb CoSp. Association of Hb CoSp and Hb S was seen in two of the members. Clinically they were healthy.
We have systematically analyzed beta-thalassemia genes using polymerase chain reaction-related techniques, dot-blot hybridization with oligonucleotide probes, allele specific-polymerase chain reaction, and sequencing of amplified DNA fragments from 41 unrelated patients, including 37 beta-thalassemia homozygotes, three with beta-thalassemia/Hb E, and one with beta-thalassemia/Hb S. Four different beta-thalassemia mutations were detected in 78 alleles. These are the IVS-I-5 (G-->C), codon 30 (AGG-->ACG) [also indicated as IVS-I (-1)], IVS-I-1 (G-->A), and codons 41/42 (-TTCT) mutations. The distribution of the beta-thalassemia mutations in the Maldives is 58 alleles (74.3%) with the IVS-I-5 (G-->C) mutation, 12 (15.4%) with the codon 30 (AGG-->ACG) mutation, seven (9%) with the IVS-I-1 (G-->A) mutation, and one with the codons 41/42 (-TTCT) mutation. The first three mutations account for 98.7% of the total number of beta-thalassemia chromosomes studied. These mutations are clustered in the region spanning 6 bp around the junction of exon 1 and the first intervening sequence of the beta-globin gene. These observations have significant implications for setting up a thalassemia prevention and control program in the Maldives. Analysis of haplotypes and frameworks of chromosomes bearing each beta-thalassemia mutation suggested that the origin and spread of these mutations were reflected by the historical record.