5309 Introduction: β -Thalassaemia, an autosomal recessive hemoglobinopathy, is one of the commonest genetically transmitted disorders throughout the world. Collective measures including carrier identification, genetic counseling and prenatal diagnosis are required for preventing β -thalassemia. To achieve this objective, Identification of the spectrum of genetic mutations, especially for various ethnic backgrounds in Pakistan, since the country is a High Burdon Country. Therefore, we designed a cross sectional study to identify the frequency of various gene mutations in different ethnic groups of Pakistan. Methodology: Over a period of five years, venous blood samples were collected from 466 individuals belonging to different ethnic groups residing in Karachi, having at least one affected family member known to have β-thalassemia major/ HbE- β-thalassemia/ HbE homozygotes/ β-thalassemia trait. Chorionic villus sampling at 11 to 15 weeks gestational age for 143 couples referred by thalassemia clinics as also used to obtain allele information. In all, 648 mutated alleles were identified. The diagnosis of β-thalassemia trait, β-thalassemia major and Hb E thalassemia were established from clinical data, hematological indices and hemoglobin electrophoresis by cellulose acetate method. DNA was extracted from whole blood for detection of mutations. Primers were designed for simultaneous detection of the following previously described mutations in a single reaction: IVS 1–5 (G-C), Fr 8–9, IVS 1-1 (G-T), Cd-30 (G-C), Cd-5 (−CT), Del 619bp, Cd-15 (G-A), Fr 41–42, Fr 16 (−C) and Cap +1 (A-C) along with two Hb variants: HbS and HbE. Results: The genetic heterogeneity in Karachi is reflected by the identification of all the common β-thalassemia alleles and two Hb variants but following eight mutations were more common: IVS 1–5 (G-C), Fr 8–9, Del 619 bp, IVS 1-1 (G-T), Fr 41–42, Cd-30 (G-C), Cd-5 (−CT) and Cd-15 (G-A), accounting for 93.9% of the β-thalassemia alleles. However, the distribution was uneven. Although IVS 1–5 (G-C) was the most common mutation (40.89% of the sample), its frequency varied from 20% in the immigrant (from India) population to 76.9% in the Balochis. The second most frequent mutation was Fr 8–9, constituting 15.7% of the allele pool. Fr 8–9 was the most common mutation in the Pathans (31.3%) as it was in people of Saraikee origin (47%). Discussion: IVSI-5 (G-C),(40.89%), Fr8-9(15.7%), & IVSI-I(G-T),(8.17%), were the most common genetic mutations identified in Pakistan. Knowledge of the predominant mutation in a given ethnic group will not only help in developing a short panel of (population-specific) primers of mutations thereby providing a cost-effective method for prenatal diagnosis and also help the clinicians for genetic counseling and pregnancy termination. Disclosures: No relevant conflicts of interest to declare.
HU was found to be safe in patients with β-thalassemia major, and resulted in the reduction of transfusion requirement and in an increase in the interval between transfusions.
BACKGROUND:β -Thalassaemia, an autosomal recessive hemoglobinopathy, is one of the commonest genetically transmitted disorders throughout the world. Collective measures including carrier identification, genetic counseling and prenatal diagnosis are required for preventing β-thalassemia.Aim:To achieve this objective, Identification of the spectrum of genetic mutations, especially for various ethnic backgrounds in Pakistan. Therefore, we designed a cross sectional prospective study to identify the frequency of various gene mutations in different ethnic groups of Pakistan.MATERIALS AND METHODS:Over a 5-year period, DNA from 648 blood samples {including specimens of chorionic villus sampling (CVS)} were analyzed for the twelve most common β-thalassemia mutations found in the Pakistani population by a Multiplex amplification refractory mutation system (ARMS). Each sample was analyzed for the mutation as well as the normal gene, appropriate with negative and positive controls, and reagent blanks.RESULTS:Out of 648 samples mutations were identified in 640 (98.75%) samples by multiplex ARMS. 8 common β-thalassemia mutations were identified in 8 different ethnic groups accounting for 93.9% of the β-thalasemia alleles.CONCLUSIONS:Based on the outcome of this study a cost effective proposal is formulated for detection of β-thalassemia mutations.
β-thalassemia is characterized by impaired β-chain synthesis leading to ineffective erythropoiesis, severe anemia, and a need for blood transfusion. Presence of Xmn I polymorphism (-158 C-T nucleotide change) in γ-globin gene is associated with a higher fetal hemoglobin and a lesser clinical severity. This prospective study attempted to find out the effect of hydroxyurea (HU) on β-thalassemia patients in the presence or absence of Xmn I polymorphism. A total of 143 consecutive β-thalassemia patients received HU (16 mg/kg/d). Sixty-four (44.7%) had Xmn I polymorphism (either homozygous or heterozygous). Patients were evaluated at a median duration of 3 years (range, 6 mo to 9 y). Responders became transfusion independent after 6 months, partial responders had a least 50% reduction in transfusion requirement and nonresponders had no significant reduction. Of the 64 patients with Xmn I polymorphism, 44 (69%) showed response (P<0.01), whereas in those who lacked Xmn I polymorphism (n=79), only 17 (21%) were responders. This study showed that the presence of Xmn I polymorphism in β-thalassemia is a predictor of response to HU and highlights the possibility of managing this subset of patients without blood transfusion.
A small-for-date infant presented at birth with severe non-immune hydrops, cardiac failure, metabolic acidosis and hypoglycaemia. Ultrasonography disclosed a cardiomyopathy. Initial therapy consisting of artificial ventilation, inotropes and diuretics resulted in partial disappearance of oedema without significant improvement in cardiac function. Episodes of hypoglycaemia recurred despite continuous glucose infusions. Total serum carnitine from cord blood was 1.65 nmoles/ml and was undetectable on day 20. Oral DL-carnitine supplements resulted in normoglycaemia, dramatic improvement in cardiac function and restoration of serum carnitine levels to normal values. The infant was thereafter maintained on carnitine therapy. Follow-up over 1 year showed moderate growth retardation and normal developmental milestones. In order to account for such a severe neonatal presentation of carnitine deficiency, a combination of defective pre- and postnatal carnitine supply with an inborn error of carnitine handling is considered. The present case illustrates the need for evaluation of carnitine status in fetuses and neonates presenting with hydrops associated with cardiac failure.
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