The Spectrum of α-Thalassemia Mutations in Syrian Patients.

α-Thalassemia (α-thal) is a globally prevalent genetic disorder of hemoglobin (Hb) structure where the rate of α-globin chain synthesis is reduced or absent due to the presence of α-globin mutation(s). The aim of this study is to define the spectrum of α-globin gene mutations and evaluate their allele frequency in a group of α-thal carriers. A total of 55 individuals with possible α-thal patients were referred from the thalassemia centers in Syria. They have unexplained hypochromia and microcytosis. All patients were genetically tested for 21 common α-globin gene mutations using reverse hybridization kit. Seven different α-globin gene mutations and 13 different genotypes were detected in 55 patients. The two most frequently encountered mutations were -α3.7 deletion (47.1%) and --MED mutation (21.4%). The most commonly observed genotype was -α3.7/αα (40%), followed by --MED/αα genotype (21.8%). We determined the most common α thalassemia mutations in the Syrian patients. α-Thalassemia mutations with deletions were mostly observed in our study.

Compound heterozygosity for Hb C/Hb S (HBB: c.19G>A/HBB: c.20A>T) diseases observed in a Syrian family: a case report.

Hemoglobin S and Hemoglobin C disease is a type of sickle cell disease caused by two mutations at codon 6 of ß-globin gene. These mutations cause changes in the shape of the red blood cells. Little is known about its presence in our region. Case Presentation: The authors describe a case of a Syrian family consisting of father, mother, two daughters, and son. The mother presented with anemia, episodes of fatigue, and extreme pain (vaso-occlusive crisis). Beta and alpha-globin gene mutations have been analyzed using molecular detection methods. The results revealed that, the mother, second daughter, and son were all double heterozygous for hemoglobin C and S associated with the -α3.7 deletion mutation. The husband and the first daughter were found to have the hemoglobin C trait. Discussion: Hemoglobin (Hb) SC has been known to have a higher frequency in black populations and is restricted to persons of West African descent. In our case, all family members had dark brown skin color, and they were all diagnosed with Hb C or Hb SC. The mother, second daughter, and son had the clinical manifestations associated with Hb SC disease, and their values of mean cell volume and mean cell hemoglobin were low due to the presence of the -α3.7 deletion mutation. The husband and the first daughter do not have any serious health problems. Conclusions: To the best of the knowledge, this is the first case of compound heterozygous for hemoglobin C and S to be reported from a Syrian family.

A rare gene variation cap +1 (A>C) (HBB: c. -50A>C) associated with codon 5 (-CT) (HBB: c.17_18delCT) mutation in Syrian family.

BACKGROUND: CAP+1 [A>C] (HBB:c.-50A>C) is a rare silent ß-thalassemia (ß-thal) mutation. Carrier individuals of this mutation show borderline hemoglobin (Hb), mean corpuscular volume (MCV) and Hb A2 levels. This mutation was previously reported in combination with different ß-thalassemia mutations, leading to variable phenotypes. CASE PRESENTATION: Here, we describe for the first time the combination of silent CAP+1 [A>C] (HBB:c.-50A>C) mutation with ß0 codon 5 [-CT] (HBB:c.17_18delCT) mutation in a Syrian proband, leading to beta thalassemia intermedia (TI). CONCLUSIONS: The compound heterozygotes of the silent CAP+1 (A>C) together with another severe beta gene mutation, are phenotypically severe enough to present at an early age and require appropriate therapeutic modalities.

First Report on the Coinheritance of α-Thalassemia and a Rare ß-Thalassemia Compound Heterozygosity for the IVS-I-I(G>A)/IVS-II-705(T>G) Mutations in a Syrian Family.

We describe a proband originating from Al-Quneitra Province, Syria. His hematology data was as follows: Hb A 24.7%, Hb F 71.1%, Hb A2 4.2%. Molecular analysis, based on DNA sequencing of the ß-globin gene mutation, showed for the first time a compound heterozygous IVS-I-1 (G>A) (HBB: c.92+1G>A)/IVS-II-705 (T>G) (HBB: c.316-146T>G) on the ß-globin gene. A reverse hybridization technique revealed that the proband was also an α-thalassemia (α-thal) -α3.7 (rightward) deletion carrier. Haplotypes analysis for the seven polymorphic restriction sites showed that the compound heterozygous mutations, IVS-I-1/IVS-II-705, were linked to two haplotypes: I [+ - - - - + +] and VI [- + + - - - +], respectively. Our results showed, for the first time, the presence of rare ß-thalassemia (ß-thal) IVS-II-705 (T>G) mutation associated with IVS-I-1 (G>A). Our findings suggest the presence of these mutations resulted from past migrations.

Hb Knossos (HBB: c.82G > T), ß-globin CD 5 (-CT) (HBB: c.17_18delCT) and δ-globin CD 59 (-a) (HBD: c.179delA) mutations in a Syrian patient with ß-thalassemia intermedia.

BACKGROUND: Beta thalassemia (ß-thal) is an inherited hemoglobin disorder characterized by reduced synthesis of the hemoglobin that results in microcytic hypochromic anemia. ß-Thalassemia intermedia (TI) is a clinical term of intermediate gravity between the carrier state and ß-thalassemia major (ß -TM). CASE PRESENTATION: We describe a 12-year-old male proband originating from Al-Quneitra province - southwest Syria. Hematological investigations revealed, pallor and anemia (Hb 9 g/dl). The mean cell volume (MCV) 64 fL; mean cell hemoglobin (MCH) 21.8 pg. Capillary electrophoresis (CE) electropherogram revealed low level of Hb A1 (36.2%), high level of Hb F (62.2%) and low level of Hb A2 (1.6%). The proband requires blood transfusion occasionally. Direct DNA sequencing and Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) for mutations detection were used. The molecular analysis revealed the presence of rare ß+ Hb Knossos codon 27 (G > T) (HBB: c.82G > T) variant associated with ß0 codon 5 [-CT] (HBB: c.17_18delCT) mutation in beta-globin (ß-globin) gene and δ0 codon 59 [-A] (HBD: c.179delA) mutation in delta-globin (δ-globin) gene. The proband tested negative for the common deletional forms of alpha thalassemia (α-thal). Polymorphism of the Xmn-I locus (HBG2: c.-211C > T) revealed that the proband had a homozygous [TT] for Xmn-1 locus. CONCLUSIONS: To our knowledge, this is the first report of beta thalassemia intermedia due to combination of Hb Knossos /codon 5 [-CT] associated with δ0 codon 59 [-A] in Syrian patient. On the other hand, in Syria, ß-thal carriers who have low level of Hb A2 due to decreased δ-chain production, different δ-thal gene mutations must be screened to avoid the failure diagnosis of ß-thal disease.

Description of a Rare ß-Globin Gene Mutation: -86 (C>G) (HBB: c.-136C>G) Observed in a Syrian Family.

We present the description of a ß-thalassemia (ß-thal) -86 (C>G) (HBB: c.-136C>G) mutation in a Syrian family from Damascus, As-Suwayda Province, Syria, who was referred to the laboratory for prenatal diagnosis (PND). The mutation was found in the mother in a homozygous state, while it was in the father and in the amniotic fluid sample in a heterozygous state. This mutation is located at -86 within the proximal CACCC box in the promoter of the ß-globin gene and is possibly linked with a phenotype of ß+-thal. Polymerase chain reaction-restriction fragment length polymorphism (PCR/RFLP) analysis indicated that the -86 mutation was linked with haplotype I [+ - - - - + +]. We propose that Lebanon may be the origin of this mutation. To the best of our knowledge, this is the first report describing this mutation in As-Suwayda Province. These findings provide novel information on the region-specificity of this mutation in southwestern Syria.

Haplotype Analysis of Three Common ß-Thalassemia Mutations in Syrian Patients.

ß-Globin haplotypes were used to investigate the origin of three common ß-globin mutations, IVS-I-110 (G>A); HBB: c.93-21G>A, IVS-I-1 (G>A); HBB: c.92 + 1G>A and codon 39 (C>T); HBB: c.118C > T in Syrian patients. Haplotype analysis was done for 49 unrelated patients with ß-thalassemia (ß-thal) and 20 unrelated healthy subjects by polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) for the ß-globin gene cluster of the following polymorphic restriction sites: HincII 5' to ε, HindIII 5' to Gγ, HindIII 5' to Aγ, HincII in ψß, HincII 3' to ψß, AvaII in ß, and HinfI 3' to ß. The IVS-I-110 mutation was associated with three haplotypes: I [+ - - - - + +] (79.4%), V [+ - - - - + -] (5.9%) and VII [+ - - - - - +] (14.7%), while, the two mutations IVS-I-1 and codon 39 were be linked to a single haplotype V (100.0%) and II [- + + - + + +] (100.0%), respectively. The normal chromosomes (ßA/ßA) were associated with four haplotypes, I (50.0%), II (7.5%), V (32.5%) and VII (10.0%). In the Syrian population, the IVS-I-110 mutation was associated with multi haplotypes, whereas the IVS-I-1 and codon 39 mutations have a single origin. More studies for the other mutations will be very useful for genetic epidemiological studies in Syria.

Prenatal molecular diagnosis of ß-thalassemia and sickle cell anemia in the Syrian population.

Our objective was to evaluate the prenatal diagnosis (PND) of ß-thalassemia (ß-thal) and sickle cell anemia in Syria. Mutations detected from blood of at-risk couples and 55 amniotic fluid samples collected at the second trimester of pregnancy (14-22 weeks' gestation) were characterized. Molecular screening and direct DNA sequencing of the HBB gene was carried out. DNA analyses showed 14 affected fetuses (25.45%), 32 (58.18%) carriers and eight (14.54%) normal fetuses. It appears that 20.0% of individuals carried the sickle cell anemia mutation and 80.0% carried the ß-thal mutation. Thirteen different known mutations were detected in the fetuses. The most common mutations were: IVS-II-1 (G > A), codon 39 (C > T)], IVS-I-110 (G > A), IVS-I-1 (G > A) and IVS-I-5 (G > C). The Hb S [ß6(A3)Glu → Val; HBB: c.20A > T] mutation was the only abnormal hemoglobin (Hb) that was found. The results point to a successful future for PND of ß-thal and sickle cell anemia in Syria, using a rapid and accurate molecular method. We hope that this method will be used as a common application approach to decrease the incidence of ß-thal major (ß-TM).

Mutation spectrum of phenylketonuria in Syrian population: genotype-phenotype correlation.

Characterization of the molecular basis of phenylketonuria (PKU) in Syria has been accomplished through the analysis of 78 unrelated chromosomes from 39 Syrian patients with PKU. Phenylalanine hydroxylase (PAH) gene mutations have been analyzed by using molecular detection methods based on the restriction fragment length polymorphism (RFLP), artificial constructed restriction sites (ACRS) PCR and direct DNA sequencing. 56.4% of the patients had cPKU. A mutation detection rate of 79.49% was achieved and sixteen different mutations were found: missense 56.25%, splice site 37.5%, and frameshift 6.25%. The predominant mutation in this population sample was p.R261Q G>A, p.F55>Lfs and p.R243Q G>A. No mutation in six PKU patients was observed. In 57.9% of patient genotypes, the metabolic phenotype could be predicted. The identification of the mutations in the PAH gene and the genotype-phenotype correlation should facilitate the evaluation of metabolic phenotypes, diagnosis, implementation of optimal dietary therapy, and determination of prognosis in the patients and genetic counseling for the patient's relatives.