Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The majority of a-thalassemia results from the large deletions in a-globin gene cluster, including both or either one of alpha-globin genes (alpha1 and alpha2). Most common a-thalassemia-2 deletions (single gene deletions) are -alpha3.7 and -alpha4.2, and alpha-thalassemia-1 deletions (double gene deletions) are --SEA, --THAI, --FIL, --MED and -(alpha)20.5 Although it is not easy to diagnose these deletions because of the high GC content at this locus and the sequence homology among psi alpha2, psi alpha1, alpha2 and alpha1 genes, these alleles can now be diagnosed by a single tube multiplex gapPCR assay. We showed here two Saudi Arabian patients with a-thalassemia trait who could be determined their gene mutations according to the method of Chong SS et al. (2000). [Case 1: 21-year-old male] GapPCR assay revealed the amplification of only -alpha3.7, whereas PCR of both a-globin genes showed no amplifications. The results indicate case 1 is a homozygote of -alpha3.7(-alpha3.7/-alpha3.7). [Case 2: 31-year-old male] GapPCR assay revealed the amplification of only -alpha3.7, and PCR of both alpha globin genes showed normal amplification. DNA sequencing of the amplified a-globin genes revealed a point mutation in the poly A site of alpha2-globin gene (AATAAA-->AATAAG), which is known as alpha(T-Saudi). Thus, case 2 was confirmed to be a compound heterozygote of -alpha3.7 and alpha(T-Saudia) alpha(-alpha3.7 / alpha(T-Saudi) alpha). This gapPCR assay is a rapid, reliable screening test for common alpha-thalassemia deletions and seems to be useful for the diagnosis of thalassemic patients without an increase of Hb A2 and/or an abnormality of beta-globin gene.
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PMID:[Genetic screening for alpha-thalassemia deletional determinants by GapPCR method]. 1724 Aug 29

In this study, 32 patients with Hb H (beta(4)) disease have been identified. Three different alpha-thalassemia-1 (thal) determinants; nine with the -17.4 kb (MED I) type, 12 with the -20.5 kb type and 10 with the -26.5 kb (MED II) type were characterized. Of the 32 patients, 19 had the 3.7 kb deletion and one had the 4.2 kb deletion in trans to alpha-thal-1 determinants. Only one patient, homozygous for the polyadenylation signal (poly A) site (PA 1) mutation, was identified to be associated with Hb H disease. The other patient had the poly A (PA 1) mutation in trans to the MED I (-17.4 kb) determinant. The 5 nt (nucleotide) deletion was present in three patients, two of them in the same family; this mutation was found in association with the MED II (26.5 kb deletion). The other patient had the -5 nt mutation in trans to the MED I (-17.4 kb) determinant. An unstable hemoglobin (Hb) variant [Hb Adana, codon 59 (CA)] was present in association with the alpha-thal-1 deletion (20.5 kb) in two adults and caused a severe type of Hb H disease. Five patients with Hb H disease had the genotype - -(MED II)/alpha(PA 2)alpha one had a Hb S heterozygosity (- -(MED II)/alpha(PA 2)alpha + Hb AS). A patient with Hb H disease (- -(MED I)/-alpha(3.7)) also had Hb S trait.
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PMID:Hb H (beta4) disease in Cukurova, Southern Turkey. 1748 10

Antenatal sickle and thalassaemia screening programmes are now established in most high prevalence areas in England. Although screening reliably detects beta-thalassaemia trait, in many cases, results state that alpha-thalassaemia trait cannot be excluded. The detection of couples at risk of a child with hydrops fetalis is one of the aims of the national programme. We, therefore, performed polymerase chain reaction (PCR) for the common alpha-thalassaemia gene deletions to assess the usefulness of this technique in routine screening practice. Between August 2001 and August 2002, of the 5092 women booked at the antenatal clinic, 425 were found to have a mean corpuscular haemoglobin (MCH) <27 pg in the absence of beta-thalassaemia trait; 189 (44.5%) had an MCH <25 pg. All 425 patients underwent PCR analysis for the common deletions: -SEA (South-East Asian), -MED (Mediterranean), -alpha(20.5), -FIL (Filipino), -alpha 3.7 and -alpha 4.2 genotypes. In total, 130 (31%) women were positive for alpha-thalassaemia deletion; 86 (24.7%) were heterozygous for -alpha 3.7, 19 (4.4%) were homozygous for -alpha 3.7, 12 (2.8%) were heterozygous for -alpha 4.2, 1 (0.2%) was homozygous for -alpha 4.2, 11 (2.6%) were heterozygous for -SEA and one (0.2%) was heterozygous for the -MED genotype. Although the detection rate for alpha(+)-thalassaemia was high, a strategy of selective screening using MCH <25 pg and ethnic group (SEA, Middle East or Eastern MED) would have identified all individuals heterozygous for alpha(0)-thalassaemia. Routine molecular screening for all forms of alpha-thalassaemia trait is unjustified in antenatal screening.
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PMID:Is routine molecular screening for common alpha-thalassaemia deletions necessary as part of an antenatal screening programme? 1841 56

An epidemiological molecular study was carried out to evaluate the spectrum and allelic frequency of alpha-thalassemia (alpha-thal) defects in Algeria. A series of 153 randomly selected blood donors was screened for 10 alpha-thal alleles described in the Mediterranean area. In addition, six unrelated cases with hematological and biochemical data suggestive of Hb H disease were investigated. Our data revealed an allele frequency of 4.6%. The presence of alpha(0)-thal determinants (-alpha(20.5) and --MED I) was observed both in Hb H patients and in the randomly collected samples. Overall, the -alpha(3.7) deletion was the most prevalent allele (2.9%), followed by the alpha(Nco I)alpha (HBA2:c.1A>G) allele (0.6%) and by the alpha(Hph I)alpha (HBA2:c.95 + 2_95 + 6delTGAGG), -alpha(20.5), --(MED I) alleles (0.3% each). The -alpha(4.2) deletion was observed in only one Hb H patient. These results outline the heterogeneity of the alpha-thal alleles in Algeria which reflects the anthropological history of the country. Because of their frequency, alpha-thal alleles are probably frequent modulators of prevalent beta-globin gene-related hemoglobinopathies in Algeria.
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PMID:Molecular basis of alpha-thalassemia in Algeria. 1847 43

To improve the differentiation of thalassemia intermedia from other hemoglobinopathies in Iran, four known genetic mechanisms-XmnI (G)gamma polymorphism, inheritance of mild and silent beta-thalassemia alleles, delta beta deletion, and coinheritance of alpha- and beta-thalassemia-were investigated in 52 Iranian individuals suspected to have thalassemia intermedia based on clinical and hematological characteristics. Beta-globin mutations were studied using a reverse-hybridization assay and sequencing of the total beta-globin gene. The XmnI (G)gamma polymorphism, the Sicilian delta beta deletion, and four alpha-globin mutations (-a(3.7), -a(4.2), -(MED), aaa(anti-3.7)) were studied using PCR-based techniques. The inheritance of the XmnI (G)gamma polymorphism with severe beta-thalassemia alleles in the homozygous or compound heterozygous state was the predominant mechanism observed in 27 individuals (55.3%). In five cases, this status overlapped with the -a(3.7)/aa genotype. The second most frequent cause for thalassemia intermedia (14.8%) was the inheritance of mild beta-thalassemia alleles, including IVS-I-6 (T > C), -88 (C > A), and + 113 (A > G). In three subjects (4.3%) the Sicilian delta beta deletion was identified. HbS in association with beta-zero-thalassemia was found in three patients with thalassemia intermedia phenotype. In 11 cases (21.3%) no causative genetic alteration could be identified. Our results reflect the diversity underlying thalassemia intermedia, and the limitations of the applied clinical, hematological, and molecular approaches for correct diagnosis. Some of the unresolved cases will offer an opportunity to discover additional molecular mechanisms leading to thalassemia intermedia.
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PMID:Molecular mechanisms underlying thalassemia intermedia in Iran. 1893 39

Although alpha-thalassemia (alpha-thal) is the most common hereditary hemoglobin (Hb) disorder in Iran, no comprehensive data are so far available on the prevalence of the disease in the province of Khuzestan in Southwest Iran. This study investigates the spectrum of alpha-thal mutations in this region. One hundred and twenty-one subjects from Khuzestan Province, Iran, were initially tested for the three most common Iranian alpha-thal mutations (- alpha3.7, -alpha4.2, and --MED) by gap-polymerase chain reaction (gap-PCR). Reverse hybridization test strips and DNA sequencing were used to identify additional alpha-globin mutations. A total of 131 mutated alpha-globin alleles were identified in these patients. Of the 13 mutations that were detected in Khuzestan Province, Iran, the - alpha3.7 single gene deletion was the most frequently identified variant, representing 62.6% of the total; we also observed significant numbers of individuals with compound heterozygous mutations. On the basis of our results, we strongly recommend screening for the most common mutations to improve the molecular diagnosis of anemia in this region.
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PMID:alpha-thalassemia mutations in Khuzestan Province, Southwest Iran. 1906 32

The definitive diagnosis of alpha-thalassemia involves detection of a deletion of one or more alpha-globin that encode the alpha-chains of Hb (hemoglobin). To determine whether DNA analysis is indicated, screening tests such as mean corpuscular volume (MCV) and Hb typing are employed. alpha-Thalassemia often correlates with normal or low HbA2 values. Zinc protoporphyrin (ZPP) is usually high in ferropenic anemia or lead-poisoning and is normal or slightly raised in beta-thalassemia. Therefore, ZPP is currently used as a marker to discriminate between ferropenic anemia and beta-thalassemia. We investigated the diagnostic potential of ZPP < 150 micromol/mol heme in a screening strategy for alpha-thalassemia. We measured ZPP and performed DNA analysis for detecting the seven most prevalent alpha-thalassemia deletions, namely, alpha3.7, SEA, alpha20.5, alpha4.2, MED, FIL, and THAI, in the blood samples of 200 patients with MCV < 70 fL and HbA2 < or = 3.5%. Deletions were detected in 9% subjects in the ZPP > or = 150 group (n = 175) and 56% subjects in the ZPP < 150 group (n = 29); this difference was statistically significant (chi-square test, P < 0.001). We conclude that ZPP < 150 micromol/mol heme can be used in a new screening strategy for alpha-thalassemia.
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PMID:Diagnostic value of zinc protoporphyrin in a screening strategy for alpha-thalassemia. 1918 79

The molecular basis of alpha-thalassemia (alpha-thal) has been addressed by several studies from the eastern Mediterranean region, but not from Iraq. To address this issue, we studied 51 individuals with unexplained hypochromia and/or microcytosis, as well as nine patients with documented Hb H disease from the Dohuk region in northern Iraq. We used multiplex gap-polymerase chain reaction (gap-PCR), reverse hybridization, and sequencing for this purpose. It was found that the most common genotypes in those with unexplained hypochromia and/or microcytosis were -alpha(3.7)/alpha alpha, followed by - -(MED-I)/alpha alpha, then -alpha(3.7)/-alpha (3.7), respectively, detected in 84.3% of the above individuals. Other genotypes identified sporadically were -alpha(4.2)/alpha alpha, alpha(poly A1)alpha/alpha alpha (AATAAA>AATAAG), alpha(Adana)alpha/alpha alpha [Hb Adana, codon 59 (Gly-->Asp) or HBA1:c.179G>A], and alpha(Evanston)alpha/alpha alpha [Hb Evanston, codon 14 (Trp-->Arg) or HBA1:c.43 T>C]. Three cases (5.88%) remained uncharacterized even after sequencing. All nine Hb H cases carried the -alpha(3.7)/- -(MED-I) genotype. Such findings are rather different from those in other eastern Mediterranean populations, particularly with relevance to an Hb H molecular basis.
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PMID:Molecular characterization of alpha-thalassemia in the Dohuk region of Iraq. 1920 71

Two hundred and fifty-five patients from Mazandaran Province, Iran, all presenting with hypochromic and microcytic anemia, were selected for alpha-thalassemia (alpha-thal) mutation screening. We detected a total of 274 alpha-globin mutations in 227 (89%) of these patients. Among the 21 different alpha-globin alleles found, the -alpha(3.7) (44.9%), polyadenylation signal 2 (poly A2) (AATAAA>AATGAA) (18.2%), -alpha(4.2) (9.1%), alpha(IVS-I(-5 nt)) (6.5%), - -(MED) (4.3%), and alpha(codon 19 (-G)) (4%) were the most frequent. The other 15 mutations included variants that had not yet been observed in Iran, such as Hb Bleuland [alpha108(G15)ThrAsn, ACC>AAC (alpha2)], as well as a novel mutation on the alpha2 gene, also not described to date [3 ' untranslated region (3 'UTR) nucleotide (nt) 46 (C>A)]. These comprehensive new data are useful for establishing a screening strategy for the effective control of alpha-thal in Mazandaran Province.
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PMID:alpha-Thalassemia mutation analyses in Mazandaran province, North Iran. 1937 87

One hundred and three patients from Gilan Province, Iran, presenting with hypochromic and microcytic anemia parameters without iron deficiency were included in this study. Using gap-polymerase chain reaction (gap-PCR), reverse hybridization StripAssay and DNA sequencing, we detected a total of 113 alpha-globin mutations in 94 (91.3%) of these patients. Most prevalent of the 16 different alpha-thalassemia (alpha-thal) alleles was -alpha(3.7) (42.5%), followed by the polyadenylation signal (poly A2) (AATAAA>AATGAA) (12.4%), Hb Constant Spring [Hb CS, alpha142, Term-->Gln (TAA>CAA in alpha2] (10.6%), --(MED) (8.8%), IVS-I donor site [GAG GTG AGG>GAG G-----, alpha(-5 nt) (-TGAGG)] (7.1%), -alpha(4.2) (4.4%) and poly A1 (AATAAA>AATAAG) (3.5%). An additional nine mutations were observed at frequencies below 2%. We also found two novel alpha1 gene mutations: alpha(-9) (HBA1: c.-9 G>C) and alpha(IVS-I-4) (HBA1: c.95+4 A>G). Our new findings will be valuable for improving targeted thalassemia screening and prevention strategies in this area.
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PMID:Alpha-thalassemia mutations in Gilan Province, North Iran. 1965 38


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