A case with α-thalassemia caused by novel start codon variant in conjunct with right deletion variant of α2-globin gene / 中华医学遗传学杂志

OBJECTIVE@#The explore the genetic basis for a patient with microcytic hypochromic anemia and iron deficiency anemia.@*METHODS@#Common deletions and variants of the globin genes were detected by Gap-PCR and next generation sequencing (NGS). Suspected mutations were verified by Sanger sequencing.@*RESULTS@#Gap-PCR and NGS showed that the proband has carried a αα/-α @*CONCLUSION@#Patients with α HBA2 c.2T>A(p.Met1Lys) α/-α

Regulación de expresión de genes de la familia de ß-globina humana, útil en la búsqueda de nuevos blancos terapéuticos para tratamiento de hemoglobinopatías / Regulation of the ß-globin gene family expression, useful in the search for new therapeutic targets for hemoglobinopathies

Durante la etapa embrionaria, el desarrollo fetal y la vida posnatal se expresan isoformas funcionalmente distintas de hemoglobina, producto de la combinación de cadenas polipeptídicas sintetizadas a partir de los distintos genes que componen las familias de α- y β-globina. En función de que la presencia de altos niveles de hemoglobina fetal (Hb F) es beneficiosa en síndromes falciformes y talasémicos graves, se plantea revisar las bases de la regulación de la expresión de los genes de la familia de β-globina, en particular los genes que codifican las cadenas de γ-globina (HBG1 y HBG2). En este trabajo se revisan los conocimientos sobre factores de transcripción y reguladores epigenéticos que gobiernan los eventos de encendido y apagado de los genes de la familia de β-globina. Se espera que la consolidación de estos conocimientos permita hallar nuevos blancos terapéuticos para el tratamiento de hemoglobinopatías.

Different hemoglobin isoforms are expressed during the embryonic, fetal and postnatal stages. They are formed by combination of polypeptide chains synthesized from the α- and β- globin gene clusters. Based on the fact that the presence of high hemoglobin F levels is beneficial in both sickle cell disease and severe thalassemic syndromes, a revision of the regulation of the β-globin cluster expression is proposed, especially regarding the genes encoding the γ-globin chains (HBG1 and HBG2). In this review we describe the current knowledge about transcription factors and epigenetic regulators involved in the switches of the β-globin cluster. It is expected that the consolidation of knowledge in this field will allow finding new therapeutic targets for the treatment of hemoglobinopathies.

Hemoglobin Fontainebleau [a21(B2)Ala>Pro]: The second report from India.

Structural hemoglobin (Hb) variants are mainly due to point mutations in the globin genes resulting in single amino acid substitutions. Until date, about 200 alpha chain variants have been identified and they are usually detected during the hemoglobinopathy screening programs. Under a community control program for hemoglobinopathies, which involved screening of antenatal cases followed by prenatal diagnosis if indicated. Here, we report a rare alpha globin gene variant Hb Fontainebleau [a21(B2)Ala>Pro] detected in the heterozygous condition in a 35‑year‑old pregnant lady screened during this program. This is the second report of this alpha globin variant from India. Unlike the earlier case from India where Hb Fontainebleau was reported in a neonate who was also a carrier of Hb Sickle and had no clinical problems, this case presented with a bad obstetric history associated with the secondary infertility. However, the presence of the variant and the obstetric complications may be unrelated.

Clinical Characteristics of Pediatric Thalassemia in Korea: A Single Institute Experience

Few literatures have elaborated on the clinical characteristics of children with thalassemia from low-prevalence areas. A retrospective analysis was conducted on children genetically confirmed with thalassemia at Seoul National University Children's Hospital in Korea. Nine children (1alpha thalassemia trait, 6beta thalassemia minor, 2beta thalassemia intermedia) were diagnosed with thalassemia at median age of 4.3 yr old with median hemoglobin of 9.7 g/dL. Seven (78%) children were incidentally found to be anemic and only 2 with beta thalassemia intermedia had presenting symptoms. Five children (56%) were initially misdiagnosed with iron deficiency anemia. Despite the comorbidities due to alpha thalassemia mental retardation syndrome, the child with alpha thalassemia trait had mild hematologic profile. Children with beta thalassemia intermedia had the worst phenotypes due to dominantly inherited mutations. None of the children was transfusion dependent and most of them had no complications associated with thalassemia. Only 1 child (11%) with codon 60 (T-->A) mutation of the HBB gene needed red blood cell transfusions. He also had splenomegaly, cholelithiasis, and calvarial vault thickening. Pediatricians in Korea must acknowledge thalassemia as a possible diagnosis in children with microcytic hypochromic hemolytic anemia. High level of suspicion will allow timely diagnosis and managements.

[Prevalence of common point mutations of alpha globin gene in Babol, Iran [2005-09]]

Alpha thalassemia is one of the most common hemoglobin disorders. Some combination of alpha globin gene mutations may cause HbH disease with severe anemia or intermediate thalassemia. genotype common deletions are routinely tested for suspicious alpha thalassemia couples but because of lack of information about the nature and frequency of point mutations and higher expenosor of sequencing, less attention was paid to them. This study was done to determine the prevalence of common point mutations of alpha globin gene in Babol, Iran. This descriptive study was carried out on DNA of 153 adult suspected to alpha-thalasemia with deleted alpha-golobolin gene referred to genetic laboratory in Babol, Iran during 2005-09. alpha 1 and alpha 2 genes were amplified by using specific biotinilated primers by PCR method. PCR products were assayed using 11 specific probs corresponding to common point mutations in alpha gene [C19, IVSI [-5nt], C59, Hb constant spring, Hb Icaria, Hb seal Rock, IVSI [148], C14, poly A [-2bp], poly A2, Poly A1] and fixed on byodine C membrabe. Hybridization between the probes and PCR products was visualized after a colorimetric reaction using of conjugated streptavidin peroxidase and TMB [tetra methyle Benzidine] and H[2]O[2]. The prevalence of point mutations in poly A2, 5nt, Hb constant spring and poly A1 were 28.75%, 14.38%, 7.84% and 2.61%, respectively. Point mutation in alpha globin genes was detected in%53.60 out of 153 adults suspected with alpha thalassemia without common deletion mutations

Characterization of alpha thalassemic genotypes by multiplex ligation-dependent probe amplification in the Brazilian population

Alpha-thalassemia is the most common inherited disorder of hemoglobin synthesis. Genomic deletions involving the alpha-globin gene cluster on chromosome 16p13.3 are the most frequent molecular causes of the disease. Although common deletions can be detected by a single multiplex gap-PCR, the rare and novel deletions depend on more laborious techniques for their identification. The multiplex ligation-dependent probe amplification (MLPA) technique has recently been used for this purpose and was successfully used in the present study to detect the molecular alterations responsible for the alpha-thalassemic phenotypes in 8 unrelated individuals (3 males and 5 females; age, 4 months to 30 years) in whom the molecular basis of the disease could not be determined by conventional methods. A total of 44 probe pairs were used for MLPA, covering approximately 800 kb from the telomere to the MSLN gene in the 16p13.3 region. Eight deletions were detected. Four of these varied in size from 240 to 720 kb and affected a large region including the entire alpha-globin gene cluster and its upstream regulatory element (alpha-MRE), while the other four varied in size from 0.4 to 100 kb and were limited to a region containing this element. This study is the first in Brazil to use the MLPA method to determine the molecular basis of alpha-thalassemia. The variety of rearrangements identified highlights the need to investigate all cases presenting microcytosis and hypochromia, but without iron deficiency or elevated hemoglobin A2 levels and suggests that these rearrangements may be more frequent in our population than previously estimated.

Microcytic hypochromic anemia patients with thalassemia: genotyping approach.

BACKGROUND: Microcytic hypochromic anemia is a common condition in clinical practice, and alpha-thalassemia has to be considered as a differential diagnosis. AIMS: This study was conducted to evaluate the frequency of alpha-gene, beta-gene and hemoglobin variant numbers in subjects with microcytic hypochromic anemia. SETTING AND DESIGNS: Population-based case-control study in the Iranian population. MATERIALS AND METHODS: A total of 340 subjects from southwest part of Iran were studied in the Research Center of Thalassemia and Hemoglobinopathies (RCTH), Iran. Genotyping for known alpha- and beta-gene mutations was done with gap-PCR and ARMS. In cases of some rare mutations, the genotyping was done with the help of other techniques such as RFLP and ARMS-PCR. STATISTICAL ANALYSIS: Statistical analysis was carried out by SPSS 11.5 and an independent-sample t test. RESULTS: Out of the total 340 individuals, 325 individuals were evaluated to have microcytic hypochromic anemia based on initial hematological parameters such as MCV<80 fl; MCH<27 pg; the remaining 15 patients were diagnosed with no definite etiology. The overall frequency of -alpha3.7 deletion in 325 individuals was 20.3%. The most frequent mutations were IVS II-I, CD 36/37 and IVS I-110 with frequencies of 6.31%, 5.27% and 1.64%, respectively. Only, there was a significant difference between beta-thalassemia trait and beta-thalassemia major with regard to MCV (P<0.05) and MCH (P<0.05) indices, and also MCH index between beta-thalassemia trait and Hb variants (P<0.05). CONCLUSION: Molecular genotyping provides a rapid and reliable method for identification of common, rare and unknown alpha- and beta-gene mutations, which help to diagnose unexplained microcytosis and thus prevent unnecessary iron supplementation.