Mitochondria is the main place of biological oxidation and energy transform. Mitochondrial DNA encodes the complex of respiratory chain in mitochondria and its mutation can cause a series of human disease. Mitochondrial DNA mutation which observed in myelodysplastic syndrome (MDS) patients cause the MDS by the mechanism of iron metabolism disorder, gene instability and hemopoietic progenitor cell apoptosis. In this review the characteristics of mitochondrial DNA structure, the mitochondrial DNA mutation and the possible mechanism of mitochondrial DNA mutation in pathogenesis of MDS were summarized.
Anemia, Sideroblastic ; genetics ; DNA, Mitochondrial ; genetics ; Humans ; Myelodysplastic Syndromes ; complications ; genetics ; Point Mutation

5-Aminolevulinate Synthetase/genetics* ; Anemia, Sideroblastic/genetics* ; Genetic Diseases, X-Linked/genetics* ; Humans ; Mutation

Anemia, Sideroblastic ; diagnosis ; genetics ; Asian Continental Ancestry Group ; Genetic Diseases, X-Linked ; diagnosis ; genetics ; Humans ; Pedigree

It was thought that delta-aminolevulinate synthase (ALAS) is the rate-limiting enzyme in the heme biosynthetic pathway. Actually there are two isozymes of ALAS and ALAS2 (erythroid delta-aminolevulinate synthase), they play the leading role in the hemoglobin biosynthetic pathway. Mutations in ALAS2 gene causes X-linked sideroblastic anemia (XLSA). About 25 different mutations in ALAS2 gene have been identified in XLSA patients and two of them were reported by our laboratory. It is possible to cure the patients with XLSA by gene therapy because it is a single gene disorder.
5-Aminolevulinate Synthetase ; genetics ; Anemia, Sideroblastic ; genetics ; therapy ; Chromosomes, Human, X ; genetics ; Genetic Linkage ; Genetic Therapy ; methods ; Humans ; Mutation

OBJECTIVETo raise awareness of molecular pathogenesis and treatment of congenital sideroblastic anemia (CSA).

METHODSA complete blood count and iron metabolism were detected from the proband and other members of the family. Mutation analysis was performed on the complete coding regions of ALAS2 gene by common polymerase chain reaction (PCR) using genomic DNA as a template from members the family. ALAS2 mutations were detected by direct sequencing and mutation types were confirmed by sequencing followed by plasmid cloning.

RESULTSThe proband male presented with microcytic hypochromic anemia (hemoglobin 84 g/L, mean corpuscular volume 64 fL, mean corpuscular hemoglobin 16.5 pg), and iron overload (serum iron 44.7 μmol/L, serum ferritin 3 123 μg/L and transferrin saturation 0.84). A mutation 466 A>G predicting a Lys156Glu amino acid change was identified in the proband and 3 females from the family. The proband was hemizygous for this mutation and presented with microcytic anemia and iron overload, while all 3 heterozygous females showed marginally increased red cell distribution width without any other symptoms. The proband treated with 300 mg of pyridoxine per day and iron chelation therapy with deferoxamine for one year had durable hematopoietic patients improvements, including increase in hemoglobin to 98 g/L and decrease in serum ferritin to 1 580 μg/L.

CONCLUSIONThis was a novel K156E substitution in ALAS2 gene identified in a 3-generation pedigree in China. Our findings emphasized the importance of gene based diagnosis of CSA, and CSA patient with ALAS2 mutation responded to pyridoxine treatment.

5-Aminolevulinate Synthetase ; genetics ; Adult ; Anemia, Sideroblastic ; genetics ; China ; Female ; Genetic Diseases, X-Linked ; genetics ; Heterozygote ; Humans ; Male ; Mutation ; Pedigree

OBJECTIVE: To study the clinical features and gene mutation spectrum of children with sideroblastic anemia (SA) and the clinical value of targeted next-generation sequencing in the molecular diagnosis of children with SA. METHODS: Clinical data were collected from 36 children with SA. Targeted next-generation sequencing was used to detect mutations in SA-related pathogenic genes and genes associated with heme synthesis and mitochondrial iron metabolism. The association between genotype and clinical phenotype was analyzed. RESULTS: Of the 36 patients, 32 had congenital sideroblastic anemia (CSA) and 4 had myelodysplastic syndrome with ring sideroblasts (MDS-RS). Mutations in CSA-related genes were detected in 19 children (19/36, 53%), among whom 9 (47%) had ALAS2 mutation, 4 (21%) had SLC25A38 mutation, and 6 (32%) had mitochondrial fragment deletion. No pathogenic gene mutation was detected in 4 children with MDS-RS. Among the 19 mutations, 89% (17/19) were known mutations and 11% (2/19) were novel mutations. The novel mutation of the ALAS2 gene c.1153A>T(p.I385F) was rated as "possibly pathogenic" and the novel mutation of the SLC25A38 gene c.175C>T(p.Q59X) was rated as "pathogenic". CONCLUSIONS ALAS2 and SLC25A38 gene mutations are commonly seen in children with CSA, but mitochondrial gene fragment deletion also accounts for a relatively high proportion. For children with hypoplastic anemia occurring in infancy, mitochondrial disease should be considered.
5-Aminolevulinate Synthetase ; Anemia, Sideroblastic ; genetics ; Child ; Genetic Diseases, X-Linked ; Humans ; Mitochondrial Membrane Transport Proteins ; Mutation ; Myelodysplastic Syndromes ; Phenotype

Anemia, Sideroblastic ; genetics ; Calreticulin ; genetics ; Humans ; Mutation ; Myelodysplastic-Myeloproliferative Diseases ; genetics ; Phosphoproteins ; genetics ; RNA Splicing Factors ; Ribonucleoprotein, U2 Small Nuclear ; genetics

Myelodysplastic syndromes (MDS) are heterogeneous clonal hematopoietic stem cell disorders with different mechanisms and diverse prognosis. The excess of ring sideroblasts (RS) is an important presentation MDS, but the mechanisms of RS appearance are obscure and the treatment of MDS-RS is intractable. Splicing factors play a very important role in the maturation process of eucaryon mRNA, recent studies indicate that there is a significant causal relationship between splicing factor 3B subunit 1 (SF3B1) mutation and the presence of ring sideroblasts. Lucubrating the downstream molecular of the mutated SF3B1 can facilitate exploring the mechanisms and new therapeutic strategies of MDS-RS.
Anemia, Sideroblastic ; etiology ; genetics ; Animals ; Humans ; Mutation ; Myelodysplastic Syndromes ; complications ; genetics ; Phosphoproteins ; genetics ; RNA Splicing Factors ; Ribonucleoprotein, U2 Small Nuclear ; genetics

No abstract available.
5-Aminolevulinate Synthetase/chemistry/*genetics ; Adult ; Anemia, Sideroblastic/*genetics/pathology ; Asian Continental Ancestry Group/*genetics ; Base Sequence ; Genetic Diseases, X-Linked/*genetics/pathology ; Hemizygote ; Humans ; Male ; Mutation, Missense ; Polymorphism, Single Nucleotide ; Republic of Korea

X-linked sideroblastic anemia (XLSA) is caused by mutations of erythroid-specific 5-aminolevulinate synthetase (ALAS2) gene. In this study a eukaryotic expression vector of ALAS2 was constructed and transfected into eukaryotic cells to observe the expression of ALAS2 gene. The full length cDNA of ALAS2 gene was inserted into plasmid pDs-red2-N1, named pDs-red2-N1/ALAS2. Then, the vector was transfected into K562 cells via electroporation. At 48 hours after transfection, total RNA from K562 cells was extracted, expressions of ALAS2 gene and protein with red fluorescence in the K562 cells were detected by RT-PCR and flow cytometry, respectively. The vector was also transfected into COS 7 cells via liposome. Both mRNA and protein expression in COS7 cells were detected by RT-PCR and fluorescence microscopy. The result showed that after the pDs-red2-N1/ALAS2 eukaryotic expression vector was digested by KpnI and BamHI, two fragments of 4 700 bp and 1 764 bp were displayed by electrophoresis on agarose gel. Sequence method confirmed that the sequence was correct. RT-PCR amplified the total RNA extracted from the transfected K562 and COS7 cells, and could find mRNA of ALAS2 gene that can't be found in K562 and COS7 cells usually. The expressions of both fluorescein and ALAS2 were significantly increased. The percentage of positive cells reached about 19.2% and 10.7%, respectively. ALAS2 expression lasted for 10 days in COS7 cells and the peak was at the third day. It is concluded that the eukaryotic expression vector of ALAS2 gene is successfully constructed; K562 and COS7 cells transfected with the vector via electroporation and liposome can express ALAS2 protein. So, the vector has the potential in gene replacement and can be used for patients with XLSA in future.
5-Aminolevulinate Synthetase ; genetics ; Anemia, Sideroblastic ; genetics ; therapy ; Animals ; COS Cells ; Chromosomes, Human, X ; Genetic Linkage ; Genetic Therapy ; Genetic Vectors ; Humans ; K562 Cells ; Microscopy, Fluorescence ; Reverse Transcriptase Polymerase Chain Reaction