ABSTRACT: The aim of this study was to investigate the spectrum of thalassemia mutations in Yunnan Province, Southwestern China. We detected 450 thalassemia patients and carriers by multiplex gap polymerase chain reaction (gap-PCR), PCR reverse dot-blot hybridization and direct sequencing methods in 535 suspected patients. Four types of α-thalassemia (α-thal) mutations, - -(SEA) (59.2%), -α(3.7) (rightward) (19.0%), Hb Constant Spring [Hb CS, α142, Term→Gln, TAA>CAA (α2), α(CS)α] (15.5%), and -α(4.2) (leftward) (6.34%) were detected. Six types of β-thal mutations, the most prevalent being Hb E [β26(B8)Glu→Lys, GAG>AAG or codon 26 (G>A)] (30.5%), followed by codon 17 (A>T) (20.8%), codons 41/42 (-TCTT) (17.5%), IVS-II-654 (C>T) (17.2%), -28 (A>G) (6.95%), and codons 71/72 (+A) (2.42%) were also detected. Other rare mutations were codons 27/28 (+C), IVS-I-1 (G>T), Hb New York [β113(G15)Val→Glu, GTG>GAG], Hb D-Los Angeles [β121(GH4)Glu→Gln, GAA>CAA], codon 5 (-CT), Hb G-Taipei [β22(B4)Glu→Glu (GAA>GGA)], Hb J-Lome [β59(E3)Lys→Asn (AAG>AAC)], Hb J-Bangkok [β56(D7)Gly→Asp (GGC>GAC)], IVS-I-2 (T>C), and -31 (A>C). In this study, we provide a complete mutation spectrum of α- and β-thal mutations and a valuable strategy for accurate molecular diagnostic testing in Yunnan Province, People's Republic of China (PRC).
Hemoglobin 09/2012; 36(5):464-73. · 1.30 Impact Factor
ABSTRACT: To investigate mutation spectrums of α- and β-haemoglobin genes in thalassemia patients and carriers in Yunnan province, and to establish procedures on prenatal gene diagnosis.
Totally 10 033 counseling couples and pregnant women, and 22 cases of children with moderate or severe thalassemia were recruited from 5 parts of Yunnan Province, middle, western, eastern, southern and northern areas, during July 2009 to July 2011. Medical records, including results of haemoglobin electrophoresis, blood routine examination, and gene diagnosis of subjects were collected and saved in an database in Excel software by the Key Laboratory for Birth Defects and Genetic Diseases. Using multiple gap-PCR and PCR-reversed dot blotting kits, DNA samples collected from 1077 cases of haematological positive thalassemia patients and carriers were tested to determine common mutations of the α- or β-haemoglobin genes. The codon regions of haemoglobin genes were sequenced by the Sanger sequencing in cases that the mutation tests were negative. Mutation spectrums of α- and β-haemoglobin genes were concluded. Prenatal gene diagnosis was offered to fetuses who had risk of thalassemia major.
(1) In 1077 cases of haemological screen positive subjects, deletions and mutations of α-haemoglobin gene were tested in 119 subjects among 347 cases suspected as α-thalassemia patients and carriers. Five kinds of deletions and mutations on α-haemoglobin gene were found. In 104 subjects, four kinds of common deletions and mutations onα-haemoglobin gene were determined: --(SEA), -α(3.7), α(CS)α, -α(4.2). Other 14 subjects were double heterozygotes with haemoglobin H disease and severe α-thalassemia phenotypes. A rare mutation of insertion and deletion in α2 haemoglobin gene intron, α(301-24_301-23 indel), was found in one carrier subject. (2) In 1077 cases of haemological screen positive subjects, deletions and mutations of β-haemoglobin gene were tested in 297 subjects among 730 cases suspected as β-thalassemia patients and carriers. Sixteen kinds of β-haemoglobin gene mutations were found, including 7 cases of rare abnormal haemoglobinopathy patients with β-haemoglobin gene mutations. In one case with β(+) phenotype patient, the Codon 5(-CT) mutation at β-haemoglobin gene was found (firstly reported in China). (3) Three fetuses with high risks of α-thalassemia were accepted for prenatal diagnosis. One case of Hb Bart's hydrops syndrome fetus with the genotype --(SEA)/--(SEA), and one case of mild α-thalassemia fetus with the genotype α(CS)α/αα were found. Another one fetus was found with normal α-haemoglobin. In 6 fetuses accepted for prenatal diagnosis due to high risks of β-thalassemia, one case of β-thalassemia major with the genotype CD(17)(A→T)/-28(A→G) was found, 3 fetuses were heterozygote carriers, and 2 fetuses had normal genotypes without mutations found in their parents. Medical terminations for 2 fetuses with severe thalassemia were made according to the choice of pregnant women. Other 7 pregnancies continued to term. Anemia or growth retardation was not found in the 7 infants when following up after given-birth 6 to 12 months.
The mutation spectrums of α- and β-haemoglobin genes of thalassemia patients and carriers in Yunnan province are special, in which β-haemoglobin gene exits more polymorphism in the mutation spectrum. Carrier screening in pregnant women, and offering prenatal gene diagnosis to the high risk pregnancies should be an efficient strategy to prevent thalassemia major.
Zhonghua fu chan ke za zhi 02/2012; 47(2):85-9.
ABSTRACT: To investigate key techniques and intervention in reducing birth defects.
Down's syndrome (DS), trisomy-18 (Edwards syndrome, ES), neural tube defects (NTD), Duchenne muscular dystrophy (DMD), spinal muscular atrophy (SMA), thalassemia, and glucose-6-phosphate dehydrogenase deficiency (G6PD) were chosen as target disease. From Jan. 2007 to Dec. 2009, the condition of intake folic acid were investigated in 5004 pregnant women in Panlong District and Wuhua District of Kunming City. All of the 27 660 pregnant women undergoing prenatal examination were enrolled into the study from the First People's Hospital of Yunnan Province, the Second People's Hospital of Yunnan Province, the First People's Hospital of Qujing City, the Second People's of Qujing City, Qujing Women and Children's Hospital, People's Hospital of Lincang City, Kunming Maria Women's Hospital, Maternal and Infant's Care Unit of Panlong District of Kunming City, Maternal and Infant's Hospital of Dali City. The screening was performed on serum of those pregnant women at 8 - 20(+6) gestational weeks. Prenatal cytogenetic analysis and fetal ultrasonograpy were performed on the high risk or indicated women after genetic counseling. DNA analysis was administered on those women with family or childbearing history of DMD, SMA, thalassemia, or G6PD. Outcome of pregnancy was followed up to evaluate the effect of intervention.
Approximately 30.10% (1506/5004) of pregnant women were administered by oral folic acid during perinatal period. Two thousand three hundred and thirteen women with high risks of DS, ES, or NTD fetuses were observed among 27 660 undergoing maternal serum screening. Two thousand and ninety-six pregnant women including two twins pregnant women were performed cytogenetic analysis. Other 67 pregnant women at high risk of DMD, SMA, thalassemia, and G6PD accepted genetic counseling and prenatal gene analysis. Two thousand one hundred and sixty-three pregnant women (2165 fetuses) underwent prenatal examination. One hundred and two cases chromosome abnormalities, 17 cases NTD, 4 cases DMD, 1 cases α-thalassemia major were found. All of the 91 fetuses with major birth defects were terminated after genetic counseling. Another affected DS fetus in a twin pregnancy dead intrauterine at 24 gestational weeks. Thirty-two women bearing fetuses with balanced translocations or inversions continued their pregnancies. Totally 2071 normal term fetuses were born in the prenatal diagnosis group. Two fetuses with normal chromosome were lost within 1 week after amniocentesis. Four affected DS fetuses were born from their high risk mothers who refused further prenatal diagnosis service. In a random sampling follow-up cohort of 5000 mothers at low risk, none of affected child suffering target diseases was found. The DS detection rate of maternal serum screening was 84% (27/32), with the false positive rate was 6.153% (1702/27 660).
Folic acid intake before conception and in the first trimester would reduce the risk of birth defects, only 1/3 reproductive women took folic acid actively. Maternal serum screening could effectively detect high risk of DS, ES and NTD. The genetic counseling is critical in women at high risk or who had family history of inherited disorders. The prenatal screening and diagnosis combined with routine obstetric care could reduce the incidence of major birth defects, which should become prenatal care strategy in our country.
Zhonghua fu chan ke za zhi 09/2011; 46(9):658-63.