[Study on the dynamic changes of D-dimer during pregnancy and early puerperium]

Objective: To explore the dynamic changes of D-dimers during pregnancy and early puerperium(within 3 days postpartum). Methods: A retrospective study was performed among 8 367 healthy women who had term singleton delivery in Women's Hospital, School of Medicine, Zhejiang University from January 2007 to December 2014. D-dimers concentrations during pregnancy and early puerprium of all the cases were collected. Data of 21 065 D-dimers tests were assigned to 5 groups according to the time of sampling, including early pregnancy(≤12 gestation weeks), middle pregnancy(12-28 gestation weeks), late pregnancy(>28 gestation weeks), 1 postpartum(within 48 hours postpartum)and 2 postpartum(48- 72 hours postpartum). The D-dimers concentrations in different groups were compared. The effect of delivery mode on D-dimers of early pureperium was analyzed. The correlation between D-dimers and the thromboembolic disease was also explored. In this study, Student's t-test and Wilcoxon rank sum test were used for statistical analysis. D-dimers concentration ≤0.5 mg/L was used as the normal range. Results: (1)D-dimers concentrations during pregnancy were higher than the non-pregnant women(P<0.01), but there was no statistical difference between early pregnancy and late pregnancy(P=0.820). D-dimers concentration in the 1 postpartum group was higher than that of early pregnancy group or late pregnancy group(P<0.01). But in the 2 postpartum group, it was lower than early pregnancy, late pregnancy and 1 postpartum groups.(2)D-dimers in cesarean section cases was significantly higher than in vaginal delivery cases in each period of pregnancy and early pueprium.(3)The 95%CI of D-dimers in early pregnancy, late pregnancy, 48 hours after vaginal delivery, 48- 72 hours after vaginal delivery, ≤48 hours after cesarean section, 48- 72 hours after cesarean section were 0.58-8.28, 0.47-11.52, 1.04-9.59, 0.87-5.22, 1.07-11.58 and 1.00-6.23 mg/L, respectively.(4)In 6 cases with thromboembolic disease, D-dimers was 6.89- 19.89 mg/L, with the mean value of 13.66 mg/L. It was significantly higher than normal range. In 3 cases, all after cesarean section, with lower extremity vein thrombosis within 48 hours postpartum, the D-dimers concentrations, 9.77, 8.65 and 6.89 mg/L respectively, were in the 95% CI of the study population after cesarean section. Conclusions: D-dimers concentration of 0.5 mg/L is not suitable for venous thromboembolism screening during pregnancy. D-dimers concentration in pregnancy and early puerprium is higher than non-pregnancy. It increases in the very early period postpartum and decreases with time. D-dimers should not be a routine screening test to exclude thromboembolic disease in pregnant women without high risk factors and clinical manifestation of thromboembolic disease.

A novel NF1 frame-shift mutation (c.702_703delGT) in a Chinese family with neurofibromatosis type 1

This study aimed to characterize the clinical features of a Chinese pedigree with neurofibromatosis type 1 (NF1) and to identify mutations in the NF1 gene. In this three-generation family containing 8 members, 5 had been diagnosed with NF1 and the others were asymptomatic. All members of the family underwent complete medical examinations. Molecular genetic analyses were performed on all subjects included in the study. All exons of NF1 were amplified by polymerase chain reaction, sequenced, and compared with a reference database. Possible changes in function of the protein induced by amino acid variants were predicted by bioinformatic analysis. In this family, the 5 patients presented different clinical phenotypes, but all manifested typical café-au-lait macules. One novel frame-shift mutation, c.702_703delGT, in exon 7 of NF1 was identified in all affected family members, but not in the unaffected family members or in 102 normal controls. This mutation generates a premature stop codon at amino acid position 720. Additionally, a synonymous mutation c.702 G>A was found in 3 family members, including 2 affected and 1 normal individuals. In conclusion, our study suggests that a novel c.702_703delGT frame-shift mutation in NF1 is likely to be responsible for the pathogenesis of NF1 in this family. To the best of our knowledge, it is the first time that a c.702_703delGT mutation has been identified in a family with neurofibromatosis type 1.

[Study on expression of ELAM-1 and ICAM-1 mRNA on microvascular endothelial cells during focal cerebral ischemia/reperfusion]

AIM

To evaluate the role of ELAM-1 and ICAM-1 in the course of inflammatory reactions during focal brain ischemia/reperfusion.

METHODS

The focal brain ischemia/reperfusion model is carried by occluding middle cerebral artery. The expression of ELAM-1 and ICAM-1 mRNA after ischemia/reperfusion was evaluated with RT-PCR.

RESULTS

No ELAM-1 and ICAM-1 mRNA were detected in the sham-operated cortex and only little in the nonischemic cortex. The expression of ELAM-1 and ICAM-1 mRNA were upregulated at 1 hour, peaked at 6 hour and 3 hour respectively and remained elevated for up to 48 hours after ischemia/reperfusion.

CONCLUSION

ELAM-1 and ICAM-1 participate in brain injury during focal ischemia/reperfusion and both of them play an important role in leukocyte infiltration into the ischemic tissues.

Molecular basis of asymptomatic beta-thalassemia major in an African American individual

The beta-thalassemia syndromes are a heterogeneous group of genetic disorders characterized by reduced or absent expression of the beta-globin gene. To date, over 300 beta-thalassemia alleles have been characterized in or around the beta-globin region. Thalassemia major is severe anemia necessitating chronic blood transfusions, splenectomy, iron chelation therapy, and bone marrow transplantation. Usually thalassemia major results from homozygosity or compound heterozygosity for severe betaO- and/or beta+-thalassemia mutations. Thalassemia intermedia is a clinical diagnosis that describes a symptomatic but less severe condition than beta-thalassemia major. beta-thalassemia intermedia may arise from several different combinations of alpha- and/or beta-thalassemia mutations. Heterozygous beta-thalassemia is typically characterized by a mild microcytic hypochromic anemia without any significant clinical implications. In this report, we describe a 63-year-old Africian American woman with asymptomatic homozygous beta-thalassemia, who seems to carry 2 copies of the -29 mutation in the promoter region of the beta-globin gene. Her elevated hemoglobin F level of 83% was associated with heterozygosity for the Xmn I polymorphism upstream of the Ggamma-globin gene. Southern blot analysis at the alpha-globin locus did not show any deletion that would account for the mildness of her phenotype. Therefore, homozygosity for the -29 mutation along with the Xmn I polymorphism appears to confer an extremely mild beta-thalassemia phenotype. This observation has important implications in the prenatal diagnosis and genetic counseling of families segregating this type of genetic defect.

Prenatal diagnosis of unusual hemoglobinopathies

While analyzing 280 hemoglobinopathy kindreds with prescribed molecular tests, 3 unusual mutations were observed that required additional characterization. In the first case, the hypervariable region flanking the alpha-globin genes generated an intermediate length 8.2 kb psi zeta-globin gene fragment on a Southeast Asian chromosome with two deleted alpha-globin genes. Rehybridization of the Southern blot with alpha-globin probe distinguished the mutation unambiguously. In the second case, restriction enzyme analysis of a PCR amplified black beta-globin gene detected a novel beta-83 point mutation adjacent to a promoter element. In the third case, which was uninformative with available allele specific oligonucleotides (ASOs), total genomic PCR amplification and sequencing identified a single basepair insertion in codon 36/37 of an Iranian beta-globin gene that shifted the reading frame and obliterated gene activity. Developing additional region-specific ASOs will further diminish the number of cases that must be characterized by genomic PCR sequencing.

Reverse dot blot probes for the screening of beta-thalassemia mutations in Asians and American blacks

We have optimized a battery of reverse dot blot oligonucleotide probes for detecting the most common beta-globin gene mutations in Asians and American Blacks. These probes allow a high degree of coverage of mutant chromosomes in these two populations and are useful in mutation screening and prenatal diagnosis. When coupled with the Mediterranean subset of probes, a 95% worldwide coverage of beta-thalassemia mutations should be possible. The use of these probes in the reverse dot blot system should allow the distribution of premade strips and application to automated screening.

Carrier detection and prenatal diagnosis of hemoglobinopathies in Ontario

The province of Ontario has a total population of approximately 10 million people, with approximately 20% being of African, Southeast Asian, East Indian, Mediterranean, or Middle Eastern ancestry in whom the gene frequency for hemoglobinopathies is relatively high. In 1989, the Ontario Ministry of Health funded the establishment of the Provincial Hemoglobinopathy DNA Diagnostic Laboratory located at the McMaster University Medical Centre in Hamilton, Ontario. The Laboratory provides DNA analysis to identify the globin gene mutations in carriers and affected individuals, and performs prenatal diagnosis for severe hemoglobinopathies. Annually, more than 400 patient samples are referred to the Laboratory for investigation, of which 25-35 are fetal samples from pregnancies at risk for either homozygous alpha-thalassemia, beta-thalassemia major, or sickling disorders. We have detected more than 70 different globin gene mutations, including several mutations not previously reported in the literature. Here we present examples of the approaches used to detect globin gene mutations in a heterogeneous "at risk" population such as in Ontario, and discuss the impact of this service on patient care, genetic counselling, and the incidence of severe hemoglobinopathies in Ontario.

Expression of embryonic zeta-globin and epsilon-globin chains in a 10-year-old girl with congenital anemia

A 10-year-old Danish girl with congenital anemia is described. At birth, she had severe anemia and erythroblastosis and was transfused a number of times during the first year. The need for transfusions has since declined steadily. Her reticulocyte counts varied between 2% and 15%, and her bone marrow aspirate showed some dyserythropoietic features. Her hemoglobin F level was consistently elevated, up to as much as 41%. Her erythrocytes had a normal level of I antigen but an undetectable level of i antigen. Moreover, embryonic zeta-globin and epsilon-globin chains were present in some of her circulating erythrocytes. These findings may represent the manifestations of a new variant of congenital anemia.

A short-term trial of butyrate to stimulate fetal-globin-gene expression in the beta-globin disorders

BACKGROUND

Fetal-globin (gamma-globin) chains inhibit the polymerization of hemoglobin S (sickle hemoglobin) and can functionally substitute for the beta-globin chains that are defective or absent in patients with the beta-thalassemias. Identifying safe mechanisms to stimulate fetal-hemoglobin production is therefore of great interest. Previous studies have shown that administering butyrate selectively stimulates the promoter of the human fetal-globin gene and leads to increases in gamma-globin--gene expression in the developing fetus, cultured cells, and animal models.

METHODS

To determine whether butyrate can stimulate fetal-globin production in humans, we treated three patients (3 to 13 years old) with sickle cell anemia and three patients (7 to 27 years old) with beta-thalassemia syndromes with a short course of intravenous infusions of arginine butyrate. The drug was infused continuously for either two or three weeks; the initial dose was 500 mg per kilogram of body weight per day. Globin-chain ratios, proportions of reticulocytes producing hemoglobin F (F reticulocytes), and levels of gamma-globin messenger RNA (mRNA) were determined before and during treatment.

RESULTS

In all six patients, fetal-globin synthesis increased by 6 to 45 percent above pretreatment levels (P < 0.01). The proportion of F reticulocytes increased about twofold, and the level of gamma-globin mRNA increased twofold to sixfold. The increase in gamma-globin synthesis led to improvement in the globin-chain ratios in the patients with thalassemia. The treatment of one patient was extended for seven weeks, and her hemoglobin level increased from 4.7 to 10.2 g per deciliter (2.9 to 6.3 mmol per liter). Side effects were minimal; one patient had a transient increase in serum aminotransferase concentrations.

CONCLUSIONS

In patients with beta-hemoglobinopathies butyrate, a natural fatty acid, can significantly and rapidly increase fetal-globin production to levels that can ameliorate beta-globin disorders. Further trials of this class of compounds are warranted to determine long-term tolerance and efficacy in patients with sickle cell anemia or beta-thalassemia.

Rapid and simultaneous typing of hemoglobin S, hemoglobin C, and seven Mediterranean beta-thalassemia mutations by covalent reverse dot-blot analysis: application to prenatal diagnosis in Sicily

The molecular lesions causing beta-thalassemia in Sicily can be subdivided into two groups. One that occurs at a 71% frequency and consists of the beta 39, IVS 1,110 and IVS 1,6 mutations and the other group at a 20% frequency comprising the -87, beta s, IVS 1,1 and IVS 2,745 mutations. The identification of all these mutations by polymerase chain reaction (PCR) and conventional dot-blot hybridization has been time consuming and expensive. In this article, we describe the implementation of the reverse dot-blot (RDB) hybridization as a rapid nonradioactive method for the identification of the nine most frequent molecular lesions in the beta-globin gene (-87, beta s, beta c, IVS 1,1, IVS 1,6, IVS 1,110, beta 39, IVS 2,1, IVS 2,745) in Sicily. Sixty prenatal diagnoses were performed by this RDB assay, each of which was confirmed by dot-blot/ASO hybridization; thus demonstrating the accuracy of the RDB. The main advantage of this assay is the rapid typing of an individual's DNA for many mutations in a single working day. Because the mutations in this assay are representative for the Mediterranean region, this mutational panel can also be extended to the screening of beta-thalassemia from other Mediterranean regions.

Clinical course and molecular characterization of a compound heterozygote for sickle hemoglobin and hemoglobin Kenya

We describe a 25-year-old black woman who presented with a long history of anemia requiring transfusions during childhood and adolescence. Molecular analysis revealed her to be a compound heterozygote for the sickle mutation and the approximately 22.7 kb deletion associated with hemoglobin Kenya. This patient's clinical course was more severe than previously reported for the Hb S/Hb Kenya genotype, a probable consequence of concomitant iron deficiency.

Two novel beta-thalassemia mutations in the 5' and 3' noncoding regions of the beta-globin gene

Two novel beta-thalassemia mutations are described. The first mutation, found in an Italian family, is a G----A substitution in nucleotide (nt) +22 relative to the beta-globin gene Cap site. This mutation creates a cryptic ATG initiation codon, the utilization of which for translation would result in premature termination 36 bp 3' downstream. The second mutation, found in an Irish family, is a T----C substitution in nt +1570, or 12 bp 5' upstream of the AATAAA polyadenylation signal in the 3' noncoding region. It is postulated that this mutation leads to destabilization of the encoded beta-globin mRNA.

A rapid and simple electrophoretic method for the detection of mutations involving small insertion or deletion: application to beta-thalassemia

The 1.8-kb beta-globin gene fragments of DNAs from individuals heterozygous for nine different beta-thalassemia mutations involving 1, 2, 3, 4, or 25 basepair (bp) insertions or deletions were amplified by the polymerase chain reaction (PCR). The PCR products were subjected to electrophoresis on aqueous 8% polyacrylamide gel. In each heterozygote with either a 2 to 25 bp deletion, but not with a 1 bp insertion, two slower migrating bands representing heteroduplexes in addition to the 1.8-kb homoduplex band were seen. The electrophoretic positions of these slower migrating bands were characteristic of each mutation studied. By co-amplification with known normal DNA, it was also possible to distinguish DNAs from normal individuals and from individuals who are homozygous for the small insertion/deletion mutations. These studies demonstrate that the heteroduplex formation generated in PCR can be applied as a simple method in the diagnosis of insertion/deletion mutations involving 2 to 25 bp in beta-thalassemias as well as in other genetic disorders.

Hb S/beta zero-thalassemia due to the approximately 1.4-kb deletion is associated with a relatively mild phenotype

We report a relatively mild phenotype associated with two siblings who are compound heterozygotes for Hb S and a beta zero-thalassemia mutation due to a approximately 1.4-kb deletion of the 5' region of the beta-globin gene. Each is found to have unusually high levels of Hb A2 and Hb F, accounting for more than 20% of the total hemoglobin. These may interfere with intracellular Hb S polymerization, thus leading to a mild clinical course.

A new frameshift beta zero-thalassemia mutation (codons 27-28 +C) found in a Chinese family

A new beta zero-thalassemia mutation, a frameshift mutation with an insertion of a single cytosine nucleotide in codon 27-28, is described. The propositus, who is compound heterozygous for this mutation and the IVSII-654 C----T beta zero-thalassemia mutation, has the phenotype of severe beta-thalassemia major.

High hemoglobin A2 beta 0-thalassemia due to a 532-basepair deletion of the 5' beta-globin gene region

We identify and characterize a novel beta 0-thalassemia mutation that is associated with an unusually high level of hemoglobin (Hb) A2 in the heterozygote. This newly discovered mutation is caused by a 532-basepair deletion that extends from positions -454 to + 78 relative to the mRNA cap site of the beta-globin gene. The propositi are 9-month-old fraternal twins. One of the twins is a compound heterozygote for the deletion and Hb S, the other is a compound heterozygote for the deletion and Hb C.

Identification of the multiple beta-thalassemia mutations by denaturing gradient gel electrophoresis

We used denaturing gradient gel electrophoresis to detect the beta-thalassemia mutations in the Chinese population. By amplifying the beta-globin gene in four separate fragments and electrophoresing the amplified DNA in two gels, we were able to distinguish all the 12 known mutations on the basis of the mobility of the homoduplexes and heteroduplexes. We conclude that denaturing gradient gel electrophoresis offers a nonradioactive means of detecting multiple mutations in genetic disorders.

Beta-thalassemia mutations in Indonesia and their linkage to beta haplotypes

A total of 72 chromosomes from 36 Indonesian patients, 23 with beta-thalassemia major and 13 with Hb E-beta-thalassemia, were analyzed by specific oligonucleotide hybridization after DNA amplification. Thirteen had the beta E mutation (codon 26 GAG----AAG). Of the 59-beta-thalassemic chromosomes, 32 were of the variant IVS-1 nt5 (G----C). Seven had the mutation IVS-2 nt654 (C----T), one had the mutation codon 41/42 (deletion CTTT), and one had the mutation codon 17 (AAG----TAG). Another six with the mutation IVS-1 nt1 (G----T), one with the mutation IVS-1 nt1 (G----A), four with the mutation codon 15 (TGG----TAG), one with a mutation codon 30 (AGG----ACG), and one with a mutation codon 35 (deletion C) were first identified by direct sequencing of a patient's genomic DNA followed by further hybridizing other patients' DNA with the appropriate oligonucleotide probes. Five did not carry the common mutations previously described in Asian populations. The four most prevalent mutations encountered made up 83% of the total number of beta-thalassemic chromosomes studied. The most common mutation, IVS-1 nt5 (G----C), was mostly associated with two different haplotypes.

A new TATA box mutation detected at prenatal diagnosis for beta-thalassemia

During the course of prenatal diagnosis for beta-thalassemia in Chinese patients, we encountered a mutation that was not detectable by oligonucleotides for the known Chinese mutations. Amplification of the beta-globin gene by the polymerase chain reaction and direct DNA sequencing revealed a previously undescribed -30 TATA box mutation which was carried by the father. Prenatal diagnosis was achieved, and the fetus did not inherit this beta-thalassemia allele.

Rapid prenatal diagnosis of beta thalassemia using DNA amplification and nonradioactive probes

We used in vitro DNA amplification by the polymerase chain reaction and nonradioactive probes for prenatal diagnosis of beta thalassemia in Chinese from the Guangdong province. Exact molecular diagnoses were made in all 20 fetuses studied over a 6-month period. We conclude that this method of prenatal diagnosis for beta thalassemia is a viable approach in many parts of the world where this disease is common.

Hemoglobin constant spring defined by specific oligonucleotide hybridization and hemoglobin D Punjab (beta 121----Gln) in a Batak Indonesian family

A Batak Indonesian from North Sumatra with hemoglobin (Hb) D Punjab (alpha 2 beta 2 121----Gln) and hemoglobin Constant Spring (Hb CoSp) is described. The 24-year-old man did not have clinical symptoms, and his hematological indices were normal. However, he had a persistent slight elevation of fetal hemoglobin level. His mother and his brother were heterozygous for Hb D Punjab; his father had Hb CoSp trait. A sister did not have any abnormal hemoglobin. To show the exact molecular defect leading to the synthesis of Hb CoSp in this family, genomic DNA from the father was analyzed by hybridization with synthetic oligonucleotides. Genomic DNA was digested with Sst I and Hind III producing a 1.05-kb fragment from the 3' end segment of the alpha 2-globin gene, including the termination codon. Two nonadecamers were synthesized to serve as probes: one, entirely homologous to the normal 3' end of alpha 2A-globin gene sequence, including the termination codon TAA, the other different from it by a replacement of the T in the termination codon TAA with C, changing it to CAA, the codon for the amino acid glutamine. DNA from normal controls gave a positive signal with the normal alpha 2TAA oligonucleotide probe but negative with the alpha 2 CAA probe. The father of propositus who had Hb CoSp trait gave a positive signal with the normal alpha 2TAA oligonucleotide probe as well as with the alpha 2CAA oligonucleotide probe, showing him to be heterozygous for the alpha 2CAA-globin gene. This result shows that the Hb CoSp in the Batak family is indeed due to a replacement of T by C in the TAA termination codon of the alpha 2-globin gene changing it to CAA the condon for glutamine. This explains the resulting readthrough of the untranslated sequence of the mRNA.

A simple approach to prenatal diagnosis of beta-thalassemia in a geographic area where multiple mutations occur

We describe a simple approach for detecting beta-thalassemia mutations in geographic areas such as southern China where multiple mutations are known to occur. Segments of the beta-globin gene were amplified in vitro by using the polymerase chain reaction. Dot blot hybridization of the amplified DNA with oligonucleotide probes corresponding to the six mutations found in southern China could directly identify the mutations causing beta-thalassemia in the affected families. The increased number of target sequences after amplification allows the use of 35S-labeled probes, which are reusable for up to 3 months. The mutations can be determined in two days.

Molecular basis of beta thalassemia in south China. Strategy for DNA analysis

The phenotype of beta thalassemia can be caused by over 40 different mutations. To set up a prenatal diagnosis program using DNA analysis, it is important to determine the type and frequency of mutation in a particular geographic area. We have delineated the molecular lesions that cause beta thalassemia in the Guangdong province of China, and found six mutations in four different haplotypes. The surprising finding that five of these mutations each occur in two different haplotypes suggests the occurrence of crossing over or gene conversion events at the beta-globin locus. The delineation of the haplotypes and mutations will permit the choice of the appropriate probes for prenatal detection of beta thalassemia in this part of China.