Application of real-time PCR-based multicolor melting curve with automatic analysis system in pregestational and prenatal thalassemia diagnoses.

BACKGROUND: To evaluate the value of the real-time PCR-based multicolor melting curve analysis (MMCA) with an automatic analysis system used in a mass thalassemia screening and prenatal diagnosis program. METHODS: A total of 18,912 peripheral blood samples from 9456 couples and 1150 prenatal samples were detected by MMCA assay. All prenatal samples were also tested by a conventional method. Samples with unknown melting peaks, unusual peak height ratios between a wild allele and a mutant allele, or a discordant phenotype-genotype match were further studied by using multiplex ligation-dependent probe amplification (MLPA) or Sanger sequencing. All MMCA results were automatically analyzed and manually checked. The consistency between MMCA assay and conventional methods among prenatal samples was investigated. RESULTS: Except for initiation codon (T > G) (HBB:c.2T > G), all genotypes of thalassemia inside the scope of conventional methods were detected by MMCA assay. Additionally, 27 carriers with 10 rare HBB variants, 13 with α fusion gene, 1 with a rare deletion in α globin gene, and 1 with rare HBA variant were detected by using MMCA assay. CONCLUSION: MMCA can be an alternative approach used in routine thalassemia carrier screening and prenatal diagnosis for its high throughput, sufficient stability, low cost, and easy operation.

Prenatal Silver-Russell Syndrome in a Chinese Family Identified by Non-Invasive Prenatal Testing.

Russell-Silver syndrome (SRS) is a rare condition characterized by poor growth before and after birth along with multiple physical and psychosocial characteristics such as short stature, characteristic facial features, body asymmetry, feeding difficulties, and learning disabilities. In this study, we report a family with 2 recurrent SRS pregnancies due to a derivative chromosome 15 that is the result of a maternally derived t(11;15) translocation, detected by non-invasive prenatal testing (NIPT). The 2 SRS fetuses were diagnosed by chromosomal microarray analysis, but a balanced, reciprocal translocation of the mother was disclosed by the combination of routine karyotyping and FISH. This study demonstrates that NIPT has the ability to identify submicroscopic copy number variations (CNVs) in fetuses, which in some cases may result from a parent being a balanced rearrangement carrier. Because of the differences in resolution and the various benefits and limitations of each genetic technique, great care must be taken when deciding on which test(s) to employ in family studies.

Detection of rare thalassemia mutations using long-read single-molecule real-time sequencing.

Gap- polymerase chain reaction (PCR), reverse dot-blot assay (RDB), real-time PCR based multicolor melting curve analysis (MMCA assay), multiplex ligation-dependent probe amplification (MLPA) and Sanger sequencing are conventional methods to diagnose thalassemia but all of them have limitations. In this study, we applied single-molecule real-time (SMRT) sequencing following multiplex long-range PCR to uncover rare mutations in nine patients and their family members. The patients with different results between Gap-PCR and MMCA assay or with phenotype not matching genotype were included. Using SMRT sequencing, we first identified the carriers with αααanti3.7/HKαα, -α762bpα/αα (chr16:172,648-173,409), ααfusion/αQSα (in a trans configuration), two cases with novel gene rearrangements and another case with a novel 341 bp insertion in α-globin gene cluster, respectively. One carrier with --SEA/αααanti4.2, and two carriers with the coexistence of globin variant and an α-globin gene duplication were also found. Most importantly, we could determine two defects in α-globin gene cluster being a cis or trans configuration in a single test. Our results showed that SMRT has great advantages in detection of α-globin gene triplications, rare deletions and determination of a cis or trans configuration. SMRT is a comprehensive and one-step method for thalassemia screening and diagnosis, especially for detection of rare thalassemia mutations.

Use of noninvasive prenatal screening with cell-free DNA in late pregnancy with sonographic soft markers.

OBJECTIVE: To report the experience on the clinical use of noninvasive cell-free (cf) DNA testing at late pregnancy. STUDY DESIGN: A cohort of 1539 women with singleton gestations of ≥23 weeks receiving cfDNA testing in a 3-year period were included for this study. Maternal characteristics and data on cfDNA testing, confirming diagnostic testing and pregnancy outcome were reviewed. RESULTS: During the study period, 1539 patients had cfDNA testing although they had a normal first-trimester screening. Of these, 7 cases had a positive result, including 5 for chromosome 21, one for chromosome 18, and one for chromosome 13. The most common indication was soft markers on ultrasound, followed by polyhydramnios. Cytogenetic testing was done for the 5 trisomy 21 positive cases, and confirmed the cfDNA results. Confirmative testing was declined in the two cases with positive cfDNA for trisomy 18/13, and postnatal placental investigation showed confined placental mosaicism with normal karyotype in the cord blood of newborns. There were no confirmed false negatives reported. The cfDNA screening achieved a positive predictive value of 71.4 % and a negative predictive value of 100 % in late pregnancy for common trisomies. CONCLUSIONS: There is no gestational age upper limit for cfDNA use in the clinical practice. Most of the time, cfDNA was used in late gestation for reassurance in patients who is at low risk for aneuploidies but had second-trimester soft markers on ultrasound.

MiR-29a inhibits invasion and metastasis of cervical cancer via modulating methylation of tumor suppressor SOCS1.

Aims: To investigate roles of miR-29a-DNMT1-SOCS1 axis in cervical cancer invasion and migration. Materials & methods: The methylation level of SOCS1 was determined by methylation specific PCR. The cell apoptosis, proliferation, migration and invasion were examined by Annexin-V/PI staining, MTT and colony formation assays, plus scratch and transwell assays respectively. The expressions of epithelial-mesenchymal transition and NF-κB related proteins were determined by western blotting. Results: MiR-29a was downregulated, accompanied with DNMT1 upregulation and SOCS1 downregulation in cervical cancer tissues. MiR-29a suppressed DNMT1, inhibited SOCS1 promoter methylation and upregulated its expression. Moreover, miR-29a promoted cell apoptosis, suppressed proliferation, inhibited migration and invasion via inactivation of NF-κB signaling pathway in cervical cancer cells. Conclusion: MiR-29a-DNMT1-SOCS1 axis plays an important role on invasion and metastasis in cervical cancer via NF-κB signaling pathway.

Prenatal diagnosis of Smith-Magenis syndrome in two fetuses with increased nuchal translucency, mild lateral ventriculomegaly, and congenital heart defects.

OBJECTIVE: Smith-Magenis syndrome (SMS) is a multiple congenital anomalies/mental retardation disorder characterized by an interstitial deletion involving chromosome 17p11.2 containing the retinoic acid-induced 1 (RAI1) gene or due to mutation of RAI1. Few cases have been reported in the medical literature regarding prenatal diagnosis of SMS. We report on the prenatal diagnosis of SMS in two fetuses with increased nuchal translucency (NT), mild lateral ventriculomegaly, and congenital heart defects by whole-genome and high-resolution chromosome microarray analysis (CMA). CASE REPORT: The CMA result of Fetus 1, which had increased NT, mild lateral ventriculomegaly, tricuspid regurgitation, and right aortic arch with left ductus arteriosus, revealed a de novo 4.79-Mb deletion at 17p12p11.2. Fetus 2 had increased NT, pulmonary stenosis, and a ventricular septal defect, and showed a de novo 3.68-Mb deletion at 17p11.2. CONCLUSION: The findings further confirm that increased NT is associated with genetic syndromes, and brain imaging is necessary for SMS fetuses. Both deletions encompass the SMS "critical region", which includes many genes including RAI1. However, the precise gene(s) responsible for the heart defects in SMS remain unclear; further efforts should be undertaken to understand the molecular basis of this syndrome.

Association of an α-globin gene cluster duplication and heterozygous ß-thalassemia in a patient with a severe thalassemia syndrome.

We describe a new case of a ß-thalassemia (ß-thal) heterozygote with the mutation IVS-II-654 (C>T) presenting with a transfusion-dependent phenotype. Multiplex ligation-dependent probe amplification (MLPA) and array comparative genomic hybridization (CGH) analyses of the α-globin gene cluster revealed a full duplication of the α-globin genes including the upstream regulatory element. The duplicated allele and the normal allele in trans resulted in a total of six active α-globin genes. The severe clinical phenotype seemed to be related to the considerable excess of the α- and ß-globin deficit caused by the presence of the ß-thal. α-Globin cluster duplication should be considered in patients heterozygous for ß-thal who show a more severe phenotype than ß-thal trait.

A preliminary evaluation of attenuated total reflection Fourier transform infrared spectroscopy for the hematological analysis of thalassemias.

OBJECTIVES: The effectiveness of attenuated total reflection Fourier transform infrared spectroscopy for the hematological analysis of thalassemias was evaluated. DESIGN AND METHODS: The correlations of hemoglobin, mean corpuscular volume and mean corpuscular hemoglobin between routine method and attenuated total reflection Fourier transform infrared spectroscopy were analyzed using linear regression analysis. Appropriate cut-off values of predicted mean corpuscular volume and predicted mean corpuscular hemoglobin in screening of thalassemias were derived from the receiver operator characteristic curve conducted on 103 subjects. RESULTS: Obvious positive correlations of hemoglobin (beta=0.876, R(2)=0.791, P<0.001), mean corpuscular volume (beta=0.656, R(2)=0.516, P<0.001) and mean corpuscular hemoglobin (beta=0.674, R(2)=0.583, P<0.001) were observed between routine method and attenuated total reflection Fourier transform infrared spectroscopy. Based on the receiver operator characteristic curve analysis, the best cut off value of predicted mean corpuscular volume for the phenotype-positive subjects was found to be 79.9 fl with a sensitivity of 100.0% and a specificity of 97.8%, and the proposed cut off value of predicted mean corpuscular hemoglobin was 27.3 pg with a sensitivity of 100.0% and a specificity of 96.8%. The area under curve was 0.996 for predicted mean corpuscular volume and 0.992 for predicted mean corpuscular hemoglobin, respectively. CONCLUSIONS: The established method could be an additional potentially promising tool for the preliminary screening of thalassemias in population prevention and control program. The main advantage of this method is no unwanted chemical regents compared with conventional method. Strategy for the development of this method could be of use for the other important parameters of thalassemias.

Rapid determination of human globin chains using reversed-phase high-performance liquid chromatography.

Reversed-phase high-performance liquid chromatography (RP-HPLC) of human globin chains is an important tool for detecting thalassemias and hemoglobin variants. The challenges of this method that limit its clinical application are a long analytical time and complex sample preparation. The aim of this study was to establish a simple, rapid and high-resolution RP-HPLC method for the separation of globin chains in human blood. Red blood cells from newborns and adults were diluted in deionized water and injected directly onto a micro-jupiter C18 reversed-phase column (250 mm × 4.6 mm) with UV detection at 280 nm. Under the conditions of varying pH or the HPLC gradient, the globin chains (pre-ß, ß, δ, α, (G)γ and (A)γ) were denatured and separated from the heme groups in 12 min with a retention time coefficient of variation (CV) ranging from 0.11 to 1.29% and a peak area CV between 0.32% and 4.86%. Significant differences (P<0.05) among three groups (normal, Hb H and ß thalassemia) were found in the area ratio of α/pre-ß+ß applying the rapid elution procedure, while P≥0.05 was obtained between the normal and α thalassemia silent/trait group. Based on the ANOVA results, receiver operating characteristic (ROC) curve analysis of the δ/ß and α/pre-ß+ß area ratios showed a sensitivity of 100.0%, and a specificity of 100.0% for indicating ß thalassemia carriers, and a sensitivity of 96.6% and a specificity of 89.6% for the prediction of hemoglobin H (Hb H) disease. The proposed cut-off was 0.026 of δ/ß for ß thalassemia carriers and 0.626 of α/pre-ß+ß for Hb H disease. In addition, abnormal hemoglobin hemoglobin E (Hb E) and Hb Westmead (Hb WS) were successfully identified using this RP-HPLC method. Our experience in developing this RP-HPLC method for the rapid separation of human globin chains could be of use for similar work.