APA scoring system: a novel predictive model based on risk factors of pregnancy loss for recurrent spontaneous abortion patients.

The aim of this study was to analyse the risk factors of pregnancy loss of patients with recurrent spontaneous abortion (RSA) and develop a scoring system to predict RSA. Clinical data of 242 cases, with RSA who were treated at Fujian Provincial Maternity and Children's Hospital, were selected. The factors of pregnancy loss for RSA patients were evaluated by univariate and multivariate analyses. There were 242 RSA patients, of whom 34 (14.0%) developed pregnancy loss. A multivariate analysis showed the following adverse risk factors for RSA: antinuclear antibody spectrum, protein s deficiency and antiphospholipid antibodies. The pregnancy loss rates of antinuclear antibody spectrum group, protein S deficiency group and antiphospholipid antibodies group were 25.0%, 22.5% and 19.4%, respectively. Each of these factors contributed 1 point to the risk score. The pregnancy loss rates were 6.3%, 24.6%, 50% for the low-, intermediate- and high-risk categories, respectively (p < .001). The area under the receiver operating characteristic curve for the score of RSA was .733. Our findings suggest that this validated and simple scoring system could accurately predict the risk of pregnancy loss of RSA patients. The score might be helpful in the selection of risk-adapted interventions to decrease the incidence. Impact StatementWhat is already known on this subject? The live birth rate increases to 80%-90% after anticoagulant and/or immunosuppressive treatment in patients with RSA. However, there is still a high rate of re-abortion even after active treatment.What do the results of this study add? Antinuclear antibody spectrum, protein s deficiency and antiphospholipid antibodies were independent risk factors for pregnancy loss. A novel predictive model based on these factors was then established and validated.What are the implications of these findings for clinical practice and/or further research? The newly developed score might be helpful in the selection of risk-adapted interventions to decrease the incidence. For patients in the intermediate-risk and high-risk groups, we should conduct more targeted studies and formulate corresponding therapies to improve the success rate of treatment.

[Prenatal diagnosis of five fetuses with 7q11.23 microdeletion or microduplication].

OBJECTIVE: To investigate the ultrasonographic findings and genetic testing methods for fetuses carrying copy number variants (CNVs) of 7q11.23 region. METHODS: Prenatal cases with 7q11.23 microdeletion/microduplication detected by single nucleotide polymorphism array (SNP array) from January 2016 to June 2020 were retrospectively analyzed, including fetal ultrasound, chromosomal karyotype, SNP array, pregnancy outcome and follow-up. Literature on 7q11.23 CNVs identified upon prenatal diagnosis was also reviewed. RESULTS: Five fetuses were found with 7q11.23 CNVs, including 3 microdeletions and 2 microduplications. Of them, 4 had ultrasonographic anomalies. The karyotypes of all fetuses were normal. Of three 7q11.23 microdeletions, two were de novo, while the remaining one couple did not accept parental verification. Of two 7q11.23 microduplications, one was de novo and the another was inherited from a phenotypic normal father. Three 7q11.23 microdeletions and one de novo 7q11.23 microduplication were electively aborted. One fetus carrying paternally inherited 7q11.23 microduplication was delivered full term. Follow-up found the infant had a normal phenotype. CONCLUSION: Fetuses with 7q11.23 microdeletions or microduplications showed phenotypic heterogeneity. SNP array can accurately detect 7q11.23 CNVs, thereby provide accurate information for prenatal diagnosis and genetic counseling.

[Study on clinical features and diagnostic methods of prenatal Wolf-Hirschhorn syndrome].

OBJECTIVE: To investigate the clinical features of fetuses with Wolf-Hirschhorn syndrome(WHS) and explore the diagnostic methods and prenatal ultrasound characteristics and provide evidence for prenatal genetic counseling. METHODS: We retrospectively analyzed 5 cases of WHS fetuses diagnosed from March 2016 to February 2020, and analyzed the results of chromosomal karyotype analysis and chromosomal microarray analysis (CMA) of the fetuses. RESULTS: Five cases of WHS were detected by CMA, four cases were detected by karyotype analysis. Prenatal ultrasound revealed 4 abnormalities, of which 3 had intrauterine growth restriction, and only 1 had abnormalities of the maxillofacial region. The sequence of the fragments was 4p16.3p16.1 with a loss of 6.5 Mb, 4p16.3p15.32 with a loss of 15.6 Mb combined with 2p25.3 increased by 906kb, 4p16.3p15.31 with a loss of 20.4 Mb, 4p16.p15.1 with a loss of 35 Mb and 4p16.3p14 with a loss of 37 Mb. CONCLUSION: Fetal growth restriction may be one of the early manifestations of WHS. Absence of fetal facial abnormality by prenatal ultrasound screening cannot exclude WHS. Karyotype analysis may miss the diagnosis of WHS, while combined CMA techniques can improve the diagnostic accuracy.

[Effectiveness of non-invasive prenatal screening for the detection of fetal sex chromosome anomalies].

OBJECTIVE: To evaluate the efficacy of non-invasive prenatal screening (NIPS) for fetal sex chromosome anomalies. METHODS: A retrospective analysis was carried out for 20 802 women undergoing NIPS screening. For 165 cases suspected for fetal sex chromosomal anomalies, the results of invasive prenatal diagnosis were obtained. RESULTS: Among the 165 cases suspected for fetal sex chromosome anomalies, 129 have accepted invasive prenatal diagnosis, and 45 were confirmed, which yielded a positive predictive value of 34.88%. These included 16 cases of 47,XYY, 10 cases of 47,XXY, 6 cases of 45,X/46,XX, 5 cases of 47,XXX, 3 cases of 45,X, 1 case of 45,X/46,X,i(X)(q10), 1 case of 45,X/46,X,del(X)(q22), 1 case of 46,X,del(X)(q22), 1 case of 46,X,del(X)(p11) and 1 case of Xp22.31 1.2 Mb deletion. CONCLUSION: NIPS has limited value for detecting fetal sex chromosome anomalies. Karyotyping analysis combined with other diagnostic techniques can offer effective prenatal diagnosis for suspected cases.

[Impact of confined placental mosaicism on non-invasive prenatal testing and pregnancy outcomes].

OBJECTIVE: To assess the impact of confined placental mosaicism (CPM) on non-invasive prenatal testing (NIPT) and pregnancy outcomes. METHODS: Copy number variation sequencing (CNV-seq) and single nucleotide polymorphism array (SNP-array) were carried out on placental specimen sampled from eight pregnancies with confirmed false-positive NIPT results. The impact of CPM on NIPT and pregnancy outcomes were analyzed based on the laboratory tests and clinical characteristics. RESULTS: Five of the eight cases with false-positive NIPT results were proven to be CPM involving trisomy 9, 13, 21, 22, and X, respectively. The mosaic ratios for different placental regions have varied from 4% to 80%. Two fetuses with confirmed CPM showed fetal growth restriction (FGR) and additional ultrasound abnormalities, 1 fetus showed only FGR. The remaining two fetuses showed normal growth. CONCLUSION: NIPT is highly sensitive to CPM, whilst CPM is an important cause for false-positive NIPT result. CPM may be associated with FGR. Investigation of the presence of CPM is important for both pre- and post-test genetic counseling and management of the pregnancy.

Chromosomal microarray analysis for pregnancies with or without ultrasound abnormalities in women of advanced maternal age.

BACKGROUND: Chromosomal microarray analysis (CMA) has been suggested to be routinely conducted for fetuses with ultrasound abnormalities (UA), especially with ultrasound structural anomalies (USA). Whether to routinely offer CMA to women of advanced maternal age (AMA) without UA when undergoing invasive prenatal testing is inconclusive. OBJECTIVE: This study aimed to evaluate the efficiency of CMA in detecting clinically significant chromosomal abnormalities in fetuses, with or without UA, of women with AMA. METHODS: Data from singleton pregnancies referred for prenatal CMA due to AMA, with or without UA were obtained. The enrolled cases were divided into AMA group (group A) and AMA accompanied by UA group (group B). Single nucleotide polymorphism (SNP) array technology and conventional karyotyping were performed simultaneously. RESULTS: A total of 703 cases were enrolled and divided into group A (N = 437) and group B (N = 266). Clinically significant abnormalities were detected by CMA in 52 cases (7.4%, 52/703; the value in group A was significantly lower than that in group B (3.9% vs 13.2%, P < .05); no statistic difference was observed with respect to submicroscopic variants of clinical significance between the two groups (0.9% vs 2.6%, P > .05). CONCLUSIONS: Chromosomal microarray analysis should be available to all women with AMA undergoing invasive prenatal testing, regardless of ultrasound findings.

[Prenatal diagnosis and clinical analysis of two fetuses with Cat-eye syndrome].

OBJECTIVE: To determine the origin of supernumerary small marker chromosomes (sSMCs) carried by two fetuses. METHODS: Single nucleotide polymorphism array (SNP-array) and fluorescence in situ hybridization (FISH) analysis were carried out on cells cultured from the amniotic fluid samples. RESULTS: SNP-array analysis showed both fetuses to be arr[hg19]22q11.1q11.21(16 888 899-18 649 190)×4, with a duplicated 1.7 Mb region (16 888 899-18 649 190) leading to partial tetrasomy of 22q11.1-22q11.21. FISH confirmed that both fetuses were 47,XN,+mar.ish idic(22)(q11.2) (RP11-958H20 ++),which suggested a diagnosis of Cat-eye syndrome (CES). The appearance of abortuses were consistent with the diagnosis of CES. CONCLUSION: Two fetuses with CES were diagnosed by genetic testing. The latter has provided a basis for genetic counseling.

Application of the BACs-on-Beads™ assay for rapid prenatal detection application of BoBs™ for PND of aneuploidies and microdeletions.

Prenatal diagnosis focuses on the detection of anatomic and physiologic problems with a foetus before birth. Karyotyping is currently considered the gold standard for prenatal diagnosis of chromosomal abnormalities, but this method can be time consuming. This study evaluated the diagnostic accuracy of the BACs-on-BeadsTM (BoBs™) assay for the rapid diagnosis of aneuploidies and microdeletions. A total of 625 samples from pregnant women in Fujian province, in southeastern China-including three chorionic villus biopsies, 523 amniotic fluid samples, and 99 umbilical-cord centesis samples-were assessed for chromosomal abnormalities by karyotyping and by the BoBs™ assay. A diagnosis was successfully achieved by karyotyping for 98.8% (618/625) and by the BoBs™ assay for 100% (625/625) of the samples. Both assays were concordant for trisomy 21 (2.72%, 17/625), trisomy 18 (1.12%, 7/625), trisomy 13 (0.48%, 3/625), and sex chromosome aneuploidies (0.8%, 5/625). Unlike karyotyping, the BoBs™ assay detected 22q11.2 microdeletion (0.64%, 4/625), 22q11.2 microduplication (0.16%, 1/625), Smith-Magenis syndrome microdeletion (0.16%, 1/625), and Miller-Dieker syndrome microdeletion (0.16%, 1/625). Thus, the BoBs™ assay is a reliable and rapid test for detecting common aneuploidies and microdeletions for prenatal diagnosis, and could be used instead of karyotyping for detection of common aneuploidies as well as to provide additional information regarding microdeletions.

[Prenatal diagnosis of a fetus with Miller-Dieker syndrome].

OBJECTIVE: To report on prenatal diagnosis of a fetus with Miller-Dieker syndrome (MDS) and explore its genotype - phenotype correlation. METHODS: Chromosome karyotyping, bacterial artificial chromosome on beads (BACs-on-Beads, BoBs), fluorescence in situ hybridization (FISH), and single nucleotide polymorphism microarray (SNP array) were applied in conjunction for the prenatal diagnosis of a fetus with abnormal ultrasound findings. RESULTS: A 17p13.3 microdeletion was detected with the BoBs assay, and the result was confirmed by FISH. With the SNP array, the deletion was mapped to chromosome 17, with its range determined to be 5.2 Mb. On high-resolution banding analysis and BoB assay, the deletion was not found in either parent. CONCLUSION: The combined use of BoBs, FISH and SNP array has enabled prenatal diagnosis of a fetus with MDS. Attention should be paid to microdeletions and microduplications which can be missed by conventional chromosomal karyotyping analysis.

Molecular spectrum of ß-thalassemia in Fujian Province, Southeastern China.

To provide basic information for ß-thalassemia (ß-thal) screening, genetic counseling and prenatal diagnosis (PND), we characterized ß-thal mutations in Fujian Province, Southeastern China. A total of 16 different ß-thal gene mutations were identified from 1058 patients. Of these, the IVS-II-654 (C>T) and codons 41/42 (-TCTT) were the most prevalent, accounting for 76.3% of the total mutations. Six gene mutations, IVS-I-1 (G>T), Cap +40 to +43 (-AAAC), codon 30 (A>G), +22 (G>A), codons 54-58 (-TTATGGGCAACCC) and the initiation codon (ATG>AGG) were characterized for the first time in the Fujian population. Furthermore, the following mutations, +22 (G >A), codon 36 (-C) and codon 30 (A>G), were identified for the first time in Chinese individuals. This was the first comprehensive mutation spectrum of ß-thal mutations studied in Fujian Province, People's Republic of China (PRC).

Molecular analysis and prenatal diagnosis of seven Chinese families with genetic epilepsy.

Introduction: Genetic epilepsy is a large group of clinically and genetically heterogeneous neurological disorders characterized by recurrent seizures, which have a clear association with genetic defects. In this study, we have recruited seven families from China with neurodevelopmental abnormalities in which epilepsy was a predominant manifestation, aiming to elucidate the underlying causes and make a precise diagnosis for the cases. Methods: Whole-exome sequencing (WES) combined with Sanger sequencing was used to identify the causative variants associated with the diseases in addition to essential imaging and biomedical examination. Results: A gross intragenic deletion detected in MFSD8 was investigated via gap-polymerase chain reaction (PCR), real-time quantitative PCR (qPCR), and mRNA sequence analysis. We identified 11 variants in seven genes (ALDH7A1, CDKL5, PCDH19, QARS1, POLG, GRIN2A, and MFSD8) responsible for genetic epilepsy in the seven families, respectively. A total of six variants (c.1408T>G in ALDH7A1, c.1994_1997del in CDKL5, c.794G>A in QARS1, c.2453C>T in GRIN2A, and c.217dup and c.863+995_998+1480del in MFSD8) have not yet been reported to be associated with diseases and were all evaluated to be pathogenic or likely pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Methods: Based on the molecular findings, we have associated the intragenic deletion in MFSD8 with the mutagenesis mechanism of Alu-mediated genomic rearrangements for the first time and provided genetic counseling, medical suggestions, and prenatal diagnosis for the families. In conclusion, molecular diagnosis is crucial to obtain improved medical outcomes and recurrence risk evaluation for genetic epilepsy.

Molecular characterization of a novel 27.6-kb deletion causing α(+) thalassemia in a Chinese family.

Over 80% of the α-thalassemia cases in southern China are caused by large deletions involving the α-globin gene cluster on chromosome 16p13.3. Here, we characterized a novel 27.6-kb deletion on the α-globin gene cluster in a Chinese family. Its breakpoints were detected to lie between coordinates 9079 and 36718 of the α-globin gene cluster (NG_000006.1), with a total of 27,640 nucleotides deleted. It was designated as -α (27.6) deletion. The proband is a compound heterozygote of --(SEA) and -α (27.6) and he displayed very mild hemoglobin H disease phenotype with Hb 7.9-9.3 g/dl. Phenotypic analysis on heterozygote of this deletion revealed it as α(+) mutation. It leads to a very mild phenotype as adult heterozygotes have normal hematological parameters with the values at the lower border of the normal range. RT-PCR analysis showed that the α-globin mRNA level of the heterozygotes was decreased when compared with that of normal people.

Comprehensive Assessment of Fetal Bilateral Ventriculomegaly Based on Genetic Disorders, Cytomegalovirus Infection, Extra Prenatal Imaging and Pregnancy Outcomes in a Tertiary Referral Center.

OBJECTIVE: This retrospective study aimed to systematically evaluate the genetic disorders, cytomegalovirus (CMV) infection, extra ultrasound findings and outcomes of fetuses with bilateral ventriculomegaly (BVM). METHODS: Data from pregnancies with fetal BVM were obtained between 2014 and 2020. The cases were divided into groups of isolated bilateral ventriculomegaly (IBVM) and non-isolated bilateral ventriculomegaly (NIBVM) according to the presence of extra prenatal imaging. Subgroups of mild, moderate, and severe were determined according to lateral ventricle widths. The NIBVM group was further classified into pregnancies with soft markers, non-structural abnormalities, and structural abnormalities. RESULTS: A total of 353 pregnancies were enrolled, including 153 cases of IBVM and 200 cases of NIBVM. Conventional karyotyping was performed on 192 samples, and 15 cases of numerical abnormalities and 3 cases of unbalanced structural abnormalities were identified. Chromosomal microarray analysis (CMA) was concurrently performed on 108 of them and revealed additional 5 cases (4.7%) of copy number variants with clinical significance. CMV DNA testing was performed on 154 of the 192 cases that underwent invasive prenatal diagnosis, and a positive result was found in 2 (1.3%) cases. In the IBVM group, the percentage of favorable prognosis in the mild, moderate and severe pregnancies were 94.4%, 79.2%, and 4.8%, respectively, and the termination of pregnancy (TOP) rates were 4.6%, 20.8%, and 85.7%, respectively. In both the mild and moderate NIBVM, the TOP rates progressively increased and the favorable prognosis survival rates progressively decreased relative to the soft markers, non-structural abnormalities, and structural abnormalities, respectively. Approximately 94.1% of severe NIBVM ended in termination. CONCLUSION: Genetic disorders and fetal infection are important etiology of BVM. CMA is highly recommended for genetic disorders' evaluation. Pregnancies with severe BVM always ended in TOP, while in mild-to-moderate NIBVM, prenatal imaging by ultrasound and/or MRI plays important roles in the pregnancy outcomes.

Comprehensive analysis of early pregnancy loss based on cytogenetic findings from a tertiary referral center.

BACKGROUND: Pregnancy loss is one of the most common complications during pregnancy. Clinical consultation based on etiology analysis are critical for reducing anxiety and distress. This study aimed to perform a comprehensive analysis for products of conception (POC) in miscarriage based on genetic etiology and clinical information. METHODS: A retrospective study was conducted according to cytogenetic findings of 1252 POC from spontaneous pregnancy loss over 11 years. The frequencies and profiles of chromosomal abnormalities were discussed according to the classification of women with different maternal ages, previous miscarriage history, normal live birth history, and different modes of conception. RESULTS: A total of 667 (53.2%) chromosomal abnormalities were observed, including 592 (47.3%) cases of numerical abnormalities, 38 (3.0%) cases of structural abnormalities, and 37 (3.0%) cases of mosaic aberrations. In women above 40 years of age, the rates of chromosomal abnormalities and viable autosomal trisomy were significantly higher than those in women with ≤ 29, 30-34, and 35-39 years of age (p < 0.05). The frequency of abnormal karyotype in women with normal live birth history was 61.1%, significantly higher than 52.5% in women without normal live birth history (p < 0.05). There was no significant differences among women without, with 1-2, and ≥ 3 previous miscarriages regarding the rate of abnormal karyotype (p > 0.05); viable autosomal trisomy was less common in women with ≥ 3 previous miscarriages than women with < 3 miscarriages. The frequency of chromosomal abnormalities was 49.0% and 55.0% in women with assisted conception and natural conception (p > 0.05), respectively; monosomy X was more frequently detected in women with natural conception than assisted conception. CONCLUSION: The frequencies and profiles of chromosomal abnormalities in early miscarriages are strongly associated with clinical information including maternal age, previous miscarriage, live birth history, and mode of conception. Cytogenetic analysis of POC should be recommended to women with a first miscarriage and women with normal live birth history.

Diagnostic accuracy and value of chromosomal microarray analysis for chromosomal abnormalities in prenatal detection: A prospective clinical study.

ABSTRACT: Chromosomal microarray analysis (CMA) has emerged as a primary diagnostic tool for the evaluation of developmental delay and structural malformations in children. The aim of this study was to compare the accuracy and value of CMA and karyotyping on diagnosis of chromosomal abnormalities in Fujian province of South China.In the study, 410 clinical samples were collected from pregnant women between March 2015 and December 2016, including 3 villus (0.73%, 3/410), 296 amniotic fluid (72.20%, 296/410), and 111 umbilical cord blood (27.07%, 111/410). All samples were screening for chromosomal abnormalities by both using CMA and karyotyping.The success rate of CMA and karyotyping was 100% (410/410) and 99.27% (407/410), respectively. Sixty-one (14.88%, 61/410) samples were presented with chromosomal abnormalities by using CMA, whereas 47 (11.55%, 47/407) samples were shown with chromosomal abnormalities by using karyotyping. Thirty-one (8.61%, 31/360) samples with normal karyotypes were found to exist chromosomal abnormalities by using CMA. Receiver operating characteristic analysis showed that the area under the curve of karyotyping on the diagnosis of chromosomal abnormalities was 0.90 (95% confidence interval: 0.87-0.93), the sensitivity and specificity was 87.56% and 91.22%, respectively. The area under the curve of CMA on the diagnosis of chromosomal abnormalities was 0.93 (95% confidence interval: 0.90-0.95), with 90.68% sensitivity and 94.40% specificity. Notably, the combination of CMA and karyotyping could improve the diagnosis of chromosomal abnormalities.CMA has a better diagnostic value for screening chromosomal abnormalities, especially for those pregnant women with normal karyotypes. This study has guiding value for prenatal diagnosis in Fujian province of South China.

A new ß-thalassemia deletion mutation [codon 36 (-C)] observed in a Chinese woman.

In this study we present the first report of the detection of a new ß-thalassemia (ß-thal) mutation at codon 36 (-C) in the Chinese population. This frameshift mutation generates a TGA stop codon at position 60, resulting in a thalassemia phenotype. This is the first example of a premature stop codon at position 60 because of codon 36. The characterization of uncommon mutations is useful for the screening of ß-thal carriers, genetic counseling and prenatal diagnosis.

Single nucleotide polymorphism array analysis of 102 patients with developmental delay and/or intellectual disability from Fujian, China.

Developmental delay/intellectual disability (DD/ID) is a complex and phenotypically heterogeneous neurodevelopmental disorder characterized by significant deficits in cognitive and adaptive skills, debuting during the developmental period. In this study, we evaluated the usefulness of single nucleotide polymorphism (SNP) array in the detection of genetic causes of 102 DD/ID patients from Fujian (China). Of them, clinically relevant variants (including pathogenic and likely pathogenic), variants of uncertain significance (VOUS), and no clinically relevant variants (including likely benign and benign) were detected in 19, 4 and 79 patients, accounting for 18.6%, 3.9% and 77.5%, respectively, with a diagnostic yield of 18.6% in our study. Furthermore, we divided 19 clinically relevant variants into 4 groups, including chromosome aneuploidy (n = 1); large copy number variants (CNVs) (>10 Mb) (n = 8); known genomic disorders (n = 8), and likely pathogenic CNVs (n = 2). Moreover, we discussed our findings with respect to 4 cases of VOUS. Overall, we confirmed that DD/ID is a genetically heterogeneous condition and emphasized the importance of using genome-wide SNP array in the detection of its genetic causes. Additionally, we provided clinical and molecular data of patients with causal chromosomal aberrations, and discussed the potential implication in DD/ID of genes located within those CNVs or regions of homozygosity.

LZAP promotes the proliferation and invasiveness of cervical carcinoma cells by targeting AKT and EMT.

Objective: To explore the relationship and mechanism of LZAP in the occurrence and development of cervical cancer and to provide a new target and intervention method for the treatment of cervical cancer. Methods: Data mining and analysis of LZAP expression levels were performed using several online databases, including The Cancer Genome Atlas (TCGA). A cervical cancer cell line that stably overexpresses LZAP was established, and the effect of LZAP overexpression on cell proliferation, invasion, migration and tumor formation in vivo as well as its mechanism were explored. Results: Our study shows that the expression of LZAP is upregulated in cervical cancer. The overexpression of LZAP can significantly promote the proliferation, colony formation, and invasion and migration abilities of cervical cancer cells. The tumorigenesis test in nude mice showed that overexpression of LZAP could promote the tumorigenicity of cervical cancer cells in vivo. LZAP could also promote the phosphorylation of AKT at position 473 and the epithelial-mesenchymal transition (EMT). Conclusion: The expression of LAZP is increased in cervical cancer, which can enhance the invasion, metastasis, and EMT in cervical cancer cells by promoting AKT phosphorylation.

Long-Molecule Sequencing: A New Approach for Identification of Clinically Significant DNA Variants in α-Thalassemia and ß-Thalassemia Carriers.

Multiple molecular tests are currently needed for accurate carrier testing for thalassemia. Therefore, long-molecule sequencing (LMS) was evaluated as an alternate on the PacBio Sequel platform for genotyping carriers of α-thalassemia or ß-thalassemia. Multiplex long PCR was used to generate representative amplicons for the α (HBA1/2) and ß (HBB) gene loci. Following LMS, circular consensus sequencing reads were aligned to the hg19 reference genome and variants called using FreeBayes software version 1.2.0. In a blinded study of 64 known carrier samples, all HBA1/2 and HBB variants detected by LMS were concordant with those independently assigned by targeted PCR assays. For HBA1/2 carrier samples, LMS accurately detected the common South East Asian, -α3.7, and -α4.2 deletions and four different rare single-nucleotide variants (SNVs). For HBB carrier samples, LMS accurately detected the most common Chinese insertion and deletion variant c.126_129delCTTT and 14 different SNVs/insertions and deletions and could discriminate compound heterozygous SNVs (trans configuration) and identify variants linked to benign SNPs (cis configuration). Overall, LMS displayed the hallmarks of a scalable, accurate, and cost-effective genotyping method. With further test coverage to additionally include detection of other clinically significant HBA1/2 copy number variations, such as the Thai, Mediterranean, and Filipino deletions, LMS may eventually serve as a comprehensive method for large-scale thalassemia carrier screening.

Identification of a novel pre-terminating mutation in human HBB gene as a cause of ß0-thalassemia phenotype.

Beta (ß)-thalassemia (thal) is one of the most common genetic disorders of hemoglobin synthesis worldwide. Most cases of ß-thal are caused by point mutations in hemoglobin subunit beta (HBB) gene, and only a minority of cases are caused by missing mutations of HBB gene. In this study, a 31-year-old pregnant woman with a typical thal phenotype was admitted at Fujian Provincial Maternity and Children's Hospital for prenatal diagnosis. Her father also presented with a typical thal phenotype, while the other members in the proband family were normal. Interestingly, Gap-PCR and reverse dot-blot hybridization assays showed that no mutation was found in the human HBA and HBB genes of the proband and her father. Subsequently, Sanger DNA sequencing identified a novel pre-terminating mutation, c.271 G>T [CD90 (GAG>TAG, Glu→stop codon)], in HBB gene from the proband and her father, while the other members in the proband family were normal. This mutation created a stop codon at amino acid 90 in exon 2 coding sequences of HBB gene, and led to a ß0-thal phenotype. In summary, the present study is, to the best of our knowledge, the first to report a pre-terminating mutation, c.271 G>T [CD90 (GAG>TAG, Glu→stop codon)], in human HBB gene as a cause of ß0-thal phenotype. This is important for clarifying the molecular mechanism of ß0-thal and is useful for genetic counseling and prenatal screening.