Prenatal genetic diagnosis of fetuses with dextrocardia using whole exome sequencing in a tertiary center.

To evaluate the genetic etiology of fetal dextrocardia, associated ultrasound anomalies, and perinatal outcomes, we investigated the utility of whole exome sequencing (WES) for prenatal diagnosis of dextrocardia. Fetuses with dextrocardia were prospectively collected between January 2016 and December 2022. Trio-WES was performed on fetuses with dextrocardia, following normal karyotyping and/or chromosomal microarray analysis (CMA) results. A total of 29 fetuses with dextrocardia were collected, including 27 (93.1%) diagnosed with situs inversus totalis and 2 (6.9%) with situs inversus partialis. Cardiac malformations were present in nine cases, extra-cardiac anomalies were found in seven cases, and both cardiac and extra-cardiac malformations were identified in one case. The fetal karyotypes and CMA results of 29 cases were normal. Of the 29 cases with dextrocardia, 15 underwent WES, and the other 14 cases refused. Of the 15 cases that underwent WES, clinically relevant variants were identified in 5/15 (33.3%) cases, including the diagnostic variants DNAH5, DNAH11, LRRC56, PEX10, and ZIC3, which were verified by Sanger sequencing. Of the 10 cases with non-diagnostic results via WES, eight (80%) chose to continue the pregnancies. Of the 29 fetuses with dextrocardia, 10 were terminated during pregnancy, and 19 were live born. Fetal dextrocardia is often accompanied by cardiac and extra-cardiac anomalies, and fetal dextrocardia accompanied by situs inversus is associated with a high risk of primary ciliary dyskinesia. Trio-WES is recommended following normal karyotyping and CMA results because it can improve the diagnostic utility of genetic variants of fetal dextrocardia, accurately predict fetal prognosis, and guide perinatal management and the reproductive decisions of affected families.

Genetic testing for fetal loss of heterozygosity using single nucleotide polymorphism array and whole-exome sequencing.

The study explored the clinical significance of fetal loss of heterozygosity (LOH) identified by single-nucleotide polymorphism array (SNP array). We retrospectively reviewed data from pregnant women who underwent invasive diagnostic procedures at prenatal diagnosis centers in southeastern China from December 2016 to December 2021. SNP array was performed by the Affymetrix CytoScan 750 K array platform. Fetuses with LOH were further identified by parental verification, MS-MLPA, and/or trio whole-exome sequencing (trio-WES). The genetic results, fetal clinical manifestations, and perinatal outcome were analyzed. Of 11,062 fetuses, 106 (0.96%) had LOH exhibiting a neutral copy number, 88 (83.0%) had LOH in a single chromosome, whereas 18 (17.0%) had multiple LOHs on different chromosomes. Sixty-six fetuses had ultrasound anomalies (UAs), most frequently fetal growth restriction (18/66 (27.3%)). Parental SNP array verification was performed in 21 cases and trio-WES in 21 cases. Twelve cases had clinically relevant uniparental disomy, five had pathogenic variants, four had likely pathogenic variants, six had variants of unknown significance, and eight had identity by descent. The rate of adverse pregnancy outcomes in fetuses with LOH and UAs (24/66 (36.4%)) was higher than in those without UAs (6/40 (15.0%)) (p < 0.05). LOH is not uncommon. Molecular genetic testing techniques, including parental SNP array verification, trio-WES, methylation-specific multiplex ligation-dependent probe amplification, regular and systematic ultrasonic monitoring, and placental study, can accurately assess the prognosis and guide the management of the affected pregnancy.

First Report of Filipino ß0-Thalassemia/ß-Thalassemia in a Chinese Family.

A pregnant woman living in Fujian Province, southeastern China, presented due to a risk of having a baby with ß-thalassemia major, during her second pregnancy, since she and her husband were suspected as ß-thalassemia carriers and their affected daughter was a transfusion-dependent patient. Using the common α-thalassemia and ß-thalassemia genotypes test, the pregnant woman was diagnosed as a ß-thalassemia carrier with ßIVS-2 - 654 (C→T)/ßN genotype and her daughter had a homozygosity for IVS - 2 - 654 (C→T) mutation, however, no abnormalities were detected in her husband. SMRT identified a Filipino ß0-deletion in her husband, and MLPA also revealed an unknown deletion in the HBB gene. Electrophoresis showed approximately 350 bp of the PCR product, and the ß-Filipino genotype presented novel fracture fragments ranging from 5,112,884 to 5,231,358 bp, and lacked a 118,475 bp fragment relative to the wild-type sequence. The daughter was therefore diagnosed with the ßIVS-2 - 654 (C→T)/ßFilipino genotype. Prenatal diagnosis with umbilical cord blood at 27th week of gestation showed heteroztgosity for IVS - 2 - 654 (C→T) mutation in the fetus and continued pregnancy was recommended. In conclusion, we identified the Filipino ß0-deletion in a Chinese family, from Fujian area, for the first time, during prenatal screening.

Mutation analysis of GJB2, SLC26A4, GJB3 and mtDNA12SrRNA genes in 251 non-syndromic hearing loss patients in Fujian, China.

OBJECTIVES: The molecular etiology of non-syndromic hearing loss (NSHL) in Southeastern China (Fujian) has not been precisely identified. our study selected patients with NSHL and analyzed their causative genes, which helped to improve the accuracy of the diagnosis of hereditary hearing loss (HHL) and its treatment. METHODS: 251 unrelated patients who attended the otolaryngology clinic of Fujian Maternal and Child Health Hospital with hearing loss were enrolled to our study. All patients had genetic tests and listening tests, of which 251 were diagnosed with NSHL. In addition, we used whole-exome sequencing (WES) in a patient who has a significant family history of HHL but negative for gene chip testing, as well as in his family members. RESULT: Among of 251 patients, Nucleotide changes were found in 63 cases (25.09%), including 34 located in GJB2(13.5%, including 235delC and 299_300delAT), 13 located in SLC26A4(5.18%, including c.919-2G > A and 2168 A > G), 1 located in GJB3(0.4%,538C > T) and 16 located in mtDNA12SrRNA (6.37%,1555 A > G). In addition, we discuss the process of identifying novel PLS1 mutations from 251 patients. CONCLUSION: Our results demonstrate the conventional deafness gene mutation in 251 NSHL patients in Fujian, China. Compared with the other area of China, we have a lower detection rate, but GJB2 235delC remains the most common mutation in Fujian. In addition, we discuss the process of discovering novel mutation locus for deafness, which provides an understanding for deafness diagnosis and genetic testing.

The clinical value of hsa-miR-190b-5p in peripheral blood of pediatric ß-thalassemia and its regulation on BCL11A expression.

BACKGROUND: The B cell CLL/lymphoma 11A (BCL11A) is a key regulator of hemoglobin switching in ß-thalassemia (ß-thal). Previous study has suggested that dysregulated microRNAs are involved in the regulation of BCL11A expression. The aim of this study was to investigate the clinical value of hsa-miR-190b-5p in ß-thal, and to confirm the regulatory effect of hsa-miR-190b-5p on BCL11A expression. METHODS: The peripheral blood of 25 pediatric ß-thal patients and 25 healthy controls were selected, and qRT-PCR was used to analyze the levels of hsa-miR-190b-5p and BCL11A mRNA. The relationship between hsa-miR-190b-5p expression and hematological parameters was assessed by Pearson's correlation test. The diagnostic power of hsa-miR-190b-5p was evaluated by ROC curves analysis. The direct integration between hsa-miR-190b-5p and BCL11A 3'-UTR was confirmed by luciferase reporter assay. RESULTS: Hsa-miR-190b-5p expression in pediatric ß-thal was upregulated, and negatively correlated with the MCH and HbA levels, but positively correlated with the HbF level. Hsa-miR-190b-5p showed a good diagnostic capability for pediatric ß-thal equivalent to that of HbA2 (AUC: 0.760 vs. 0.758). Moreover, the levels of BCL11A mRNA in pediatric ß-thal were decreased, and hsa-miR-190b-5p had a negative correlation with BCL11A mRNA expression (r = -0.403). BCL11A was a target gene of hsa-miR-190b-5p. The mRNA and protein levels of BCL11A were diminished by introduction of hsa-miR-190b-5p, whereas its expression was upregulated by knockdown of hsa-miR-190b-5p. CONCLUSIONS: Hsa-miR-190b-5p expression was upregulated in pediatric ß-thal and might be an effective diagnostic biomarker. BCL11A was negatively regulated by hsa-miR-190b-5p, which might provide new target for the treatment of pediatric ß-thal.

Identification of a novel 91.5 kb-deletion (αα)FJ in the α-globin gene cluster using single-molecule real-time (SMRT) sequencing.

OBJECTIVES: To present a novel 91.5-kb deletion of the α-globin gene cluster (αα)FJ identified by genetic assay and prenatal diagnosis in a Chinese family. SUBJECTS AND METHODS: The proband was a 34-year-old G3P1 (Gravida 3, Para 1) female at the gestational age of 21+ weeks with a history of an edematous fetus. A routine genetic assay (reverse dot blot hybridization, RDB) was performed to detect common thalassemia mutations. Multiplex ligation-dependent probe amplification (MLPA) and single-molecule real-time technology (SMRT) were used to detect rare thalassemia mutations. RESULTS: The hematological phenotypes of the proband, her mother, elder sister, husband, daughter, and nephew were consistent with the phenotype of α-thalassemia trait. No mutations were found in these family members by RDB, except for the proband's husband who carried an α-globin gene deletion --SEA/αα. MLPA results showed that the proband and other α-thalassemia-suspected relatives had heterozygous deletions around the POLR3K-3-463nt, HS40-178nt, and HBA-HS40-382nt probes. The 5'-breakpoint was out of probe scope and could not be determined. SMRT was performed and a 91.5-kb deletion (NC_000016.10: g.39268_130758del) in the α-globin gene cluster (αα)FJ was identified in the proband and other suspected relatives, which could explain their phenotypes. At the proband's gestational age of 22+ weeks, an amniotic fluid sample was collected and analyzed. As only the 91.5-kb deletion (αα)FJ was identified in the fetus with RDB, MLPA, and SMRT. The proband was suggested to continue the pregnancy. CONCLUSION: We first reported a 91.5-kb deletion (NC_000016.10: g.hg38-chr16:39268-_130758del) of the HS-40 region in the α-globin gene cluster (αα)FJ identified in a Chinese family. Since the HS-40 loss of heterozygosity in combination with the heterozygous deletion --SEA might result in Hb Bart's hydrops fetalis, routine genetic assay, and SMRT were recommended to individuals at risk for prenatal diagnosis.

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.

A novel PLS1 c.981+1G>A variant causes autosomal-dominant hereditary hearing loss in a family.

The fimbrin protein family contains a variety of proteins, among which Plastin1 (PLS1) is an important member. According to recent studies, variations in the coding region of the PLS1 gene are associated with the development of deafness. However, the molecular mechanism of deafness caused by PLS1 gene variants remains unknown. Whole-exome sequencing was performed on hearing-impaired family members and hearing family members to identify pathogenic variants, followed by Sanger sequencing. A minigene assay was conducted to investigate the effect of the variant on PLS1 mRNA splicing. The pathogenicity of the variant was further investigated in zebrafish. RNA-sequencing (RNA-seq) was performed to analyze the dysregulation of downstream signaling pathways caused by knockdown of PLS1 expression. We identified a novel variant, PLS1 c.981+1G>A, in a large Chinese family with hearing loss and showed that the variant is responsible for the occurrence of hearing loss by inducing exon 8 skipping. The variant caused abnormal inner ear phenotypes, characterized by decreases in the mean otolith distance, anterior otolith diameter, posterior otolith diameter, cochlear diameter, and swimming speed and distance in zebrafish. Furthermore, silencing PLS1 expression significantly upregulated the expression of genes in the PI3K-Akt signaling pathway, including Col6a3, Spp1, Itgb3 and hepatocyte growth factor (Hgf). PLS1 c.981+1G>A is a novel pathogenic variant causing hearing loss by inducing exon 8 skipping. Upregulation of the expression of genes in the PI3K-Akt signaling pathway plays an important role in the pathogenesis caused by variants in the PLS1 gene.

Application of the Single-Molecule Real-Time Technology (SMRT) for Identification of HKαα Thalassemia Allele.

OBJECTIVE: Single-molecule real-time technology (SMRT) is a sequencing technology using the DNA polymerases and fluorescently tagged nucleotides to accurately sequence DNA strands. The purpose of this study was to evaluate the detection accuracy of SMRT for identification of the Hong Kongαα (HKαα) thalassemia allele. METHODS: We conducted a blinded study of 33 samples of known HKαα alleles. These alleles were detected using SMRT to evaluate accuracy. RESULTS: We conducted a blinded study of 33 known HKαα samples and found all HKαα variants detected by SMRT to be concordant with those independently assigned by gap-polymerase chain reaction (gap-PCR), reverse dot blot hybridization, and 2-round nested PCR. In addition, SMRT detected 2 ß-thalassemia variants that were missed by conventional techniques. CONCLUSION: The results demonstrate that SMRT offers a higher detection accuracy of thalassemia rare and new loci. It is an efficient, reliable, and broad-spectrum test that can be widely used for thalassemia screening in the clinic.

Clinical findings and genetic analysis of patients with copy number variants involving 17p13.3 using a single nucleotide polymorphism array: a single-center experience.

BACKGROUND: 17p13.3 microdeletions or microduplications (collectively known as copy number variants or CNVs) have been described in individuals with neurodevelopmental disorders. However, 17p13.3 CNVs were rarely reported in fetuses. This study aims to investigate the clinical significance of 17p13.3 CNVs with varied sizes and gene content in prenatal and postnatal samples. METHODS: Eight cases with 17p13.3 CNVs out of 8806 samples that had been subjected to single nucleotide polymorphism array analysis were retrospectively analyzed, along with karyotyping, clinical features, and follow-up. RESULTS: Eight cases with 17p13.3 CNVs consisted of five fetuses, one aborted embryo and two probands manifested severe congenital defects. The indications of prenatal testing varied considerably for the five fetuses, including ultrasound abnormalities (n = 3), segmental deletions indicated by non-invasive prenatal testing (n = 1), and intellectual disability in the mother of one fetus (n = 1). Of them, two and six harbored copy number gains and losses involving 17p13.3, respectively. The size of the detected 17p13.3 CNVs ranged from 576 kb to 5.7 Mb. Case 1 was diagnosed with 17p13.3 duplication syndrome, and cases 4, 6, and 7 with Miller-Dieker syndrome (MDS). Microdeletions of the 17p13.3 region in two cases (cases 5 and 8) involving YWHAE and CRK, sparing PAFAH1B1, were classified as pathogenic. Case 2 harbored a 576 kb microduplication, encompassing YWHAE and CRK but not PAFAH1B1, which was of maternal origin and considered a variant of uncertain significance. Case 3 carried one 74.2 Mb mosaic duplication of approximately 3.5 on chromosome 17p13.2q25.3, and two deletions at 17p13.3p13.2 and 17q25.3. The karyotype of case 3 was 46,XY,r(17)(p13q25). For five fetuses, only case 2 continued gestation and showed normal development at the age of 15 months; the others were subjected to termination of pregnancy. CONCLUSION: The clinical findings of 17p13.3 microdeletions or microduplications varied among subjects, and 17p13.3 CNVs often differ in size and gene content. Microdeletions or microduplications containing the typical MDS region, as well as the microdeletions involving YWHAE and CRK, could be classified as pathogenic. The clinical significance of small duplications including YWHAE and CRK but not PAFAH1B1 remains uncertain, for which parental testing and clinical heterogeneity should be considered in genetic counseling.

Analysis of genotype-phenotype correlation in patients with α-thalassemia from Fujian province, Southeastern China.

BACKGROUND: There is a high carrying rate of α-thalassemia in Fujian province. However, there are few large-scale studies on the correlation between genotype and phenotype in Fujian province. The purpose of this study was to analyze the phenotype and genotype in a cohort of 2923 patients with α-thalassemia in Fujian province, so as to provide reference data for screening and diagnosis of α-thalassemia in Fujian province. METHODS: The genotype of α-thalassemia was detected by PCR reverse dot blot assay, gap-PCR, single PCR, nested PCR, and sequencing. Clinical and hematological indices of 2923 patients were collected, and the correlation between genotype and phenotype was analyzed. RESULTS: Among 10,350 patients, 2923 cases were found with α-thalassemia, with a detection rate of 28.24%. Among them, --SEA /αα was the most common genotype, accounting for 64.80%. In addition, rare α-thalassemia genotypes were detected in Fujian province, including --THAI /αα (0.41%), HKαα/--SEA (0.03%), and the novel α-thalassemia gene mutation CD5 (GCC>ACC) (HGVS named HBA1: c.16G>A) (0.03%). Patients with deletional genotypes of α-thalassemia were found to have higher RBC and lower Hb, MCV, MCH, and HbA2 than patients with non-deletional genotypes of α-thalassemia (p < 0.05). CONCLUSION: The clinical phenotype of α-thalassemia is influenced by molecular mechanisms. HBA1: c.16G>A mutation is a novel mutation that was first reported in Fujian province, which enriches the human hemoglobin mutation spectrum.

Prenatal diagnosis of fetuses with region of homozygosity detected by single nucleotide polymorphism array: a retrospective cohort study.

Region of homozygosity (ROH) is classified as uniparental disomy (UPD) or identity by descent, depending on its origin. To explore the clinical relevance of ROH in prenatal diagnoses, we reviewed 5063 fetal samples subjected to single nucleotide polymorphism array at our center over 5 years. ROH cases meeting our reporting threshold were further analyzed. ROHs were detected in 22 fetuses (0.43%, 22/5063), of which, 77.3% (17/22) showed a ROH on a single chromosome and 22.7% (5/22) showed multiple ROHs on different chromosomes. Among 5063 fetuses undergoing invasive prenatal diagnoses owing to various indications, five cases were identified as UPDs with a rate of ~1/1000. We observed clinically relevant UPDs in two cases related to Prader-Willi syndrome and transient neonatal diabetes mellitus. Of note, one case showed 50% mosaicism for trisomy 2 in amniotic fluid, whereas a complete UPD (2) was observed in umbilical cord blood. Trio whole-exome sequencing was performed for three cases. Clinically relevant variants were identified in two cases, one of which, NM_000302:c.2071_2072insCC (p.R693Qfs*122) in PLOD1 located in the ROH, may be related to Ehlers-Danlos syndrome, kyphoscoliotic type, 1. Overall, 72.7% (16/22) of the ROH carriers showed ultrasound abnormalities, of whom eight (50%, 8/16) had adverse perinatal outcomes. Our study demonstrates that the clinical relevance of ROHs should be examined regarding fetuses with ROHs occurring on imprinted chromosomes or those derived from consanguineous parents in prenatal diagnoses; imprinting disorders and/or autosomal recessive diseases attributed to ROHs should be considered during genetic counseling.

Application of the prenatal BACs-on-Beads™ assay for rapid prenatal detection of sex chromosome mosaicism.

The prenatal BACs-on-Beads™ (BoBs) assay was introduced for rapid detection of abnormalities of chromosomes 13, 18, 21, X, and Y and specific nine significant microdeletion syndromes. The ability of prenatal BoBs to detect mosaicism ranged from 20 to 40%. However, there have been no prenatal studies of sex chromosome mosaicism in prenatal BoBs. Therefore, the present study was performed with an aim to uncover the detection level of sex chromosome mosaicism that application of prenatal BoBs assay, and then to assess the sensitivity of prenatal BoBs assay, thereby improving the prenatal diagnostic accuracy. A total of 31 samples of amniotic fluid (AF) and umbilical cord blood (UCB) for prenatal diagnosis were collected, and the results were confirmed through karyotyping, single nucleotide polymorphism microarray (SNP-array) and copy number variation sequencing (CNV-seq). 23 cases of sex chromosome mosaicism were prompted abnormal by prenatal BoBs, the minimum detection level of mosaicism was about 6% as detected by karyotype. The overall sensitivity of prenatal BoBs in the detection of sex chromosome mosaicism was 74.2% (23/31). This study evaluated the effectiveness of prenatal BoBs for detecting sex chromosome mosaicism in prenatal diagnosis, and the results will provide valuable information for genetic counseling.

Genetic research and clinical analysis of ß-globin gene cluster deletions in the Chinese population of Fujian province: A 14-year single-center experience.

BACKGROUND: Heterozygotes of HPFH and 뫧 thalassemia are clinically asymptomatic or have mild hemoglobin (Hb) values. However, when both HPFH and δß-thalassemia are coinherited with heterozygous ß-thalassemia, patients may progress to a clinical phenotype of thalassemia intermedia or thalassemia major. The purpose of this study was to characterize the genotypes and analyze the phenotypes of these disorders in Fujian Province, to offer advice for genetic counseling and accurate prenatal diagnosis in this region. A total of 55 001 subjects were participated in thalassemia screening. 142 subjects with HbF levels ≥10%, before the blood transfusion, were selected for further investigation. METHODS: Multiplex ligation-dependent probe amplification (MLPA) and Gap-PCR were used to screen for three ß-globin gene cluster deletions: Chinese G γ(A γδß)0 thalassemia and Southeast Asia HPFH (SEA-HPFH) deletion and 1357 bp deletion (NG-000007.3:g.69997-71353 del 1357). RESULTS: A total of 142 patients with HbF (≥10%) were enrolled to characterize the molecular basis of ß-globin gene cluster deletions in our study; 22 cases 0.04% (22/55 001) were definitively diagnosed with ß-globin gene cluster deletions. Ten cases were heterozygous for the Chinese G γ(A γδß)0 -thal mutations, 10 cases were heterozygous for SEA-HPFH, and one case was compound heterozygous for SEA-HPFH and the α-thal mutation. The 1357 bp deletion (NG-000007.3:g.69997-71353 del 1357) was detected in one case. Moreover, the hemoglobin A2  levels in patients who were heterozygous for Chinese G γ(A γδß)0 -thal were statistically lower than in cases with SEA-HPFH deletion(p < 0.05). CONCLUSION: In Fujian Province, the prevalence of common ß-globin gene cluster deletions was 0.04%. What's more, the most common ß-globin cluster deletions are the Chinese G γ(A γδß)0 and SEA-HPFH.

[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.

Prenatal diagnosis of thalassemia in 695 pedigrees from southeastern China: a 10-year follow-up study.

Thalassaemia is highly prevalent in southeastern China. This 10-year follow-up study aimed to characterize the genotype and karyotype of thalassaemia in fetal samples derived from thalassemia carriers in Fujian province, southeastern China. A total of 476 prenatal samples from 472 couples carrying α-thalassaemia traits and 224 samples from 223 couples carrying ß-thalassaemia traits were collected for STR analysis, detection of thalassemia genotypes and karyotyping. The common deletional α-thalassemias and rare thalassemia genotypes were detected using Gap-PCR assay, and the common ß-globin gene mutations were detected using PCR-RDB assay. We detected 43.49% prevalence of α-thalassaemia minor, 26.05% prevalence of α-thalassaemia intermediate and major and 1.89% prevalence of rare form among the 476 prenatal samples from couples with α-thalassaemia, and 85 fetuses with ß-thalassemia heterozygote, 16 with homozygote and 21 with double heterozygote, and a rare ßIVS-2-654(C→T) /Chinese Gγ (A γδß)0  genotype among the 224 prenatal samples from couples with ß-thalassemia. Karyotyping showed 7 fetuses with abnormal karyotypes. Totally 153 pregnancies were terminated, and genetic diagnosis of thalassemia using fetal umbilical cord blood following induction of labor showed consistent results with prenatal diagnosis. No thalassemia phenotypes were identified in normal infants half a year after birth, and the infants with α-thalassemia and ß-thalassemia minor had no or mild anemia symptoms, but normal development, while 15 babies with hemoglobin H disease presented moderate anemia symptoms. Our data suggest the pregestational screening of thalassemia, notably compound and rare forms of thalassemia, for couples carrying thalassemia traits.

[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.

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.

First report of the spectrum of δ-globin gene mutations among women of reproductive age in Fujian area-Discrimination of δ-thalassemia, α-thalassemia, and Iron Deficiency Anemia.

BACKGROUND: Low HbA2 level is an underlying of δ-thalassemia, α-thalassemia, and IDA. Interactions of these disorders can generate a wide spectrum of phenotype, which will pose diagnostic conundrum for clinical assessment, carrier screening, and genetic counseling. METHODS: Subjects with HbA2 levels below 2.0% with normal or reduced hematological parameters were recruited for further investigation. δ-globin gene mutations were identified by DNA sequencing of the HBD gene. Serum ferritin (SF) concentration was determined by the chemiluminescent microparticle immunoassay. The three common deletional α-thalassemia (--SEA /αα, -α3.7 /αα, and -α4.2 /αα) were detected using Gap-PCR, detection of the point mutations in the three nondeletional α-thalassemia (αCS α/αα,αQS α/αα,αWS α/αα), and the 17 common ß-thalassemia was performed using reverse dot blot hybridization (RDB). RESULTS: We had characterized the δ-globin gene mutations in 20 cases, revealing a frequency of 0.4% in the women of reproductive age (20/4 792). Two previously known mutations:-77 T > C and -30 T > C and 3 novel δ-globin gene defects: -44G > A,CD87C > T, and CD134T > A were found. In the selected cases, we also found 85 cases confirmed with (51.2%,85/166) IDA and 39 cases (23.5%,39/166) with common α-thalassemia. Subjects with δ-thalassemia had statistically higher levels of Hb, MCV, and MCH compared with other two groups, whereas statistically lower levels of RDW were seen in δ-thalassemia group. What's more, statistically higher levels of SF were seen in δ-thalassemia group, compared with IDA groups. CONCLUSION: We reported the spectrum of δ-thalassemia mutations for the first time with the frequency of 0.4% among women of reproductive age in Fujian area and found that -77T > C mutation was the most common mutation, followed by -30T > C mutation. What's more, 3 novel δ-globin gene defects: -44G > A,CD87C > T and CD134T > A were found. A thorough analysis of the hematological, electrophoretic characterization, and the level of SF was needed to suspect and further investigate the existence of IDA, α-thalassemia, and δ-thalassemia.

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.