Contribution of genetic variants to congenital heart defects in both singleton and twin fetuses: a Chinese cohort study.

BACKGROUND: The contribution of genetic variants to congenital heart defects (CHDs) has been investigated in many postnatal cohorts but described in few prenatal fetus cohorts. Overall, specific genetic variants especially copy number variants (CNVs) leading to CHDs are somewhat diverse among different prenatal cohort studies. In this study, a total of 1118 fetuses with confirmed CHDs were recruited from three units over a 5-year period, composing 961 of singleton pregnancies and 157 of twin pregnancies. We performed chromosomal microarray analysis on all cases to detect numerical chromosomal abnormalities (NCAs) and pathogenic/likely pathogenic CNVs (P/LP CNVs) and employed whole-exome sequencing for some cases without NCAs and P/LP CNVs to detect P/LP sequence variants (P/LP SVs). RESULTS: Overall, NCAs and P/LP CNVs were identified in 17.6% (197/1118) of cases, with NCA accounting for 9.1% (102/1118) and P/LP CNV for 8.5% (95/1118). Nonisolated CHDs showed a significantly higher frequency of NCA than isolated CHD (27.3% vs. 4.4%, p < 0.001), but there was no significant difference in the frequency of P/LP CNVs between isolated and nonisolated CHD (11.7% vs. 7.7%). A total of 109 P/LP CNVs were identified in 95 fetuses, consisting of 97 (89.0%) de novo, 6 (5.5%) parental inherited and 6 (5.5%) with unavailable parental information. The 16p11.2 proximal BP4-BP5 deletion was detected in 0.9% (10/1118) of all cases, second only to the most common 22q11.21 proximal A-D deletion (2.1%, 23/1118). Most of the 16p11.2 deletions (8/10) detected were de novo, and were enriched in CHD cases compared with a control cohort from a previous study. Additionally, SV was identified in 12.9% (8/62) of cases without NCA and P/LP CNV, most of which were de novo with autosomal dominant inheritance. CONCLUSIONS: Our cohort study provides a deep profile of the contribution of genetic variants to CHDs in both singleton and twin fetuses; NCA and P/LP CNV contribute to 9.1% and 8.5% of CHD in fetuses, respectively. We confirmed the 16p11.2 deletion as a CHD-associated hotspot CNV, second only to the 22q11.21 deletion in frequency. Most 16p11.2 deletions detected were de novo. Additionally, P/LP SV was identified in 12.9% (8/62) of fetuses without NCA or P/LP CNV.

Overall and individual associations between per- and polyfluoroalkyl substances and liver function indices and the metabolic mechanism.

Per- and polyfluoroalkyl substances (PFAS) can disrupt liver homeostasis. Studies have shown that a single exposure to PFAS may provoke abnormal liver function; however, few studies have investigated the overall effect of PFAS mixtures. We aimed to investigate associations between exposure to PFAS mixtures and liver function indices and explore the relevant mechanisms. This study included 278 adult males from Guangzhou, China. Serum metabolite profiles were analyzed using untargeted metabolomics. We applied weighted quantile sum (WQS) regression as well as Bayesian kernel machine regression (BKMR) to analyze the association of nine PFAS mixtures with 14 liver function indices. PFAS mixtures were positively associated with apolipoprotein B (APOB) and gamma-glutamyltransferase (GGT) and negatively associated with direct bilirubin (DBIL) and total bilirubin (TBIL) in both the WQS and BKMR analyses. In addition, Spearman's correlation test showed individual PFAS correlated with APOB, GGT, TBIL, and DBIL, while there's little correlation between individual PFAS and other liver function indices. In linear regression analysis, PFHxS, PFOS, PFHpS, PFNA, PFDA, and PFUdA were associated with APOB; PFOA, PFDA, PFOS, PFNA, and PFUdA were associated with GGT. Subsequently, a metabolome-wide association study and mediation analysis were combined to explore metabolites that mediate these associations. The mechanisms linking PFAS to APOB and GGT are mainly related with amino acid and glycerophospholipid metabolism. High-dimensional mediation analysis showed that glycerophospholipids are the main markers of the association between PFAS and APOB, and that (R)-dihydromaleimide, Ile Leu, (R)-(+)-2-pyrrolidone-5-carboxylic acid, and L-glutamate are the main markers of the association between PFAS and GGT. In summary, overall associations between PFAS and specific indices of liver function were found using two statistical methods; the metabolic pathways and markers identified here may serve to prompt more detailed study in animal-based systems, as well as a similar detailed analysis in other populations.

Prenatal evaluation of genetic variants in fetuses with small head circumference: A single-center retrospective study.

OBJECTIVES: To comprehensively evaluate the contributions of numerical chromosomal abnormality, copy number variant (CNV), and sequence variant (SV) to fetuses with small head circumference in a Chinese cohort using chromosome microarray analysis and whole exome sequencing. METHODS: A total of 157 fetuses with small heads defined as head circumference < - 2 standard deviation (SD) were recruited between October 2014 and March 2023. We used the ultrasonic measurement parameter Z-score to define small head as possible microcephaly (3 < Z ≤ -2), microcephaly (-5 < Z ≤ -3), or pathologic microcephaly (Z ≤ -5). Ultrasound findings and genetic results were analyzed. RESULTS: The overall diagnostic yield of chromosomal abnormalities by microarray analysis was 13 %. Whole exome sequencing revealed eight novel variants and two interesting candidate genes and provided a 25.4 % incremental yield compared with microarray analysis. Of the detected SVs, 56 % were de novo and the most common inheritance pattern was autosomal dominant inheritance presented in 11/16 fetuses. Compared with isolated small heads, non-isolated small heads had a significantly higher detection rate of chromosomal abnormalities (16 % vs. 3.0 %, P = 0.049) but not SVs (24 % vs. 5.5 %, P = 0.126). Subgroup analysis showed that intracranial anomalies had a similar high detection rate of SVs in fetuses with all small heads subgroups while no chromosomal abnormalities and causative SVs were found in fetuses with isolated possible microcephaly. CONCLUSIONS: Ultrasound findings of small fetal head circumference < 3 SD below the mean, especially those with intracranial structural abnormalities, indicate the need for genetic counseling. Genetic variants, mainly copy number variants and SV, may be responsible for the substantial proportion of small fetal head circumference, while most are de novo. Whole exome sequencing and microarray analysis are effective diagnostic approaches for this population.

Integrative profiling of extrachromosomal circular DNA in placenta and maternal plasma provides insights into the biology of fetal growth restriction and reveals potential biomarkers.

Introduction: Fetal growth restriction (FGR) is a placenta-mediated pregnancy complication that predisposes fetuses to perinatal complications. Maternal plasma cell-free DNA harbors DNA originating from placental trophoblasts, which is promising for the prenatal diagnosis and prediction of pregnancy complications. Extrachromosomal circular DNA (eccDNA) is emerging as an ideal biomarker and target for several diseases. Methods: We utilized eccDNA sequencing and bioinformatic pipeline to investigate the characteristics and associations of eccDNA in placenta and maternal plasma, the role of placental eccDNA in the pathogenesis of FGR, and potential plasma eccDNA biomarkers of FGR. Results: Using our bioinformatics pipelines, we identified multi-chromosomal-fragment and single-fragment eccDNA in placenta, but almost exclusively single-fragment eccDNA in maternal plasma. Relative to that in plasma, eccDNA in placenta was larger and substantially more abundant in exons, untranslated regions, promoters, repetitive elements [short interspersed nuclear elements (SINEs)/Alu, SINEs/mammalian-wide interspersed repeats, long terminal repeats/endogenous retrovirus-like elements, and single recognition particle RNA], and transcription factor binding motifs. Placental multi-chromosomal-fragment eccDNA was enriched in confident enhancer regions predicted to pertain to genes in apoptosis, energy, cell growth, and autophagy pathways. Placental eccDNA-associated genes whose abundance differed between the FGR and control groups were associated with immunity-related gene ontology (GO) terms. The combined analysis of plasma and placental eccDNA-associated genes in the FGR and control groups led to the identification of potential biomarkers that were assigned to the GO terms of the epigenetic regulation of gene expression and nutrient-related processes, respectively. Conclusion: Together, our results highlight links between placenta functions and multi-chromosomal-fragment and single-fragment eccDNA. The integrative analysis of placental and plasma eccDNA confirmed the potential of these molecules as disease-specific biomarkers of FGR.

Application of SNPs with low minor allele frequencies in missing person identification (MPI) through kinship analysis of DNA mixtures.

The need to identify a missing person (MP) through kinship analysis of DNA samples found at a crime scene has become increasingly prevalent. DNA samples from MPs can be severely degraded, contain little DNA and mixed with other contributors, which often makes it difficult to apply conventional methods in practice. This study developed a massively parallel sequencing-based panel that contains 1661 single-nucleotide polymorphisms (SNPs) with low minor allele frequencies (MAFs) (averaged at 0.0613) in the Chinese Han population, and the strategy for relationship inference from DNA mixtures comprising different numbers of contributors (NOCs) and of varying allele dropout probabilities. Based on the simulated dataset and genotyping results of 42 artificial DNA mixtures (NOC = 2-4), it was observed that the present SNP panel was sufficient for balanced mixtures when referenced to the closest relatives (parents/offspring and full siblings). When the mixture profiles suffered from dropout, incorrect assignments were markedly associated with relatedness, NOC and the dropout level. We, therefore, indicate that SNPs with low MAFs could be reliably interpreted for MP identification through the kinship analysis of complex DNA mixtures. Further studies should be extended to more possible scenarios to test the feasibility of this present approach.

Higher blood selenium level is associated with lower risk of hyperhomocysteinemia in the elderly.

BACKGROUND AND AIMS: Earlier studies have reported inconsistent association between selenium (Se) and homocysteine (Hcy) levels, while no evidence could be found from Chinese population. To fill this gap, we investigated the association between blood Se and hyperhomocysteinemia (HHcy) of rural elderly population in China. METHODS: A cross-sectional study on 1823 participants aged 65 and older from four Chinese rural counties was carried out in this study. Whole blood Se and serum Hcy concentrations were measured in fasting blood samples. Analysis of covariance and restricted cubic spline models were used to examine the association between Se and Hcy levels. Logistic regression models were used to evaluate the risk of prevalent HHcy among four Se quartile groups after adjusting for covariates. RESULTS: For this sample, the mean blood Se concentration was 156.34 (74.65) µg/L and the mean serum Hcy concentration was 17.25 (8.42) µmol/L. A significant non-linear relationship was found between blood Se and serum Hcy, the association was inverse when blood Se was less than 97.404 µg/L and greater than 156.919 µg/L. Participants in the top three blood Se quartile groups had significantly lower risk of prevalent HHcy compared with the lowest quartile group. When defined as Hcy> 10 µmol/L, the odds ratios and 95% confidence interval of HHcy were 0.600 (0.390, 0.924), 0.616 (0.398, 0.951) and 0.479 (0.314, 0.732) for Q2, Q3, and Q4 Se quartile groups compared with the Q1 group, respectively. When defined as Hcy≥ 15 µmol/L, the odds ratios and 95% confidence interval of HHcy were 0.833 (0.633, 1.098) and 0.827 (0.626, 1.092), 0.647 (0.489, 0.857) for Q2, Q3, and Q4 Se quartile groups compared with Q1 group. CONCLUSIONS: Our findings suggest that higher blood Se level could be a protective factor for HHcy in the elderly.

[A consensus on prenatal diagnosis and genetic counseling for chromosomal mosaicism].

With the extensive application of highly sensitive genetic techniques in the field of prenatal diagnosis, prenatal chromosomal mosaicisms including true fetal mosaicisms and confined placental mosaicisms are frequently identified in clinical settings, and the diagnostic criteria and principle of genetic counseling and clinical management for such cases may vary significantly among healthcare centers across the country. This not only has brought challenges to laboratory technician, genetic counselor and fetal medicine doctor, but can also cause confusion and anxiety of the pregnant woman and their family members. In this regard, we have formulated a consensus over the prenatal diagnosis and genetic counseling for chromosomal mosaicisms with the aim to promote more accurate and rational evaluation for fetal chromosomal mosaicisms in prenatal clinics.

Effect of exposures to mixtures of lead and various metals on hypertension, pre-hypertension, and blood pressure: A cross-sectional study from the China National Human Biomonitoring.

We aimed to explore the effects of mixtures of lead and various metals on blood pressure (BP) and the odds of pre-hypertension (systolic blood pressure (SBP) 120-139 mmHg, and/or diastolic blood pressure (DBP) 80-89 mmHg) and hypertension (SBP/DBP ≥140/90 mmHg) among Chinese adults in a cross-sectional study. This study included 11,037 adults aged 18 years or older from the 2017-2018 China National Human Biomonitoring. Average BP and 13 metals (lead, antimony, arsenic, cadmium, mercury, thallium, chromium, cobalt, molybdenum, manganese, nickel, selenium, and tin) in blood and urine were measured and lifestyle and demographic data were collected. Weighted multiple linear regressions were used to estimate associations of metals with BP in both single and multiple metal models. Weighted quantile sum (WQS) regression was performed to assess the relationship between metal mixture levels and BP. In the single metal model, after adjusting for potential confounding factors, the blood lead levels in the highest quartile were associated with the greater odds of both pre-hypertension (odds ratio (OR): 1.56, 95% CI: 1.22-1.99) and hypertension (OR:1.75, 95% CI: 1.28-2.40) when compared with the lowest quartile. We also found that blood arsenic levels were associated with increased odds of pre-hypertension (OR:1.31, 95% CI:1.00-1.74), while urinary molybdenum levels were associated with lower odds of hypertension (OR:0.68, 95% CI:0.50-0.93). No significant associations were found for the other 10 metals. WQS regression analysis showed that metal mixture levels in blood were significantly associated with higher SBP (ß = 1.56, P < 0.05) and DBP (ß = 1.56, P < 0.05), with the largest contributor being lead (49.9% and 66.8%, respectively). The finding suggests that exposure to mixtures of metals as measured in blood were positively associated with BP, and that lead exposure may play a critical role in hypertension development.

When a vesicular placenta meets a live fetus: case report of twin pregnancy with a partial hydatidiform mole.

BACKGROUND: Hydatidiform moles exhibit a distinctive gross appearance of multiple vesicles in the placenta. The advances in cytogenetic technologies have helped uncover novel entities of hydatidiform moles and enabled elaborate diagnoses. However, management of a vesicular placenta with a coexistent live fetus poses a bigger challenge beyond hydatidiform moles. CASE PRESENTATION: A 33-year-old woman was referred to our department for suspected hydatidiform mole coexistent with a live fetus at 24 weeks' gestation. The patient had conceived through double embryo transplantation, and first-trimester ultrasonography displayed a single sac. Mid-trimester imaging findings of normal placenta parenchyma admixed with multiple vesicles and a single amniotic cavity with a fetus led to suspicion of a singleton partial molar pregnancy. After confirmation of a normal diploid by amniocentesis and close surveillance, the patient delivered a healthy neonate. Preliminary microscopic examination of the placenta failed to clarify the diagnosis until fluorescence in situ hybridization showed a majority of XXY sex chromosomes. The patient developed suspected choriocarcinoma and achieved remission for 5 months after chemotherapy, but relapsed with suspected intermediate trophoblastic tumor. CONCLUSION: We report a rare case of twin pregnancy comprising a partial mole and a normal fetus that resembled a singleton partial molar pregnancy. Individualized care is important in conditions where a vesicular placenta coexists with a fetus. We strongly recommend ancillary examinations in addition to traditional morphologic assessment in such cases.

Elevated Hb A2 is Not Always Indicative of ß-Thalassemia.

Hb A2 levels are usually high in carriers of ß-thalassemia (ß-thal). These levels also provide a sensitive marker for the identification of hemoglobin (Hb) variants. In this study, we aimed to examine two patients from two Chinese families who showed elevated Hb A2 levels but did not show any signs of ß-thal. The HBB variants were analyzed using direct sequencing of HBB and in silico prediction analysis. Moreover, the family's genetic history was investigated. We examined two probands from different Chinese families with elevated Hb A2 levels who were not afflicted with ß-thal, although several nucleotide changes were found at codon 81 (CTC>CTA) (HBB: c.246C>A) in Family 1 and a compound heterozygosity for codon 40 (AGG>AAG) (HBB: c.122G>A) and IVS-II-478 (C>A) (HBB: c.316-373C>A) in Family 2. After investigating the genetic history of both families including the ß-thal aspect, we found that these mutations were not responsible for the elevated Hb A2 levels. It is rarely reported that high Hb A2 level is not indicative of ß-thal. In contrast, low or normal Hb A2 level is always found with ß-thal due to other molecular defects that mask their ß-thal genotype. Our results highlight the importance of considering the genetic factors related and unrelated to ß-thal to improve the accuracy of future genetic counseling.

Mosaic duplication of 8q24.1q24.3 detected by chromosomal microarray but not karyotyping in two unrelated fetuses with cardiac defects.

BACKGROUND: Discordance between traditional cytogenetic and molecular cytogenetic tests is rare but not uncommon. The explanation of discordance between two genetic methods is difficult but especially important for genetic counseling, particularly for prenatal genetic diagnosis. CASE PRESENTATION: Two unrelated fetuses were diagnosed with cardiac defects by prenatal ultrasound examination, and invasive cordocentesis was performed to obtain cord blood samples for prenatal genetic diagnosis. For both fetuses, chromosomal microarray analysis (CMA) detected a novel approximately 27-Mb mosaic duplication with a high copy number of approximately six to seven copies on chromosome 8q24.1q24.3 that was not identified by karyotyping. To exclude artificial errors and validate laboratory detection results, multiple procedures including copy number variation sequencing, fluorescence in situ hybridization, and short tandem repeat and single-nucleotide polymorphism genotype comparison were performed, confirming the discordant results between CMA and karyotyping. The potential causes of discordance between CMA and karyotyping using fetal blood lymphocytes are discussed; we suggest that extrachromosomal DNA or cell-free DNA fragmentation originating from certain tumor tissues with 8q24.1q24.3 duplication might deserve further investigation. CONCLUSIONS: This study may be helpful for prenatal evaluation and genetic counseling for subsequent patients with similar mosaic 8q24.1q24.3 duplications. Additionally, more cases and further research are needed to understand whether mosaic 8q24.1q24.3 duplication is associated with certain genetic disorders and to investigate the causes of discordance between molecular and morphological methods.

Case Report: Low-Level Maternal Mosaicism of a Novel CREBBP Variant Causes Recurrent Rubinstein-Taybi Syndrome in Two Siblings of a Chinese Family.

Familial Rubinstein-Taybi syndrome (RSTS) with recurrent RSTS siblings and apparently unaffected parents is rare; such cases might result from parental somatic and/or germline mosaicism. Parental low-level (<10%) germline mosaicism in the CREBBP-associated RSTS family has not been reported. Here, we present our studies of a Chinese family with two RSTS siblings and apparently unaffected parents. We detected the apparent de novo variant (DNV) c.3235C>T (p.Gln1079*) in CREBBP in the siblings via trio whole-exome sequencing. High-depth next-generation sequencing (NGS) for the parents revealed a low-level (<10%) mosaic variant in both the peripheral blood (3.64%) and buccal mucosa (1.94%) of the unaffected mother, indicating maternal somatic and germline mosaicism. Peripheral blood RNA-sequencing analysis for the patients and normal individuals indicated that the c.3235C>T (p.Gln1079*) non-sense variant did not trigger nonsense-mediated mRNA decay to reduce CREBBP mRNA levels. Transcriptome analysis revealed 151 downregulated mRNAs and 132 upregulated mRNAs between the patients and normal individuals. This study emphasizes that high-depth NGS using multiple specimens might be applied for a family with an affected sibling caused by an apparent CREBBP DNV to identify potential low-level parental mosaicism and provide an assessment of recurrence risk.

Cohort profile: China National Human Biomonitoring (CNHBM)-A nationally representative, prospective cohort in Chinese population.

OBJECTIVE: Globally, developed countries such as the United States, Canada, Germany, Korea, have carried out long-term and systematic biomonitoring programs for environmental chemicals in their populations. The China National Human Biomonitoring (CNHBM) was to document the extent of human exposure to a wide array of environmental chemicals, to understand exposure profiles, magnitude and ongoing trends in exposure in the general Chinese population, and to establish a national biorepository. METHODS: CNHBM adopted three-stage sampling method to obtain a nationally representative sample of the population. A total of 21,888 participants who were permanent residents in 31 provinces were designed to interviewed in this national biomonitoring (152 monitoring sites × 3 survey units × 2 sexes × 6 age groups × 4 persons = 21,888 persons) in 2017-2018. Unlike the US National Health and Nutrition Examination Survey, the CNHBM will follow the same participants in subsequent cycles allowing for dynamic, longitudinal data sets for epidemiologic follow-up. Each survey cycle of CNHBM will last 2 years and each subsequent cycle will occur 3 years after the prior cycle's completion. RESULTS: In 2017-2018, the CNHBM created a large cohort of Chinese citizens that included districts/counties questionnaire, community questionnaire collecting information on villages/communities, individual questionnaire, household questionnaire, comprehensive medical examination, and collection of blood and urine samples for measurement of clinical and exposure biomarkers. A total of 21,746 participants were finally included in CNHBM, accounting for 99.4% of the designed sample size; and 152 PSUs questionnaires, 454 community questionnaires, 21,619 family questionnaires, 21,712 cases of medical examinations, 21,700 individual questionnaires, 21,701 blood samples and 21,704 urine samples were collected, respectively. Planned analyses of blood and urine samples were to measure both inorganic and organic chemicals, including 13 heavy metals and metalloids, 18 poly- and per-fluorinated alkyl substances, 12 phthalate metabolites, 9 polycyclic aromatic hydrocarbons metabolites, 4 environmental alkylated phenols, and 2 benzene metabolites. CONCLUSIONS: CNHBM established the first nationally representative, prospective cohort in the Chinese population to understand the baseline and trend of internal exposure of environmental chemicals in general population, and to understand environmental toxicity.

Higher blood cadmium level is associated with greater cognitive decline in rural Chinese adults aged 65 or older.

Cadmium (Cd) exposure has been reported to have neurotoxic effects in animal studies and associated with increased Alzheimer's Disease mortality and lower cognitive function in cross-sectional and case-control studies. However, no results from longitudinal studies on Cd and cognitive decline are available. In this prospective cohort study, we recruited 1867 participants aged 65 years or older from rural areas in China, blood Cd and cognitive function were measured at baseline (2010-2012), and 1554 participants completed cognitive function tests during a 3-year follow-up (2013-2015). Cognitive function was evaluated using nine standardized cognitive tests: The Community Screening Instrument for Dementia, the CERAD Word List Learning, Word list recall, IU Story Recall, Animal Fluency Test, Boston Naming Test, Stick Design, Delayed Stick Design and the IU Token Test. Analysis of covariance models and logistic regression models were used to determine the association between Cd and standardized cognitive decline adjusting for covariates. The median blood Cd concentration of this study population was 2.12 µg/L, and the interquartile range was 1.42-4.64 µg/L. Significant association of higher Cd levels with lower cognitive scores were observed in five individual cognitive tests (Delayed Stick Design Test, Boston Naming Test, CERAD Word List Learning Test, Word List Recall Test and IU Story Recall Test) and the composite cognitive score adjusting for multi-covariates at baseline. Higher Cd levels were significantly associated with greater 3-year cognitive decline in Delayed Stick Design Test, Boston Naming Test, IU Token Test, Word List Recall Test and Composite cognitive score. For these cognitive tests, participants in the top two Cd quartile groups had significantly greater decline than those in the lowest Cd quartile group, while the two lowest Cd quartile groups were not significantly different. Our findings suggest that higher Cd exposure is associated with greater cognitive decline in older Chinese adults.

Evaluation of a Microhaplotype-Based Noninvasive Prenatal Test in Twin Gestations: Determination of Paternity, Zygosity, and Fetal Fraction.

As a novel type of genetic marker, the microhaplotype has shown promising potential in forensic research. In the present study, we analyzed maternal plasma cell-free DNA (cfDNA) samples from twin pregnancies to validate microhaplotype-based noninvasive prenatal testing (NIPT) for paternity, zygosity, and fetal fraction (FF). Paternity was determined with the combined use of the relMix package, zygosity was evaluated by examining the presence of informative loci with two fetal genome complements, and FF was assessed through fetal allele ratios. Paternity was determined in 19 twin cases, among which 13 cases were considered dizygotic (DZ) twins based on the presence of 3~10 informative loci and the remaining 6 cases were considered monozygotic (MZ) twins because no informative locus was observed. With the fetal genomic genotypes as a reference, the accuracy of paternity and zygosity determination were confirmed by standard short tandem repeat (STR) analysis. Moreover, the lower FF, higher FF, and combined FF in each DZ plasma sample were closely related to the estimated value. This present preliminary study proposes that microhaplotype-based NIPT is applicable for paternity, zygosity, and FF determination in twin pregnancies, which are expected to be advantageous for both forensic and clinical settings.

A novel ß-thalassemia variant at HBB:c.14delC (Codon 4, -C) identified via next-generation sequencing.

OBJECTIVES: ß-Thalassemia (ß-thal) is a genetic disease of the blood caused by mutations in the ß-globin gene. Conventional methods for detecting thalassemia variants often miss rare and novel variants. Identifying the rare and novel ß-thal variants, especially in the high prevalence regions, would enable better disease prevention. METHODS: A Chinese family who had joined the Thalassemia Prevention Program was recruited in this study. The ß-thal carrier screening was performed using next-generation sequencing (NGS), and the results were validated through direct DNA sequencing. Hematological parameters were analyzed, and hemoglobin electrophoresis was performed. Additionally, the presence of thalassemia-associated deletions was determined using gap-polymerase chain reaction. RESULTS: A novel frameshift variant of ß-thal, HBB:c.14delC(Codon 4, -C), was identified in a 31-year-old Chinese man. Subsequent genetic investigation showed that his mother also carried this novel variant. Hematological analysis and clinical evaluation suggested that this variant was present in the heterozygous state and might belong to a severe phenotype of ß-thal. CONCLUSIONS: We identified a novel frameshift variant of ß-thal. NGS has the potential for identifying rare and novel thalassemia variants and broadening the spectrum of thalassemia screening and thus may contribute to effective prevention of thalassemia.

[A consensus recommendation for the interpretation and reporting of exome sequencing in prenatal genetic diagnosis].

With the rapid development and adaptation of high-throughput sequencing in clinical settings, application of exome sequencing (ES) has been gradually expanded from pediatric to prenatal diagnosis in recent years. There is an urgent need to establish criteria for clinical grade ES in order to facilitate such a complex testing. The standardization of pre- and post-test consultation, quality control for sample processing process and validation of bioinformatics data analysis, and more importantly data interpretation and reporting, as well as appropriate reporting scope, is of great importance for health care stakeholders. To achieve this, a committee composed of a wide range of healthcare professionals has proposed an ES standard for prenatal diagnosis. This has provided expert opinion on the genetic counseling and reporting standards of prenatal ES for the purpose of applying ES technology in prenatal setting.

[Clinical and genetic analysis of a patient with 17-hydroxylase/17,20-lyase deficiency].

OBJECTIVE: To explore the clinical and genetic characteristics of a patient with 17-hydroxylase/17,20-lyase deficiency. METHODS: The patient was infertile without contraception. Laboratory examination showed her chromosomal karyotype to be 46, XX. DNA sequencing was performed to detect variants of CYP17A1 gene in the patient and her family members. RESULTS: Sanger sequencing revealed that the patient has carried homozygous variant c.1486C>T in the exon 8 of the CYP17A1 gene, which resulted in substitution of arginine by cysteine (p.Arg496Cys). Her family members were all heterozygotes for the same variant. CONCLUSION: Homozygous variant of the CYP17A1 gene c.1486C>T probably underlay the 17-hydroxylase deficiency in this patient. Above finding has enabled accurate genetic counseling and prenatal diagnosis for her family.

A child with a novel DDX3X variant mimicking cerebral palsy: a case report.

BACKGROUND: Cerebral palsy (CP) is a non-progressive disorder of movement and posture due to a static insult to the brain. In CP, the depth of investigation is guided by the patients' medical history and their clinical examination. Magnetic resonance imaging (MRI) has a high yield and is widely used for investigation in CP. CASE PRESENTATION: In this paper, we report a novel DDX3X variant in a girl afflicted with the X-linked mental retardation-102 (MRX102). The girl had been misdiagnosed with CP in her early life based on a comprehensive clinical evaluation and associated clinical features, such as developmental delay, reduced activities of the arms and legs, and abnormal brain MRI. Subsequently, whole-exome sequencing was applied to better distinguish between CP and actual MRX102 with similar characteristics. CONCLUSIONS: We report on a de novo heterozygous DDX3X variant mimicking cerebral palsy and suggest a thorough and conscientious review during diagnosis of CP.