Prenatal chromosomal microarray analysis and karyotyping in fetuses with isolated choroid plexus cyst: A retrospective case-control study.

OBJECTIVES: To evaluate the the diagnostic yield of chromosomal microarray analysis (CMA) in fetuses with isolated CPC (iCPC). METHODS: A total of 315 fetuses with iCPC (iCPC group) and 364 fetuses without abnormal ultrasound findings (control group) were recruited between July 2014 to March 2018. RESULTS: The overall diagnostic yield of chromosomal abnormalities by CMA and karyotyping in iCPC group was up to 4.1 %, higher than 1.4 % in the control group, p < 0.05. The detection rate of pathogenic or likely pathogenic copy number variants (CNVs) with clinical significance by CMA in iCPC group (1.3 %) was higher than in control group (0 %), p < 0.05. According to the type of chromosome abnormalities, the missed diagnosis rate of non-invasive prenatal testing (NIPT) was 1.6 % in our study. CONCLUSIONS: The presence of iCPC on ultrasound examination suggests a potential indication for genetic counseling. Karyotyping and chromosomal microarray analysis may be considered for fetuses with iCPC. It is important to be aware of the limitations of non-invasive prenatal testing, as there is a possibility of residual risk.

Genetic Basis of Congenital Central Hypothyroidism in Children: Expanding the Mutational Spectrum of POU1F1 and ATP6V0A4.

Objective: Congenital central hypothyroidism (CCH) is a rare disorder poorly described in childhood and adolescence. The current knowledge on the genetic bases of CCH is scarce. The purpose of this study was to analyze the clinical characteristics and molecular genetic basis of CCH in children. Methods: We conducted a thorough evaluation of the clinical features in children diagnosed with CCH. Genomic DNA was extracted from peripheral blood of both children and their parents, and chromosomal microarray analysis and whole-exome sequencing were performed. Candidates for single nucleotide variants were validated using Sanger sequencing and were classified according to the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) guidelines. Results: Two cases with likely pathogenic variants were detected by whole-exome sequencing. Individual 1 carried a novel homozygous ATP6V0A4 c.1418C>T (p.Ser473Phe) variant and a novel heterozygous POU1F1 c.416G>A. (p.Arg139Gln) variant. Individual 2 had a novel homozygous POU1F1 c.212C>T (p.Ala71Val) variant. The chromosomal microarray detected the presence of a 24 Mb heterozygous deletion (LOH: loss of heterozygosity) in the p12.1p13.13 region of chromosome 2 in individual 3, and the copy number variant was unknown of clinical significance. Conclusion: Our study employed chromosomal microarray and whole-exome sequencing to investigate central hypothyroidism in seven children, leading to the detection of genetic anomalies in three individuals. The identification of novel variants has contributed to the expanded genetic spectrum of POU1F1 and ATP6V0A4 associated with pediatric central hypothyroidism.

[Comparison of performance of two prenatal diagnostic techniques for the detection of chromosomal mosaicisms in amniocytes].

OBJECTIVE: To assess the value of chromosomal karyotyping analysis and single nucleotide polymorphism-based microarray (SNP-array) for the detection of chromosomal mosaicisms in amniotic fluid samples. METHODS: Seventy four pregnant women with fetal mosaicisms detected by both methods were retrospectively analyzed. RESULTS: Among the 74 mosaicisms, 12 were pseudo and 62 were true mosaicisms, which included 1 Robertsonian translocation, 3 deletions, 4 supernumerary markers, 19 autosomal aneuploidy mosaicisms, 30 sex chromosome aneuploidy mosaicisms and 5 isometric chromosome mosaicisms. CONCLUSION: Chromosome karyotyping analysis and SNP-array have their own advantages and limitations for the diagnosis of mosaicisms. When the two methods have yielded inconsistent results, fluorescence in situ hybridization may be used for further verification.

Study on the correlation between the ultrasound phenotype and copy number variation of abnormal embryo in spontaneous abortion.

OBJECTIVE: This study aimed to explore the correlation between the ultrasound phenotype and copy number variation (CNV) of abnormal embryos in spontaneous abortion by investigating the abnormal chromosome copy number of embryos at different developmental stages in early spontaneous abortion. METHODS: A total of 539 patients who had early spontaneous abortion in our hospital between 2015 and 2019 were divided into seven groups according to the phenotype of abnormal embryonic development during pregnancy, and the embryonic tissues of the patients were subjected by single nucleotide polymorphism (SNP) microarray. RESULTS: Among 377 cases with abnormal CNV, 295 (78.25%) cases had chromosome trisomy, and 28 (7.43%) cases had a combination of more than two chromosomes. Triploidy, tetraploidy, chromosome microdeletion/duplication, uniparental disomy, and monosomy 45,X were found in 32 (8.48%), five (1.32%), 31 (8.22%), four (1.02%), and eight (2.12%) cases, respectively. Two (0.53%) cases had autosomal chromosome 21 monosomy. Normal karyotype had the highest proportion in the empty sac group; trisomy 16 accounted for the bulk of chromosomes in the normal yolk sac group, complex triploidy occupied the most part in the abnormal yolk sac group, and no remarkable difference in chromosomal abnormality proportion was found between the normal and abnormal yolk sac groups; the most frequent chromosomal anomaly in a group of germ without cardiac activity and germ<5 mm was trisomy 16; triploidy was the most common in the group with 5 mm ≤ germ ≤ 15 mm, whereas the main distribution of chromosome karyotype was normal, followed by trisomy 13 in a group with germ>15 mm. CONCLUSION: Abnormal embryos with different ultrasound phenotypes in early spontaneous abortion have various CNV types and characteristic distribution. Thus, ultrasound combined with SNP array can provide a basis for the etiological analysis of embryos in spontaneous abortion.

The application of expanded noninvasive prenatal screening for genome-wide chromosomal abnormalities and genetic counseling.

OBJECTIVE: To evaluate the clinical application of expanded noninvasive prenatal screening (eNIPS) for genome-wide large copy number variation (CNV), i.e. chromosomal deletion/duplication >5 Mb, and aneuploidy; also to provide practical information for counseling eNIPS positive cases. METHOD: We recruited 34,620 women with singleton pregnancy for genome-wide cell-free plasma DNA sequencing. Screening positive cases were verified by karyotyping and/or SNP array. RESULT: A total of 461 (1.33%) positive cases were identified through our cfDNA screening including 209 cases of common trisomies (0.60%), 124 cases of sex chromosomal abnormalities (SCA) (0.36%), 71 cases of other autosomal anueploidies (OAA) (0.21%), and 57 CNVs larger than 5 Mb (0.16%). The predictive positive values (PPV) were 70.06% in general for common trisomies with as high as 91.67% for Trisomy21 (T21), 40.22% in general for SCAs with as high as 100% for Jacob Syndrome (XYY). The PPV for OAAs was 5.45%, and T7/T8/T16/T22 were the most frequent OAAs (n = 15, 9, 9, 8, respectively). The PPV for CNVs larger than 5 Mb was 51.22% (n = 57) with the CNV mostly detected on Chr5/Chr4/Chr2/Chr7 (n = 10, 8, 5, 5, respectively). CONCLUSION: The expanded NIPS had shown promising PPVs for CNVs (large than 5 Mb), SCAs and common trisomies, yet this method required higher efficacy in screening for OAAs. The post-test genetic counseling for expanded NIPS should be tailored to the types of positive cases and also address the origin of abnormal signals (fetal vs. maternal).

Clinical application of whole-exome sequencing: A retrospective, single-center study.

The aim of the present study was to assess the practical diagnostic value of whole-exome sequencing (WES) in patients with different phenotypes and to explore possible strategies to increase the capability of WES in identifying disease-causing genes. A total of 1,360 patients (aged from 1 day to 42 years old) with manifestations of genetic diseases were genotyped using WES and statistical analysis was performed on the results obtained. Within this cohort, the overall positive rate of identification of a disease-causing gene alteration was 44.41%. The positive identification rate where trio-samples were used (from the proband and both parents) was higher than that where a single proband sample was used (50.00 vs. 43.71%), and 604 positive cases with 150 genetic syndromes, 510 genes and 718 mutations were detected. Missense mutations were the most common variations (n=335, 45.27%) and visual or auditory abnormalities (58.51%) had the highest rate of association with a genetic abnormality. The positive detection rate of WES was elevated with the increase in the number of clinical symptoms from 1 to 8. The present study indicated that WES may be used as a valuable tool in the clinic and the positive rate depends more on the professional experience of clinicians rather than on the analytical capabilities of the data analyst. At the same time, particular attention must be paid to certain possible factors (such as the age of the patients as well as possible exon deletions), which may affect the diagnostic rate while applying this process.

Performance of Cell-Free DNA Screening for Fetal Common Aneuploidies and Sex Chromosomal Abnormalities: A Prospective Study from a Less Developed Autonomous Region in Mainland China.

To evaluate the performance of noninvasive prenatal screening (NIPS) in the detection of common aneuploidies in a population-based study, a total of 86,262 single pregnancies referred for NIPS were prospectively recruited. Among 86,193 pregnancies with reportable results, follow-up was successfully conducted in 1160 fetuses reported with a high-risk result by NIPS and 82,511 cases (95.7%) with a low-risk result. The screen-positive rate (SPR) of common aneuploidies and sex chromosome abnormalities (SCAs) provided by NIPS were 0.7% (586/83,671) and 0.6% (505/83,671), respectively. The positive predictive values (PPVs) for Trisomy 21, Trisomy 18, Trisomy 13 and SCAs were calculated as 89.7%, 84.0%, 52.6% and 38.0%, respectively. In addition, less rare chromosomal abnormalities, including copy number variants (CNVs), were detected, compared with those reported by NIPS with higher read-depth. Among these rare abnormalities, only 23.2% (13/56) were confirmed by prenatal diagnosis. In total, four common trisomy cases were found to be false negative, resulting in a rate of 0.48/10,000 (4/83,671). In summary, this study conducted in an underdeveloped region with limited support for the new technology development and lack of cost-effective prenatal testing demonstrates the importance of implementing routine aneuploidy screening in the public sector for providing early detection and precise prognostic information.

Novel compound heterozygous frameshift variants in WDR81 associated with congenital hydrocephalus 3 with brain anomalies: First Chinese prenatal case confirms WDR81 involvement.

BACKGROUND: Congenital hydrocephalus-3 with brain anomalies (HYC3, MIM 617967) is a rare form of congenital hydrocephalus characterized by severe hydrocephalus and cerebellar abnormalities, the onset of the disease occurs in utero even resulting in fetal death. A very limited spectrum of WDR81 pathogenic variants had been reported in three unrelated families with HYC3. This study aims at presenting novel compound heterozygous frameshift variants in WDR81 in a Chinese fetus. METHODS: Whole-exome sequencing (WES) was performed for a fetus with multiple congenital anomalies including sever hydrocephalus, cleft lip and palate, hydrops fetalis, hepatomegaly, and cerebellar hypoplasia. Sanger sequencing was performed to confirm the origin of the variants subsequently. Variants classification was based on the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines. RESULTS: Two novel heterozygous variants c.146_147insG (p.Thr52fs) and c.673delC (p.Leu225fs) in WDR81 were identified. Sanger sequencing revealed that the c.146_147insG mutation was maternal origin and the c.673delC mutation was paternal origin. Both variants were pathogenic according to the ACMG/AMP guidelines. CONCLUSION: The present study expands the mutation spectrum of WDR81 and help further define the genotype-phenotype correlations of HYC3. WDR81-related HYC3 were highly clinical heterogeneity. We suggested that fetal hydrocephalus with extracerebral manifestations may be suggestive of WDR81 deficiency and WES is effective for achieving a conclusive diagnosis for disorder.

Targeted addition of mini-dystrophin into rDNA locus of Duchenne muscular dystrophy patient-derived iPSCs.

Duchenne muscular dystrophy (DMD), the most common lethal muscular disorder, affects 1 in 5000 male births. It is caused by mutations in the X-linked dystrophin gene (DMD), and there is no effective treatment currently. Gene addition is a promising strategy owing to its universality for patients with all gene mutations types. In this study, we describe a site-specific gene addition strategy in induced pluripotent stem cells (iPSCs) derived from a DMD patient with exon 50 deletion. By using transcription activator-like effector nickases (TALENickases), the mini-dystrophin cassette was precisely targeted at the ribosomal RNA gene (rDNA) locus via homologous recombination with high targeting efficiency. The targeted clone retained the main pluripotent properties and was differentiated into cardiomyocytes. Significantly, the dystrophin expression and membrane localization were restored in the genetic corrected iPSCs and their derived cardiomyocytes. More importantly, the enhanced spontaneous contraction was observed in modified cardiomyocytes. These results provide a proof of principle for an efficient targeted gene addition for DMD gene therapy and represents a significant step toward precisely therapeutic for DMD.

CNV profiles of Chinese pediatric patients with developmental disorders.

PURPOSE: To examine the overall genomic copy-number variant (CNV) landscape of Chinese pediatric patients with developmental disorders. METHODS: De-identified chromosomal microarray (CMA) data from 10,026 pediatric patients with developmental disorders were collected for re-evaluating the pathogenic CNV (pCNV) yields of different medical conditions and for comparing the frequency and phenotypic variability of genomic disorders between the Chinese and Western patient populations. RESULTS: The overall yield of pCNVs in the Chinese pediatric patient cohort was 21.37%, with variable yields for different disorders. Yields of pCNVs were positively associated with phenotypic complexity and intellectual disability/developmental delay (ID/DD) comorbidity for most disorders. The genomic burden and pCNV yield in neurodevelopmental disorders supported a female protective effect. However, the stratification analysis revealed that it was seen only in nonsyndromic ID/DD, not in nonsyndromic autism spectrum disorders or seizure. Furthermore, 15 known genomic disorders showed significantly different frequencies in Chinese and Western patient cohorts, and profiles of referred clinical features for 15 known genomic disorders were also significantly different in the two cohorts. CONCLUSION: We defined the pCNV yields and profiles of the Chinese pediatric patients with different medical conditions and uncovered differences in the frequency and phenotypic diversity of genomic disorders between Chinese and Western patients.

Two novel compound heterozygous variants of LTBP4 in a Chinese infant with cutis laxa type IC and a review of the related literature.

BACKGROUND: Autosomal recessive cutis laxa type IC (ARCL IC, MIM: #613177) results from a mutation in the LTBP4 gene (MIM: #604710) on chromosome 19q13. CASE PRESENTATION: A 28-day-old Chinese infant with generalized cutis laxa accompanied by impaired pulmonary, gastrointestinal, genitourinary, retinal hemorrhage, abnormality of coagulation and hyperbilirubinemia was admitted to our hospital. To find out the possible causes of these symptoms, whole-exome sequencing was performed on the infant. Two novel pathogenic frame-shift variants [c.605_606delGT (p.Ser204fs * 8) and c.1719delC (p.Arg574fs * 199)] of the LTBP4 gene associated with ARCL IC were found which was later verified by Sanger sequencing. The pathogenicity of mutations was subsequently assessed by several software programs and databases. In addition, an analytical review on the clinical phenotypes of the disease previously reported in literature was performed. CONCLUSIONS: This is the first report of a Chinese infant with ARCL IC in China due to novel pathogenic variations of LTBP4. Our study extends the cutis laxa type IC mutation spectrum as well as the phenotypes associated with the disease in different populations.

Clinical and Genetic Analysis of CHD7 Expands the Genotype and Phenotype of CHARGE Syndrome.

CHARGE syndrome is a life-threatening disease caused by mutations of chromodomain helicase DNA-binding protein 7 gene (CHD7). The disease is characterized by a pattern of congenital anomalies that involve multiple organs. In this study, five patients were diagnosed as CHARGE syndrome with CHD7 mutations by whole exome sequencing. Although the clinical phenotypes of probands are highly variable and typical symptoms such as coloboma and choanal atresia are not commonly manifested in this cohort, they all presented congenital heart defects. Of note, dyspnea is the most prominent symptom in all five neonatal patients, suggesting that dyspnea might be a phenotypic clue of CHARGE syndrome.

A novel pathogenic frameshift variant unmasked by a large de novo deletion at 13q21.33-q31.1 in a Chinese patient with neuronal ceroid lipofuscinosis type 5.

BACKGROUND: Neuronal ceroid lipofuscinosis type 5 (CLN5) is a rare form of neuronal ceroid lipofuscinoses (NCLs) which are a group of inherited neurodegenerative diseases characterized by progressive intellectual and motor deterioration, visual failure, seizures, behavioral changes and premature death. CLN5 was initially named Finnish variant late infantile NCL, it is now known to be present in other ethnic populations and with variable age of onset. Few CLN5 patients had been reported in Chinese population. CASE PRESENTATION: In this paper, we report the symptoms of a Chinese patient who suffer from developmental regression and grand mal epilepsy for several years. The DNA was extracted from peripheral blood of proband and both parents, and then whole exome sequencing was performed using genomic DNA. Both sequence variants and copy number variants (CNVs) were analyzed and classified according to guidelines. As the result, a novel frameshift mutation c.718_719delAT/p.Met240fs in CLN5 and a de novo large deletion at 13q21.33-q31.1 which unmasked the frameshift mutation were identified in the proband. Despite the large de novo deletion, which can be classified as a pathogenic copy number variant (CNV), the patient's clinical presentation is mostly consistent with that of CLN5, except for early developmental delay which is believed due to the large deletion. Both variants were detected simultaneously by exome sequencing. CONCLUSIONS: This is the first report of whole gene deletion in combination with a novel pathogenic sequence variant in a CLN5 patient. The two mutations detected with whole exome sequencing simultaneously proved the advantage of the sequencing technology for genetic diagnostics.

Novel compound heterozygous pathogenic variants in ASCC1 in a Chinese patient with spinal muscular atrophy with congenital bone fractures 2 : Evidence supporting a "Definitive" gene-disease relationship.

BACKGROUND: A very limited spectrum of ASCC1 pathogenic variants had been reported in six (mostly consanguineous) families with spinal muscular atrophy with congenital bone fractures 2 [OMIM #616867] since 2016. METHODS: A proband from a non-consanguineous Chinese family presented with neonatal severe hypotonia, respiratory distress, muscle weakness, and atrophy, as well as congenital bone fractures was performed by exome sequencing. RESULTS: A compound heterozygosity of a nonsense (c.932C>G,p.Ser311Ter) and an exon 5 deletion in ASCC1 segregating with phenotypes was detected, both variants are novel and pathogenic. Since ASCC1 is a relatively new disease gene, we performed the gene curation by ClinGen SOP. The existing evidence is sufficient to support a "Definitive" level of disease-gene relationship. CONCLUSION: This case report expended the mutation spectrum of ASCC1 and support the notion that this novel disease also occurs in outbreed populations and this is a rare disease but may still be underdiagnosed due to its perinatal lethal outcomes.

The first two Chinese Myhre syndrome patients with the recurrent SMAD4 pathogenic variants: Functional consequences and clinical diversity.

Myhre syndrome is a rare autosomal dominant multi-organ disorder characterized by growth retardation, skeletal anomalies, muscular hypertrophy, joint stiffness, facial dysmorphism, deafness, cardiovascular disease, and abnormal sexual development. Here we described the first two Chinese Myhre syndrome patients diagnosed by whole-exome sequencing. They both had de novo c.1498A > G (p.Ile500Val) variant in SMAD4 and presented with key characteristics of Myhre syndrome but also revealed uncommon features (polydactyly in the girl and precocious puberty in the boy). We performed functional analysis on four previously reported SMAD4 pathogenic variants in Myhre syndrome patients using dual-luciferase assay. Our results revealed that the pathogenic variants resulted in a variable degree of increased transcription activity of target genes that contain the minimal SMAD binding elements in their promoter regions. The boy responded to the recombinant human growth hormone treatment with improved height but also led to hyperinsulinemia and advanced bone age. Because of his precocious puberty, we subsequently combined the recombinant human growth hormone and gonadotrophin-releasing hormone agonist treatments, which resulted in overall improved height. We reviewed the sexual features of reported Myhre syndrome cases and discussed the possible mechanism of SMAD4 variants in Myhre syndrome that lead to the abnormal hypothalamic-pituitary-gonadal axis.

Prenatal diagnosis of cri-du-chat syndrome by SNP array: report of twelve cases and review of the literature.

BACKGROUND: Cri-du-chat syndrome (CdCS; OMIM#123450) is a classic contiguous gene syndrome caused by chromosome 5p terminal deletion (5p-), which characterized by a high-pitched cat-like cry, developmental delay, severe psychomotor, mental retardation, and dysmorphic features in infancy. Prenatal diagnosis of CdCS is difficult due to the non-specific ultrasound features. And reports using array analysis are rare. This study presented the first retrospective analysis of prenatal series of CdCS fetuses diagnosed by single nucleotide polymorphism (SNP) array in China. CASE PRESENTATION: A total of 35,233 pregnant women were enrolled from Jan 2014 to April 2019 in our center, there are twelve 5p- cases with abnormal sonographic signs revealed by SNP array, giving an incidence of 0.034% (12/35,233). Clinical information and molecular basis included: maternal demographics, indications for invasive testing, sonographic findings and SNP array results. Among all the 5p- cases revealed, nine cases were diagnosed by both karyotyping and SNP array, three cases were detected only by SNP array. Half of our cases (6/12) had an isolated 5p terminal deletion, which sizes ranged from 9.0 Mb to 30 Mb. The other half of cases (6/12) characterized by unbalanced translocation, with sex ratio 7:5 (female: male), when combine the clinical features observed from this study and available literature, the most frequent anomaly observed in prenatal ultrasound examination of CdCS was cerebral abnormalities, accounted for 44.4% (16/36) of the existing cases. Features that are less consistent included: choroid plexus cyst (13.8%, 5/36), single umbilical artery (13.3%, 4/30), ventricular septal defect (11.1%, 4/36), hydrops fetalis (8.3%, 3/36), ascites (8.3%, 3/36), increased NT/NF (8.3%, 3/36), absent/severely hypoplastic nasal bone (5.5%, 2/36), in order. CONCLUSION: Prenatal findings such as cerebral abnormalities, absent/hypoplastic nasal bone, hydrops fetalis, ascites or encephalocele may act as suggestive signs of CdCS or other microdeletion/duplication syndromes. Combining typical karyotyping with chromosomal microarray analysis (CMA) is a definitive method for a precise diagnosis of CdCS and provides more accurate results in order to offer genetic counseling to families which need to deal with cryptic aberrations.

Etiology and Outcome of non-immune Hydrops Fetalis in Southern China: report of 1004 cases.

Non-immune hydrops fetalis (NIHF) is a complex condition with a high mortality and morbidity rate. Here we report the etiology and outcome of 1004 fetuses with NIHF, in a large single Maternal and Children's hospital of Southern China, since the year of 2009 to 2016. Among these 1004 fetuses with NIHF, the etiology was identified prenatally in 722 of them (72%). The most common ones were hematologic diseases and chromosomal abnormalities. There were eight spontaneous abortions, 18 intrauterine fetal demise, 672 pregnancy terminations and 87 were lost to follow-up. 219 of the 1004 fetuses were live-born and the overall survival rate was 21.8% at this point. After birth 16 perinatal or early neonatal deaths were encountered and five lost to follow-up. Of the remaining 198 newborns, 153 thrived without apparent morbidity. The most significant factors associated with mortality were prematurity and low birthweight. In conclusion, we described the largest report of underlying causes and outcome of NIHF in Southern China. Etiologies were identified for 72% of 1004 fetuses with NIHF. And two poor prognostic factors for survival are preterm birth at less than 36.5 weeks and birthweight lower than 2575 g respectively.

Chromosomal microarray and whole exome sequencing identify genetic causes of congenital hypothyroidism with extra-thyroidal congenital malformations.

BACKGROUND: Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder. Although most patients present with isolated CH, some patients present with CH and extra-thyroidal congenital malformations (ECMs), for which less is known about the underlying genetics. The aim of this study was to investigate the genetic mechanisms in patients with CH and ECMs using chromosomal microarray (CMA) and whole exome sequencing (WES). METHODS: Peripheral venous blood samples were collected from 16 patients with CH and ECMs. Genomic DNA was extracted from peripheral blood leukocytes. CMA and WES were performed to detect copy number and single nucleotide variants. RESULTS: CMA identified clinically significant copy number variants in 7 patients consistent with their phenotypes. For 6 of them, the genotype and phenotype suggested a syndromic diagnosis, and the remaining patient carried a pathogenic microdeletion and microduplication including GLIS3. WES analysis identified 9 different variants in 7 additional patients. The variants included 2 known mutations (c.1096C>T (p.Arg366Trp) in KCNQ1 and c.848C>A (p.Pro283Gln) in NKX2-5) and 7 novel variants: one nonsense mutation (c.4330C>T (p.Arg1444*) in ASXL3), one frameshift mutation (c.1253_1259delACTCTGG (p.Asp418fs) in TG), three missense variants (c.1472C>T (p.Thr491Ile) in TG, c.4604A>G (p.Asp1535Gly) in TG, and c.2139G>T (p.Glu713Asp) in DUOX2, and two splice site variants (c.944-1G>C and c.3693 + 1G>T) in DUOX2. CONCLUSIONS: We report the first genetic study of CH patients with ECMs using CMA and WES. Overall, our detection rate for pathogenic and possibly pathogenic variants was 87.5% (14/16). We report 7 novel variants, expanding the mutational spectrum of TG, DUOX2, and ASXL3.

Novel pathogenic RECQL4 variants in Chinese patients with Rothmund-Thomson syndrome.

BACKGROUND: Rothmund-Thomson syndrome (RTS) is a rare autosomal recessive disorder mainly characterized by cutaneous poikiloderma, sparse hair, short stature and skeletal defects. Deleterious mutations in the RecQ-like DNA helicase type 4 (RECQL4) gene have been detected in approximately two-thirds of RTS cases. METHODS: Three Chinese patients from two unrelated families were enrolled for clinical evaluation. Targeted next-generation sequencing (NGS) using a custom panel consisting of 705 short-stature-related genes was performed for the probands. Variants detected by NGS were confirmed by Sanger sequencing and examined in family members. RESULTS: The probands presented with characteristic features of severe growth delay, poikiloderma mostly on the face, buttocks and extremities, sparse or absent hair, eyelashes, and eyebrows, forearm reduction defects, small hands with hypoplasia of the middle phalanx (little finger) in one of the probands, epicanthus, hypertelorism, and dental abnormalities. In addition, novel auricle features and other rare facial features, including narrow palpebral fissure, depressed nasal bridge, and small chin were exhibited. Four novel RECQL4 variants were identified, including three pathogenic frameshift variants, c.1724_1725delAC, p.His575fs*7; c.2421dupT, p.Asp808*; c.1770_1807del, p.Pro591fs*2, and one likely pathogenic missense variant, c.691G>A, p.Gly231Ser. CONCLUSION: Our study expands the mutational spectrum of RECQL4 gene and reveals novel phenotypes observed in Chinese RTS patients.

Newborn screening of glucose-6-phosphate dehydrogenase deficiency in Guangxi, China: determination of optimal cutoff value to identify heterozygous female neonates.

The aim of this study is to assess the disease incidence and mutation spectrum of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Guangxi, China, and to determine an optimal cutoff value to identify heterozygous female neonates. A total of 130, 635 neonates were screened from the year of 2013 to 2017. Neonates suspected for G6PD deficiency were further analyzed by quantitatively enzymatic assay and G6PD mutation analysis. The overall incidence of G6PD deficiency was 7.28%. A total of 14 G6PD mutations were identified, and different mutations lead to varying levels of G6PD enzymatic activities. The best cut-off value of G6PD activity in male subjects is 2.2 U/g Hb, same as conventional setting. In female population, however, the cut-off value is found to be 2.8 U/g Hb (sensitivity: 97.5%, specificity: 87.7%, AUC: 0.964) to best discriminate between normal and heterozygotes, and 1.6 U/g Hb (sensitivity: 82.2%, specificity: 85.9%, AUC: 0.871) between heterozygotes and deficient subjects. In conclusion, we have conducted a comprehensive newborn screening of G6PD deficiency in a large cohort of population from Guangxi, China, and first established a reliable cut-off value of G6PD activity to distinguish heterozygous females from either normal or deficient subjects.