Three-way contact analysis characterizes the higher order organization of the Tcra locus.

The generation of highly diverse antigen receptors in T and B lymphocytes relies on V(D)J recombination. The enhancer Eα has been implicated in regulating the accessibility of Vα and Jα genes through long-range interactions during rearrangements of the T-cell antigen receptor gene Tcra. However, direct evidence for Eα physically mediating the interaction of Vα and Jα genes is still lacking. In this study, we utilized the 3C-HTGTS assay, a chromatin interaction technique based on 3C, to analyze the higher order chromatin structure of the Tcra locus. Our analysis revealed the presence of sufficient information in the 3C-HTGTS data to detect multiway contacts. Three-way contact analysis of the Tcra locus demonstrated the co-occurrence of the proximal Jα genes, Vα genes and Eα in CD4+CD8+ double-positive thymocytes. Notably, the INT2-TEAp loop emerged as a prominent structure likely to be responsible for bringing the proximal Jα genes and the Vα genes into proximity. Moreover, the enhancer Eα utilizes this loop to establish physical proximity with the proximal Vα gene region. This study provides insights into the higher order chromatin structure of the Tcra locus, shedding light on the spatial organization of chromatin and its impact on V(D)J recombination.

Correlation between maternal serum biomarkers and the risk of fetal chromosome copy number variants: a single-center retrospective study.

OBJECTIVE: To explore the association between the concentration of maternal serum biomarkers and the risk of fetal carrying chromosome copy number variants (CNVs). METHODS: Pregnant women identified as high risk in the second-trimester serological triple screening and underwent traditional amniotic fluid karyotype analysis, along with comparative genomic hybridization array (aCGH)/copy number variation sequencing (CNV-seq), were included in the study. We divided the concentration of serum biomarkers, free beta-human chorionic gonadotropin (fß-hCG), alpha fetoprotein (AFP) and unconjugated estriol (uE3), into three levels: abnormally low, normal and abnormally high. The prevalence of abnormally low, normal and abnormally high serum fß-hCG, AFP and uE3 levels in pregnant women with aberrant aCGH/CNV-seq results and normal controls was calculated. RESULTS: Among the 2877 cases with high risk in the second-trimester serological triple screening, there were 98 chromosome abnormalities revealed by karyotype analysis, while 209 abnormalities were detected by aCGH/CNVseq (P＜0.001) . The carrying rate of aberrant CNVs increased significantly when the maternal serum uE3 level was less than 0.4 multiple of median (MoM) of corresponding gestational weeks compared to normal controls, while the carrying rate of aberrant CNVs decreased significantly when the maternal serum fß-hCG level was greater than 2.5 MoM compared to normal controls. No significant difference was found in the AFP group. CONCLUSION: Low serum uE3 level (<0.4 MoM) was associated with an increased risk of aberrant CNVs.

[Application of whole exome sequencing for the inferential analysis of recessive genetic disease carrier status for couples with a child died of Primary immunodeficiency].

OBJECTIVE: To explore the value of whole exome sequencing for the inferential analysis of recessive genetic disease carrier status for couples with a child died of Primary immunodeficiency (PID). METHODS: Clinical data was collected from four couples with a childbearing history of PID who had sought genetic counseling and undergone genetic testing at Henan Provincial People's Hospital from February 2017 to December 2021. Whole exome sequencing (WES) was performed on both partners of each couple, and candidate variants were validated by Sanger sequencing and fluorescent quantitative PCR. Prenatal diagnosis was conducted on fetuses of these couples after confirming the variants. RESULTS: A total of six variants were detected in four genes including IL2RG, BTK, CYBB, and DUOX2. Among these, the c.1265G>A and c.3329G>A variants of the DUOX2 gene and the c.676C>T variant of the IL2RG gene were previously known as pathogenic variants. On the other hand, the Exon5_8del variant of the IL2RG gene, the c.184_185delAC variant of the BTK gene, and the c.472A>T variant of the CYBB gene were unreported previously. Based on the guidelines from the American College of Medical Genetics and Genomics, the IL2RG: Exon5_8del, BTK: c.184_185delAC and CYBB: c.472A>T variants were classified as likely pathogenic (PVS1+PM2_Supporting+PP4).Prenatal diagnosis was conducted for three couples during their subsequent pregnancies, and the results revealed that the fetuses had the wild-type genotypes at the c.184_185 position of the BTK gene, the c.472 position of the CYBB gene, and the c.676 position of the IL2RG gene. Follow-up examinations one year after birth has found no abnormality in the infants. CONCLUSION: WES is an important tool to infer and analyze the carrier status for couples who had given births to children died of PID and improve the positive detection rate.

[Clinical features and genetic analysis of 17 Chinese pedigrees affected with X-linked intellectual disability].

OBJECTIVE: To analyze the clinical features and genetic etiology of 17 Chinese pedigrees affected with X-linked intellectual disability (XLID). METHODS: Seventeen pedigrees affected with unexplained intellectual disability which had presented at Henan Provincial People's Hospital from May 2021 to May 2023 were selected as the study subjects. Clinical data of the probands and their pedigree members were collected. Trio-whole exome sequencing (Trio-WES), Sanger sequencing and X chromosome inactivation (XCI) analysis were carried out. Pathogenicity of candidate variants was predicted based on the guidelines from the American College of Medical Genetics and Genomics and co-segregation analysis. RESULTS: The 17 probands, including 9 males and 8 females with an age ranging from 0.6 to 8 years old, had all shown mental retardation and developmental delay. Fourteen variants were detected by genetic testing, which included 4 pathogenic variants (MECP2: c.502C>T, MECP2: c.916C>T/c.806delG, IQSEC2: c.1417G>T), 4 likely pathogenic variants (MECP2: c.1157_1197del/c.925C>T, KDM5C: c.2128A>T, SLC6A8: c.1631C>T) and 6 variants of uncertain significance (KLHL15: c.26G>C, PAK3: c.970A>G/c.1520G>A, GRIA3: c.2153C>G, TAF1: c.2233T>G, HUWE1: c.10301T>A). The PAK3: c.970A>G, GRIA3: c.2153C>G and TAF1: c.2233T>G variants were considered as the genetic etiology for pedigrees 12, 14 and 15 by co-segregation analysis, respectively. The proband of pedigree 13 was found to have non-random XCI (81:19). Therefore, the PAK3: c.1520G>A variant may underlie its pathogenesis. CONCLUSION: Trio-WES has attained genetic diagnosis for the 17 XLID pedigrees. Sanger sequencing and XCI assay can provide auxiliary tests for the diagnosis of XLID.

Integration of ATAC-seq and RNA-seq identifies MX1-mediated AP-1 transcriptional regulation as a therapeutic target for Down syndrome.

BACKGROUND: Growing evidence has suggested that Type I Interferon (I-IFN) plays a potential role in the pathogenesis of Down Syndrome (DS). This work investigates the underlying function of MX1, an effector gene of I-IFN, in DS-associated transcriptional regulation and phenotypic modulation. METHODS: We performed assay for transposase-accessible chromatin with high-throughout sequencing (ATAC-seq) to explore the difference of chromatin accessibility between DS derived amniocytes (DSACs) and controls. We then combined the annotated differentially expressed genes (DEGs) and enriched transcriptional factors (TFs) targeting the promoter region from ATAC-seq results with the DEGs in RNA-seq, to identify key genes and pathways involved in alterations of biological processes and pathways in DS. RESULTS: Binding motif analysis showed a significant increase in chromatin accessibility of genes related to neural cell function, among others, in DSACs, which is primarily regulated by members of the activator protein-1 (AP-1) transcriptional factor family. Further studies indicated that MX Dynamin Like GTPase 1 (MX1), defined as one of the key effector genes of I-IFN, is a critical upstream regulator. Its overexpression induced expression of AP-1 TFs and mediated inflammatory response, thus leading to decreased cellular viability of DS cells. Moreover, treatment with specific AP-1 inhibitor T-5224 improved DS-associated phenotypes in DSACs. CONCLUSIONS: This study demonstrates that MX1-mediated AP-1 activation is partially responsible for cellular dysfunction of DS. T-5224 effectively ameliorated DS-associated phenotypes in DSACs, suggesting it as a potential treatment option for DS patients.

[Expert consensus on the genetic diagnosis for Dystrophinopathies].

Dystrophinopathies, including Duchenne muscular dystrophy, Becker muscular dystrophy and dilated cardiomyopathy, are X-linked recessive genetic disorders due to variants of the dystrophin gene, which can seriously affect quality of life and health. Genetic diagnosis plays a crucial role in their diagnosis, treatment, and prevention. How to rationally select and standardize the use of various genetic techniques is a skill that clinicians must acquire. By compiling expertise of experts from the relevant areas and guidelines published home and abroad, this consensus has provided a guidance from the perspective of genetic diagnosis for the selection of genetic techniques, testing strategies, and detection process for dystrophinopathies.

[Clinical and genetic analysis of two children with intellectual developmental disorder and microcephaly with pontine and cerebellar hypoplasia].

OBJECTIVE: To explore the clinical features and genetic etiology of two children with intellectual developmental disorder and microcephaly with pontine and cerebellar hypoplasia (MICPCH). METHODS: Two children with MICPCH who were presented at the Henan Provincial People's Hospital between April 2019 and December 2021 were selected as the study subjects. Clinical data of the two children were collected, along with peripheral venous blood samples of them and their parents, and amniotic fluid sample of the mother of child 1. Whole exome sequencing (WES), array-comparative genomic hybridization (aCGH) and real-time quantitative PCR (qPCR) were carried out for the children, their parents and the fetus. The pathogenicity of candidate variants were evaluated. RESULTS: Child 1 was a 6-year-old girl featuring motor and language delay, whilst child 2 was a 4.5-year-old girl mainly featuring microcephaly and mental retardation. WES revealed that child 2 has harbored a 158.7 kb duplication in Xp11.4 (chrX: 41446160_41604854), which has encompassed exons 4~14 of the CASK gene. The same duplication was not found in either of her parents. aCGH revealed that child 1 has harbored a 29 kb deletion at Xp11.4 (chrX: 41637892_41666665), which encompassed exon 3 of the CASK gene. The same deletion was not found in either of her parents and the fetus. The above results were confirmed by qPCR assay. Above deletion and duplication were not found in the ExAC, 1000 Genomes and gnomAD databases. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were rated as likely pathogenic (PS2+PM2_Supporting). CONCLUSION: The deletion of exon 3 and duplication of exons 4~14 of the CASK gene probably underlay the pathogenesis of MICPCH in these two children, respectively.

[Analysis of a fetus with unbalanced translocation derived from a balanced t(6;14) maternal translocation].

OBJECTIVE: To explore the genetic characteristics of a fetus with a high risk by maternal serum screening during the second trimester. METHODS: Genetic counseling was provided to the pregnant woman on March 22, 2020 at Henan Provincial People's Hospital. G-banded chromosomal karyotyping and array comparative genomic hybridization (aCGH) were carried out on the amniotic fluid sample and peripheral blood samples from the couple. RESULTS: The fetus and the pregnant woman were respectively found to have a 46,XX,der(6)t(6;14)(q27;q31.2) and 46,XX,t(6;14)(q27;q31.2) karyotype, whilst the husband was found to have a normal karyotype. aCGH analysis has identified a 6.64 Mb deletion at 6q26q27 and a 19.98 Mb duplication at 14q31.3q32.33 in the fetus, both of which were predicted to be pathogenic copy number variations. No copy number variation was found in the couple. CONCLUSION: The unbalanced chromosome abnormalities in the fetus have probably derived from the balanced translocation carried by the pregnant woman. aCGH can help to determine the types of fetal chromosome abnormalities and site of chromosomal breakage, which may facilitate the prediction of fetal outcome and choice for subsequent pregnancies.

[Clinical features and genetic analysis of two Chinese pedigrees affected with Joubert syndrome].

OBJECTIVE: To explore the clinical characteristics and genetic basis of two Chinese pedigrees affected with Joubert syndrome. METHODS: Clinical data of the two pedigrees was collected. Genomic DNA was extracted from peripheral blood samples and subjected to high-throughput sequencing. Candidate variants were verified by Sanger sequencing. Prenatal diagnosis was carried out for a high-risk fetus from pedigree 2. RESULTS: The proband of pedigree 1 was a fetus at 23+5 weeks gestation, for which both ultrasound and MRI showed "cerebellar vermis malformation" and "molar tooth sign". No apparent abnormality was noted in the fetus after elected abortion. The fetus was found to harbor c.812+3G>T and c.1828G>C compound heterozygous variants of the INPP5E gene, which have been associated with Joubert syndrome type 1. The proband from pedigree 2 had growth retardation, mental deficiency, peculiar facial features, low muscle tone and postaxial polydactyly of right foot. MRI also revealed "cerebellar dysplasia" and "molar tooth sign". The proband was found to harbor c.485C>G and c.1878+1G>A compound heterozygous variants of the ARMC9 gene, which have been associated with Joubert syndrome type 30. Prenatal diagnosis found that the fetus only carried the c.485C>G variant. A healthy infant was born, and no anomalies was found during the follow-up. CONCLUSION: The compound heterozygous variants of the INPP5E and ARMC9 genes probably underlay the disease in the two pedigrees. Above finding has expanded the spectrum of pathogenic variants underlying Joubert syndrome and provided a basis for genetic counseling and prenatal diagnosis.

[Genetic analysis of two children with developmental delay and intellectual disability].

OBJECTIVE: To explore the genetic etiology of two patients with developmental delay and intellectual disability. METHODS: Two children who were respectively admitted to Henan Provincial People's Hospital on August 29, 2021 and August 5, 2019 were selected as the study subjects. Clinical data were collected, and array comparative genomic hybridization (aCGH) was carried out on the children and their parents for the detection of chromosomal microduplication/microdeletions. RESULTS: Patient 1 was a 2-year-and-10-month female and patient 2 was a 3-year-old female. Both children had featured developmental delay, intellectual disability, and abnormal findings on cranial MRI. aCGH revealed that patient 1 has harbored arr[hg19] 6q14.2q15(84621837_90815662)×1, a 6.19 Mb deletion at 6q14.2q15, which encompassed ZNF292, the pathogenic gene for Autosomal dominant intellectual developmental disorder 64. Patient 2 has harbored arr[hg19] 22q13.31q13.33(46294326_51178264)×1, a 4.88 Mb deletion at 22q13.31q13.33 encompassing the SHANK3 gene, haploinsufficiency of which can lead to Phelan-McDermid syndrome. Both deletions were classified as pathogenic CNVs based on the guidelines of American College of Medical Genetics and Genomics (ACMG) and were not found in their parents. CONCLUSION: The 6q14.2q15 deletion and 22q13-31q13.33 deletion probably underlay the developmental delay and intellectual disability in the two children, respectively. Haploinsufficiency of the ZNF292 gene may account for the key clinical features of the 6q14.2q15 deletion.

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

OBJECTIVE: To explore the genetic basis for fetus with bilateral lateral ventriculomegaly. METHODS: Fetus umbilical cord blood and peripheral blood samples of its parents were collected. The fetus was subjected to chromosomal karyotyping, whilst the fetus and its parents were subjected to array comparative genomic hybridization (aCGH). The candidate copy number variation (CNV) were verified by qPCR, Application goldeneye DNA identification system was used to confirm the parental relationship. RESULTS: The fetus was found to have a normal karyotype. aCGH analysis indicated that it has carried a 1.16 Mb deletion at 17p13.3, which partially overlapped with the critical region of Miller-Dieker syndrome (MDS), in addition with a 1.33 Mb deletion at 17p12 region, which is associated with hereditary stress-susceptible peripheral neuropathy (HNPP). Its mother was also found to harbor the 1.33 Mb deletion at 17p12. qPCR analysis confirmed that the expression levels of genes from the 17p13.3 and 17p12 regions were about the half of that in the normal control, as well as the maternal peripheral blood sample. Parental relationship was confirmed between the fetus and its parents. Following genetic counseling, the parents has chosen to continue with the pregnancy. CONCLUSION: The fetus was diagnosed with Miller-Dieker syndrome due to the de novo deletion at 17p13.3. Ventriculomegaly may be an important indicator for prenatal ultrasonography in fetuses with MDS.

Genome sequencing demonstrates high diagnostic yield in children with undiagnosed global developmental delay/intellectual disability: A prospective study.

Genome sequencing (GS) has been used in the diagnosis of global developmental delay (GDD)/intellectual disability (ID). However, the performance of GS in patients with inconclusive results from chromosomal microarray analysis (CMA) and exome sequencing (ES) is unknown. We recruited 100 pediatric GDD/ID patients from multiple sites in China from February 2018 to August 2020 for GS. Patients have received at least one genomic diagnostic test before enrollment. Reanalysis of their CMA/ES data was performed. The yield of GS was calculated and explanations for missed diagnoses by CMA/ES were investigated. Clinical utility was assessed by interviewing the parents by phone. The overall diagnostic yield of GS was 21%. Seven cases could have been solved with reanalysis of ES data. Thirteen families were missed by previous CMA/ES due to improper methodology. Two remained unsolved after ES reanalysis due to complex variants missed by ES, and a CNV in untranslated regions. Follow-up of the diagnosed families revealed that nine families experienced changes in clinical management, including identification of targeted treatments, cessation of unnecessary treatment, and considerations for family planning. GS demonstrated high diagnostic yield and clinical utility in this undiagnosed GDD/ID cohort, detecting a wide range of variant types of different sizes in a single workflow.

A Novel Variant of the KIF11 Gene, c.2922G>T, Is Associated with Microcephaly by Affecting RNA Splicing.

Microcephaly with or without chorioretinopathy, lymphedema, or mental retardation (MCLMR) is an inherited disorder characterized by severe microcephaly and abnormal facial features. Kinesin family member 11 (KIF11) mutations have been reported closely related to microcephaly in different cases, while the pathogenicity was still unclear. Here, we report a de novo heterozygous mutation in exon 20 of the KIF11 (c.2922G>T; p.Pro974=) from a microcephaly patient through whole-exome sequencing. Further studies identified that this variant affected the normal splicing of KIF11 pre-mRNA, thus leading to the c.2815_2922 deletion of exon 20 through PBMC-derived pre-mRNA splicing assay and minigene experiment. Moreover, c.2815_2922 deletion would produce a shortened KIF11 protein, which may competitively bind to the normal KIF11 protein, suggesting a dominant negative effect mechanism in c.2922G>T mutation-induced MCLMR.

Different effects of maternal homocysteine concentration, MTHFR and MTRR genetic polymorphisms on the occurrence of fetal aneuploidy.

RESEARCH QUESTION: Do maternal homocysteine (Hcy) concentrations, MTHFR and MTRR genes have effects on the occurrence of fetal aneuploidy? DESIGN: A total of 619 aneuploidy mothers and 192 control mothers were recruited in this study. Differences in distributions of maternal MTHFR 677C>T, MTHFR 1298A>C and MTRR 66A>G genetic polymorphisms and maternal Hcy concentrations between aneuploidy mothers and control mothers were analysed. RESULTS: The maternal MTHFR 677C>T polymorphism was found to be a risk factor for the occurrence of many fetal non-mosaic aneuploidies studied here, including trisomies 13, 15, 16, 18, 21, 22, TRA and TS. The maternal MTHFR 1298A>C polymorphism was found to be a risk factor specifically associated with the occurrence of fetal trisomy 15 and fetal TS. The maternal MTRR 66A>G polymorphism was found to be a risk factor only specifically associated with the occurrence of fetal trisomy 21. The Hcy concentrations of mothers of trisomies 22, 21, 18, 16, 15 and TS fetuses were significantly higher than the Hcy concentrations of control mothers. CONCLUSIONS: Overall, data suggested an association between these maternal polymorphisms and the susceptibility of fetal non-mosaic trisomy and Turner syndrome. However, these three maternal polymorphisms had different associations with the susceptibility of different fetal aneuploidies, and the elevated maternal Hcy concentration appeared to be a likely risk factor for fetal Turner syndrome and fetal trisomies.

[Analysis of CNTNAP1 gene variants in a Chinese pedigree affected with lethal congenital contracture syndrome type 7].

OBJECTIVE: To explore the genetic basis for a couple who had developed polyhydramnios during three pregnancies and given birth to two liveborns featuring limb contracture, dyspnea and neonatal death. METHODS: Whole-exome sequencing (WES) was carried out on fetal tissue and peripheral blood samples from the couple. Suspected variants were verified by Sanger sequencing. RESULTS: The fetus was found to harbor homozygous nonsense c.3718C>T (p.Arg1240Ter) variants of the CNTNAP1 gene, which were respectively inherited from its mother and father. The variant was unreported previously. According to the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be pathogenic (PVS1+PM2+PP4). CONCLUSION: The novel homozygous nonsense variants of the CNTNAP1 gene probably underlay the lethal congenital contracture syndrome type 7 (LCCS7) in this pedigree. Above finding has enabled genetic counseling and prenatal diagnosis for the family.

[Analysis of a Chinese pedigree affected with dyschromatosis symmetrica hereditaria due to a novel variant of ADAR gene].

OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with dyschromatosis symmetrica hereditaria (DSH). METHODS: PCR and Sanger sequencing were carried out for the proband, and suspected variant was validated by Sanger sequencing in the pedigree. RESULTS: The proband was found to harbor a novel variant of c.1352delA (p.N451Mfs*13) of the ADAR (NM_001111) gene. The same variant was found in her affected mother and sister, but not in her unaffected father, uncle, and 100 healthy individual. CONCLUSION: The novel variant of the ADAR gene probably underlay the pathogenesis of DSH in this pedigree.

[Genetic analysis and prenatal diagnosis of a Chinese pedigree affected with Usher syndrome due to novel compound heterozygous variants of PCDH15 gene].

OBJECTIVE: To analyze the clinical features and genetic variant in a patient with Usher syndrome. METHODS: Whole exome sequencing was carried out for the patient. Suspected variants were validated by Sanger sequencing of her parents and fetus. RESULTS: The proband was found to harbor compound heterozygous variants c.17_18insA (p.Tyr6Ter*) and c.4095_4096insA (p.Arg1366Lys fs*38) of the PCDH15 gene (NM_033056), which were respectively inherited from her father and mother. The same variants were not detected in 100 healthy controls. Based on the guidelines of the American Society of Medical Genetics and Genomics, both variants were predicted to be pathogenic (PVS1+PM2+PP4). By prenatal diagnosis, her fetus was found to carry the c.4095_4096insA variant. After birth, the child has passed neonatal hearing screening test, and no abnormal auditory and visual function was found after the first year. CONCLUSION: The compound heterozygous variants c.17_18insA (p.Tyr6Ter*) and c.4095_4096insA (p.Arg1366Lys fs*38) of the PCDH15 gene probably underlay the Usher syndrome is this proband.

Obstetric outcomes for twins from different conception methods - A multicenter cross-sectional study from China.

INTRODUCTION: The effects of assisted reproductive technology on the outcomes of twin pregnancies are controversial. Therefore, the purpose of this study was to compare the maternal and perinatal outcomes of twin pregnancies conceived spontaneously and those conceived by assisted reproductive technology. MATERIAL AND METHODS: This was a cross-sectional study performed at Peking Union Medical College Hospital (PUMCH). Data on twin pregnancies (conceived spontaneously and by in vitro fertilization [IVF]/intracytoplasmic sperm injection [ICSI]) were obtained from the National Birth Registry of China for the period between 1 October 2016, and 30 September 2017. The primary obstetric outcomes were compared between twin pregnancies conceived by different methods. Logistic regression analysis with 95% confidence intervals (95% CI) was used for the multivariate analysis. RESULTS: A total of 3270 twin pregnancies (2003 and 1209 conceived spontaneously and by IVF/ICSI, respectively) were identified. The proportion of twin pregnancies among all pregnancies was 3.4% (3332/97 278). Multiple regression analysis indicated that the incidences of gestational diabetes mellitus (adjusted odds ratio [AOR] = 1.42, 95% CI 1.10-1.83, p = 0.007), preterm premature rupture of membranes (AOR = 1.65, 95% CI 1.21-2.25, p = 0.002), placenta accreta spectrum (AOR = 2.12, 95% CI 1.42-3.17, p < 0.001) and postpartum hemorrhage (AOR = 1.38, 95% CI 1.02-1.86, p = 0.037) were significantly higher in the IVF/ICSI group than in the natural pregnancy group. Multivariate analysis also revealed that conception mode was not an independent risk factor for neonate outcomes. CONCLUSIONS: In twin pregnancies, IVF/ICSI is independently associated with multiple maternal complications, including gestational diabetes mellitus, preterm premature rupture of membranes and placenta accreta spectrum compared with spontaneous conception, although potential residual confounders due to indications for assisted reproductive technology exist.

[Genetic analysis of a pedigree with atypical partial 4q trisomy].

OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with mental retardation. METHODS: G-banded karyotyping analysis and single nucleotide polymorphism microarray (SNP array) were used to detect the genetic variants within the family, and the origin of the variants was analyzed using UPDtool Statistics software. RESULTS: The patient, a 26-year-old female, was found to have a chromosomal karyotype of 46,XX,dup(4)(q28.2q31.3),and SNP array revealed a 25.71 Mb duplication at 4q28.2-q31.3. The duplication was inherited from her father, and her fetus was found to carry the same duplication. CONCLUSION: The duplication of the patient probably underlay the mental retardation. The gender of the carrier and parental origin of the duplication might have led to the variation in their clinical phenotype.

[Identification of SPAST gene variant in a pedigree affected with hereditary spastic paraplegia type 4].

OBJECTIVE: To explore the genetic basis for a pedigree affected with hereditary spastic paraplegia type 4 (HSP4). METHODS: Peripheral venous blood samples were taken from members of the four-generation pedigree and 50 healthy controls for the extraction of genomic DNA. Genes associated with peripheral neuropathy and hereditary spastic paraplegia were captured and subjected to targeted capture and next-generation sequencing. The results were confirmed by Sanger sequencing. RESULTS: DNA sequencing suggested that the proband has carried a heterozygous c.1196C>G variant in exon 9 of the SPAST gene, which can cause substitution of serine by threonine at position 399 (p.Ser399Trp) and lead to change in the protein function. The same variant was also detected in other patients from the pedigree but not among unaffected individuals or the 50 healthy controls. Based on the ACMG 2015 guidelines, the variant was predicted to be possibly pathogenic. CONCLUSION: The c.1196C>G variant of the SPAST gene probably underlay the HSP4 in this pedigree.