Genetic analysis of two children with developmental delay and intellectual disability / 中华医学遗传学杂志

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.

Clinical and genetic analysis of a fetus with 17q12 microdeletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical phenotype and genetic characteristics of a fetus with 17q12 microdeletion syndrome.@*METHODS@#A fetus with 17q12 microdeletion syndrome who was diagnosed at Huzhou Maternal & Child Health Care Hospital in June 2020 was selected as the study subject. Clinical data of the fetus was collected. The fetus was subjected to chromosomal karyotyping and chromosomal microarray analysis (CMA). To determine the origin of fetal chromosomal abnormality, its parents were also subjected to CMA assay. The postnatal phenotype of the fetus was also investigated.@*RESULTS@#Prenatal ultrasound revealed polyhydramnios and fetal renal dysplasia. The fetus was found to have a normal chromosomal karyotype. CMA has detected a 1.9 Mb deletion in the 17q12 region, which has encompassed five OMIM genes including HNF1B, ACACA, ZNHIT3, CCL3L1 and PIGW. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the 17q12 microdeletion was predicted as pathogenic copy number variation (CNV). CMA analysis has detected no pathogenic CNV in both parents. After birth, the child was found to have renal cysts and abnormal brain structure. Combined with the prenatal findings, the child was diagnosed with 17q12 microdeletion syndrome.@*CONCLUSION@#The fetus has 17q12 microdeletion syndrome presenting as abnormalities of the kidney and central nervous system, which are strongly correlated with functional defects of the deletion region involving the HNF1B and other pathogenic genes.

The value of chromosomal microarray analysis and fluorescence in situ hybridization for the prenatal diagnosis of chromosomal mosaicisms / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) for the prenatal diagnosis of chromosomal mosaicisms.@*METHODS@#A total of 775 pregnant women who had visited the Prenatal Diagnosis Center of Yancheng Maternal and Child Health Care Hospital from January 2018 to December 2020 were selected as study subjects. Chromosome karyotyping analysis and CMA were carried out for all women, and FISH was used to validate the suspected mosaicism cases.@*RESULTS@#Among the 775 amniotic fluid samples, karyotyping has identified 13 mosaicism cases, which yielded a detection rate of 1.55%. Respectively, there were 4, 3, 4 and 2 cases for sex chromosome number mosaicisms, abnormal sex chromosome structure mosaicisms, abnormal autosomal number mosaicisms and abnormal autosomal structure mosaicisms. CMA has only detected only 6 of the 13 cases. Among 3 cases verified by FISH, 2 cases were consistent with the karyotyping and CMA results, and clearly showed low proportion mosaicism, and 1 case was consistent with the result of karyotyping but with a normal result by CMA. Eight pregnant women had chosen to terminate the pregnancy (5 with sex chromosome mosaicisms and 3 with autosomal mosaicisms).@*CONCLUSION@#For fetuses suspected for chromosomal mosaicisms, CMA, FISH and G-banding karyotyping should be combined to determine the type and proportion of mosaicisms more precisely in order to provide more information for genetic counseling.

Genetic analysis of a fetus with mosaic trisomy 12 and severe heart defects and a literature review / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus with severe heart defect and mosaic trisomy 12, and the correlation between chromosomal abnormalities and clinical manifestations and pregnancy outcome.@*METHODS@#A 33-year-old pregnant woman who presented at Lianyungang Maternal and Child Health Care Hospital on May 17, 2021 due to abnormal fetal heart development revealed by ultrasonography was selected as the study subject. Clinical data of the fetus were collected. Amniotic fluid sample of the pregnant women was collected and subjected to G-banded chromosomal karyotyping and chromosomal microarray analysis (CMA). The CNKI, WanFang and PubMed databases were searched with key words, with the retrieval period set as from June 1, 1992 to June 1, 2022.@*RESULTS@#For the 33-year-old pregnant woman, ultrasonography at 22+6 gestational weeks had revealed abnormal fetal heart development and ectopic pulmonary vein drainage. G-banded karyotyping showed that the fetus has a karyotype of mos 47,XX,+12[1]/46,XX[73], with the mosaicism rate being 1.35%. CMA results suggested that about 18% of fetal chromosome 12 was trisomic. A newborn was delivered at 39 weeks of gestation. Follow-up confirmed severe congenital heart disease, small head circumference, low-set ears and auricular deformity. The infant had died 3 months later. The database search has retrieved 9 reports. Literature review suggested that the liveborn infants with mosaic trisomy 12 had diverse clinical manifestations depending on the affected organs, which had included congenital heart disease and/or other organs and facial dysmorphisms, resulting in adverse pregnancy outcomes.@*CONCLUSION@#Trisomy 12 mosaicism is an important factor for severe heart defects. The results of ultrasound examination have important value for evaluating the prognosis of the affected fetuses.

Analysis of genetic etiology and related factors in 1 065 women with spontaneous abortions / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology and related factors in 1 065 women with spontaneous abortions.@*METHODS@#All patients have presented at the Center of Prenatal Diagnosis of Nanjing Drum Tower Hospital from January 2018 to December 2021. Chorionic villi and fetal skin samples were collected, and the genomic DNA was assayed by chromosomal microarray analysis (CMA). For 10 couples with recurrent spontaneous abortions but normal CMA results for abortive tissues, non-in vitro fertilization-embryo transfer (IVF-ET) pregnancies and no previous history of live births and no structural abnormalities of the uterus, peripheral venous blood samples were collected. Genomic DNA was subjected to trio-whole exome sequencing (trio-WES). Candidate variants were verified by Sanger sequencing and bioinformatics analysis. Multifactorial unconditional logistic regression analysis was carried out to analyze the factors that may affect chromosomal abnormality in spontaneous abortions, such as the age of the couple, number of previous spontaneous abortions, IVF-ET pregnancy and history of live birth. The incidence of chromosomal aneuploidies in spontaneous abortions during the first trimester was compared in young or advanced-aged patients by chi-square test for liner trend.@*RESULTS@#Among the 1 065 spontaneous abortion patients, 570 cases (53.5%) of chromosomal abnormalities were detected in spontaneous abortion tissues, which included 489 cases (45.9%) of chromosomal aneuploidies and 36 cases (3.4%) of pathogenic/likely pathogenic copy number variations (CNVs). Trio-WES results have revealed one homozygote variant and one compound heterozygote variants in two pedigrees, both of which were inherited from the parents. One likely pathogenic variant was detected in the patient from two pedigrees. Multifactorial unconditional Logistic regression analysis suggested that age of patient was an independent risk factor of chromosome abnormalities (OR = 1.122, 95%CI: 1.069-1.177, P < 0.001), the number of previous abortions and IVF-ET pregnancy were independent protective factors for chromosomal abnormalities (OR = 0.791, 0.648; 95%CI: 0.682-0.916, 0.500-0.840; P = 0.002, 0.001), whilst the age of husband and history of live birth were not (P > 0.05). The incidence of aneuploidies in the abortive tissues has decreased with the number of previous spontaneous abortions in young patients (χ² = 18.051, P < 0.001), but was not significantly correlated with the number of previous spontaneous abortions in advanced-aged patients with spontaneous abortions (P > 0.05).@*CONCLUSION@#Chromosomal aneuploidy is the main genetic factor for spontaneous abortion, though CNVs and genetic variants may also underlie its genetic etiology. The age of patients, number of previous abortions and IVF-ET pregnancy are closely associated with chromosome abnormalities in abortive tissues.

Expert consensus on the detection of genome-wide copy number variations in abortive tissues and family reproductive consultation / 中华医学遗传学杂志

Chromosomal aberrations including numerical abnormalities and segment duplications/deletions, as genome-wide copy number variations (CNVs), are a leading cause for spontaneous abortion. Analysis of abortive tissues for such CNVs can detect potential genomic variations in the couple and provide guidance for the choice of appropriate method to avoid further miscarriage or birth of child with chromosomal disorders. With evidence-based clinical data, an expert group jointly formed by the Genetic Disease Prevention and Control Group, Committee for Birth Defects Prevention and Control, Chinese Association of Preventive Medicine; the Clinical Genetics Group, the Society of Medical Genetics, Chinese Medical Association; the Professional Committee for Prenatal Diagnosis of Genetic Diseases, the Society of Medical Geneticists, Chinese Medical Doctor Association has discussed and formulated this consensus, with an aim to provide guidance for the application of genomic CNVs detection for the abortive tissue and genetic counseling for family reproduction.

Application value of CNV-seq for the prenatal diagnosis of women with high-risk pregnancies / 中华医学遗传学杂志

OBJECTIVE@#To assess the application value of copy number variation sequencing (CNV-seq) for women with a high risk for fetal anomalies.@*METHODS@#Based on the results of non-invasive prenatal testing (NIPT), 271 high-risk pregnant women were divided into NIPT positive group (n = 83) and other anomaly group (advanced age, high risk by serological screening, repeated NIPT failure, adverse pregnancy history, abnormal ultrasound finding, and abnormal phenotype) (n = 188). CNV-seq was carried out to detect copy number variations (CNVs) in amniocytic DNA from the two groups of pregnant women, and karyotyping analysis of the amniotic cells was carried out for verification and comparison.@*RESULTS@#The amniocytes from 271 pregnant women were detected. The detection rate was 20.66% (56/271) for pathogenic CNVs by CNV-seq and 19.19% (52/271) for pathogenic karyotypes by karyotyping analysis. The difference was statistically significant (P < 0.05). CNV-seq had shown that, compared with NIPT positive group, the detection rates for likely pathogenic CNVs and variants of unknown significance (VUS) in other abnormality group were significantly higher [2.41%(2/83) vs. 5.32%(10/188)](P < 0.05).@*CONCLUSION@#CNV-seq can well suit the first-tier diagnosis for pregnant women suspected for fetal abnormality. In prenatal diagnosis settings, CNV-seq can identify additional and clinically significant cytogenetic abnormalities. In those with other abnormalities, the detection rates for likely pathogenic CNVs and VUS are higher than with the NIPT positive cases.

Genetic testing and analysis of 2 cases of trisomy 11 mosaicism / 南方医科大学学报

Trisomy 11 mosaicism is clinically rare, for which making diagnostic and treatment decisions can be challenging. In this study, we used noninvasive prenatal testing, chromosome karyotype analysis, chromosome microarray analysis, copy number variation sequencing and fluorescence in situ hybridization for detecting trisomy 11 mosaicism in two cases and provided them with genetic counseling. In one of the cases, the fetus with confined placental mosaicism trisomy 11 presented with severe growth restriction and a placental mosaic level of 44%, and pregnancy was terminated at 25+3 weeks of gestation. In the other case with true low-level fetal mosaicism of trisomy 11, the pregnancy continued after exclusion of the possibility of uniparental disomy and structural abnormalities and careful prenatal counseling. The newborn was followed up for more than one year, and no abnormality was found. Noninvasive prenatal testing is capable of detecting chromosomal mosaicism but may cause missed diagnosis of true fetal mosaicism. For cases with positive noninvasive prenatal testing but a normal karyotype of the fetus, care should be taken in prenatal counseling and pregnancy management.

A rare case of dicentric ring chromosome and derivative ring chromosome Chimera / 中华医学遗传学杂志

OBJECTIVE@#Utilize high-resolution chromosome analysis and microarray detection to determine the genetic etiology of infertility of a 32-year old female patient.@*METHODS@#The peripheral blood of the patient was cultured for high-resolution chromosome G and C banding karyotype analysis, and then 750K SNP-Array chip detection was performed.@*RESULTS@#Karyotype analysis results showed that the patient's karyotype was 45,XX,-13 [7]/46,XX,r(13) (p13q34) [185]/46,XX,dic r(13;13)(p13q34;p13q34) [14]/ 47,XX,+der(13;13;13;13) (p13q34;p13q34;p13q34; p13q34), dic r(13;13) [1]/ 46,XX [3]. The microarray results showed that the patient had a 3.3 Mb deletion in the 13q34 segment of chromosome 13, which may be related to infertility.@*CONCLUSION@#Infertility of the patient reported in this article may be related to the deletion of chromosome segment (13q34-qter).

Application of CNV-seq and chromosomal karyotyping in the prenatal diagnosis for carriers of balanced translocations / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of copy number variation sequencing (CNV-seq) and karyotyping in the prenatal diagnosis for carriers of balanced translocations.@*METHODS@#Clinical records of 135 amniocentesis samples of balanced translocation carriers undergoing simultaneous CNV-seq and karyotyping were analyzed. Chromosomal aberrations were defined as those can definitely lead to birth defects definitely, which included chromosomal numerical abnormality, large deletion/duplication and pathogenic copy number variations (pCNVs).@*RESULTS@#The detection rates for karyotyping and CNV-seq were 4.44% (6/135) and 5.93% (8/135) respectively, and the latter had a detection rate of 1.48(2/135) higher than the former. A total of 68 fetal chromosomal translocations were detected by karyotying analysis.@*CONCLUSION@#For couples carrying a balanced translocation, simultaneous CNV-seq and karyotyping is conducive to the detection of fetal chromosomal abnormalities and genetic counseling.

Genetic analysis of a case with mosaicism of a small supernumerary marker chromosome derived from idic(15) / 中华医学遗传学杂志

OBJECTIVE@#To determine the origin of a mosaicism small supernumerary marker chromosome (sSMC) by cytogenetic and molecular analysis.@*METHODS@#Karyotype analysis, fluorescence in situ hybridization (FISH) and SNP-array were carried out.@*RESULTS@#The karyotype of the patient was mos47,XX,+mar[45]/48,XX,+2mar[3]/46,XX[52]; the SNP-array result was arr[hg19]15q11.1q11.2 (20 161 372-24 314 675)×3, and the repeat fragment was about 4.15 Mb. FISH showed that approximately 50% of the cells have contained a sSMC with double D15Z1 probe site segments derived from abnormal idic(15). This sSMC did not contain SNRPN and PML probe fragments of Prader-Willi syndrome/Angelman syndrome.@*CONCLUSION@#When the patient's karyotype and phenotype are inconsistent, cytogenetic and molecular biology technologies should be combined to clarify the karyotype and gene location, so as to provide more accurate genetic consultation for the follow-up treatments.

Uleritema ofriógenes como entidad asociada al síndrome 18p- en un paciente pediátrico / Ulerythema ophryogenes as an entity associated with 18p- syndrome in a pediatric patient

El uleritema ofriógenes es un trastorno cutáneo benigno y poco frecuente que se presenta habitualmente en la infancia. Se caracteriza por pápulas foliculares eritematosas y queratósicas en el lateral de las cejas, que con el tiempo suelen evolucionar a alopecia cicatricial. Dicha entidad puede aparecer como manifestación clínica aislada o asociada a varios síndromes congénitos (18p-, Cornelia de Lange, Noonan y Rubinstein- Taybi, entre otros). Presentamos el caso de un paciente de 13 años con síndrome 18p- que consultó por lesiones puntiformes rugosas al tacto y pérdida de pelo en ambas cejas (uleritema ofriógenes), así como por hiperqueratosis pilar en brazos. Esta tríada, conocida como síndrome de Zouboulis, ha sido poco descrita en la literatura. Se considera que el reconocimiento del uleritema ofriógenes es de crucial importancia ya que, ante su presencia, debería realizarse una anamnesis y una exploración física exhaustivas en búsqueda de otras alteraciones que pudieran orientar a la existencia de un trastorno genético subyacente.

Ulerythema ophryogenes is a benign and rare skin disorder commonly presenting in childhood. It is characterized by erythematous and keratotic follicular papules located on the side of the eyebrows, and which over time tends to evolve into scarred alopecia. This entity may appear as an isolated clinical manifestation or associated with several congenital syndromes (18p-, Cornelia de Lange, Noonan, Rubinstein-Taybi, among others). We present a 13-year-old male with 18p- syndrome who consults for rough lesions and hair loss in both eyebrows (ulerythema ophryogenes), as well as for hyperkeatosis pilaris in both arms. This triad, known as Zouboulis syndrome, has been rarely reported in the literature. We consider that the recognition of ulerythema ophryogenes is of crucial importance since, in view of its presence, comprehensive anamnesis and physical examination should be performed in search of other alterations that could guide the existence of an underlying genetic disord

Reporte de malformaciones fetales diagnosticadas en comité ecográfico del Hospital Regional de Talca, entre junio 2020 y junio 2021 / Report of fetal malformations diagnosed in the ultrasound committee of the regional hospital of Talca, between june 2020 and june 2021

Introduction: Obstetric ultrasound is part of the screening to select the population at high risk of having a congenital malformation. Considering that fetal defects occur in approximately 2-4 out of every 100 live newborns, and are the cause of 35-40% of perinatal mortality in Chile, it is therefore justified to perform the second trimester ultrasound, which presents a high index prenatal screening (56%), with few false positives. Methods: A retrospective, cross-sectional and descriptive study was carried out, by reviewing 6,385 ultrasound scans, which were performed during one year (June 2020-June 2021), at the Regional Hospital of Talca, where 126 fetuses with suspected malformation were detected. Results: Of the total number of patients evaluated, a congenital malformation rate of 1.9% was detected, with cardiac malformations the most frequent, and diabetes mellitus the main risk factor. Conclusions: Antenatal ultrasound study is essential in the first and second trimesters of pregnancy, followed by a referral to an ultrasound committee, emphasizing early and interdisciplinary management. The frequencies found are similar to those reported in the international bibliography

Síndrome de Rubinstein ­ Taybi: características fenotípicas, reporte de caso / Rubinstein - Taybi syndrome: phenotypic characteristics, case report / Síndrome de Rubinstein - Taybi: características fenotípicas, relato de caso

Introducción: El síndrome de Rubinstein ­ Taybi es una patología de origen genético que afecta a 1 de cada 100.000 a 125.000 nacidos vivos, se caracteriza por presentar: retraso en el crecimiento, retraso en el desarrollo psicomotriz y anomalías morfológicas que incluyen: rasgos faciales peculiares (cejas arqueadas y gruesas, fisuras palpebrales inclinadas hacia abajo, puente nasal convexo con punta de la nariz por debajo de las alas), pulgares y hallux anchos. Su origen epigenético en el 60% de los casos se debe a una alteración en el gen CREBBP (codificador de la proteína CPB), en el 10% a un cambio en el gen EP300 (codificador de la proteína p300) y en el 30% no se han logrado identificar su causa. Caso clínico: Niño de 8 años de edad con retardo en el desarrollo psicomotriz, con dificultades para la adaptación escolar. Al examen físico con rasgos faciales: cejas superpobladas y arqueadas, hirsutismo en frente y región de labio superior, fisuras palpebrales inclinadas hacia abajo, hipertelorismo con estrabismo convergente, puente nasal ancho, nariz achatada, la punta se extiende levemente por debajo de las alas nasales. Con hirsutismo en región cervical e interescapular. En las manos se identifica dedos pulgares anchos, en el resto de dedos se evidencian falanges distales ensanchadas, de igual forma en la región de los pies se identifican hallux anchos y falanges distales ensanchadas. Evolución: El paciente sigue en observación por consulta externa, fue enviado a programas de terapia de lenguaje, lectura y psicomotriz. No ha desarrollado infecciones pulmonares hasta el cierre del seguimiento, 6 meses posteriores al diagnóstico. Conclusión: En presente caso reporta las alteraciones fenotípicas características faciales y de extremidades de un niño con síndrome de Rubinstein-Taybi, las cuales ayudaron al diagnóstico clínico.

Introduction: Rubinstein-Taybi syndrome is a pathology of genetic origin that affects 1 out of every 100,000 to 125,000 live births, it is characterized by: growth retardation, delay in psy-chomotor development and morphological abnormalities that include: peculiar facial features (thick arched eyebrows, downward sloping palpebral fissures, convex nasal bridge with tip of nose below wings), broad thumbs and hallux. Its epigenetic origin in 60% of cases is due to an alteration in the CREBBP gene (coding for CPB protein), in 10% to a change in the EP300 gene (coding for p300 protein) and in the 30% have not been able to identify its cause. Clinical case: 8-year-old boy with a delay in psychomotor development, with difficulties in adapting to school. On physical examination with facial features: overpopulated and arched eyebrows, hirsutism in the forehead and upper lip region, downward sloping palpebral fissures, hypertelorism with convergent strabismus, wide nasal bridge, flattened nose, the tip extends slightly below the nasal wings. With hirsutism in the cervical and interscapular region. In the hands, broad thumbs are identified, in the rest of the fingers there are widened distal phalanges, in the same way in the region of the feet, wide hallux and widened distal phalanges are identified. Evolution: The patient continues to be observed by outpatient consultation, he was sent to speech, reading and psychomotor therapy programs. He has not developed pulmonary infections until the close of follow-up, 6 months after diagnosis. Conclusion: In this case, it reports the phenotypic alterations of the facial and limb characteristics of a child with Rubinstein-Taybi syndrome, which helped the clinical diagnosis.

Introdução: A síndrome de Rubinstein-Taybi é uma patologia de origem genética que afeta 1 em cada 100.000 a 125.000 nascidos vivos, é caracterizada por: retardo de crescimento, atraso no desenvolvimento psicomotor e anormalidades morfológicas que incluem: características faciais peculiares (sobrancelhas arqueadas e grossas, descendente fissuras palpebrais, ponte nasal convexa com a ponta do nariz abaixo das asas), polegares largos e hálux. Sua origem epigenética em 60% dos casos deve-se a uma alteração no gene CREBBP (que codifica a proteína CPB), em 10% a uma alteração no gene EP300 (que codifica a proteína p300) e em 30% sua causa não foi identificada . Caso clínico: Menino de 8 anos com atraso no desenvolvimento psicomotor, com dificuldade de adaptação à escola. No exame físico com características faciais: sobrancelhas superpovoadas e arqueadas, hirsutismo na testa e região do lábio superior, fissuras palpebrais inclinadas para baixo, hipertelorismo com estrabismo convergente, ponte nasal larga, nariz achatado, a ponta se estende ligeiramente abaixo das asas nasais. Com hirsutismo na região cervical e interescapular. Nas mãos identificam-se os polegares largos, nos restantes dedos são identificadas falanges distais alargadas, da mesma forma que na região dos pés, hálux largo e falanges distais alargadas. Evolução: O paciente ainda está em acompanhamento ambulatorial, foi encaminhado para programas de fonoaudiologia. Ele não desenvolveu infecções pulmonares até o fechamento do acompanhamento, 6 meses após o diagnóstico. Conclusão: Nesse caso, relata as alterações fenotípicas das características faciais e de membros de uma criança com síndrome de Rubinstein-Taybi, o que auxiliou no diagnóstico clínico.

Genetic analysis of a case with MEF2C deletion in association with 5q14.3 microdeletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child with febrile seizures.@*METHODS@#Peripheral venous blood samples were taken from the child and his parents for the analysis of chromosomal karyotype and dynamic variant of the FMR1 gene. The family trio was also subjected to target capture and next generation sequencing (NGS) with a gene panel related to developmental retardation, mental retardation, language retardation, epilepsy and special facial features.@*RESULTS@#The child was found to have a normal karyotype by conventional cytogenetic analysis (400 bands). No abnormal expansion was found with the CGG repeats of the FMR1 gene. NGS revealed that the child has carried a heterozygous c.864+1 delG variant of the MEF2C gene, which may lead to abnormal splicing and affect its protein function. The same variant was found in neither parent, suggesting that it has a de novo origin. Based on the American College of Medical Genetics and Genomics standards and guidelines, c.864+1delG variant of MEF2C gene was predicted to be pathogenic (PVS1+PS2+PM2).@*CONCLUSION@#MEF2C, as the key gene for chromosome 5q14.3 deletion syndrome which was speculated as a cause for febrile seizures, has an autosomal dominant effect. The c.864+1delG variant of the MEF2C gene may account for the febrile seizures in this patient.

Interim In vitro Dose-Response Curve for the Dicentric Biodosimeter Assay from a Philippine Radiotherapy Facility using a Linear Accelerator

@#Background. Accidental radiation exposure can occur anytime. Biodosimeters help in quantifying the absorbed dose of individuals who are not equipped with personal dosimeters during radiation exposure. The dicentric assay can quantify radiation damage by correlating radiation dose exposure with the frequency of dicentric chromosomes in the peripheral lymphocytes extracted from exposed individuals. Objective. The study aims to present the interim results of the reference dose-response curve for a Philippine radiotherapy facility constructed using a 6MV linear accelerator (ClinacX, Varian). Methods. Samples of peripheral blood from healthy volunteers were irradiated in a customized water phantom of doses 0.10 to 5.0 Gray using a linear accelerator. The irradiated samples were cultured and analyzed following the International Atomic Energy Agency Cytogenetic Dosimetry Protocol (2011) with modifications. Linear-quadratic model curve fitting and further statistical analysis were done using CABAS (Chromosome Aberration Calculation Software Version 2.0) and Dose Estimate (Version 5.2). Interim results of the samples were used to generate these curves. Results. The dose-response curve generated from the preliminary results were comparable to published dose response curves from international cytogenetic laboratories. Conclusion. The generated dose-response calibration curve will be useful for medical triage of the public and radiologic staff accidentally exposed to radiation during medical procedures or in the event of nuclear accidents.

Genetic analysis of a recurrent abnormal pregnancy case caused by a cryptic reciprocal autosomal translocation / 中华医学遗传学杂志

OBJECTIVE@#To provide genetic counseling for a couple with recurrent detection of fetal structural abnormality during second trimester pregnancy.@*METHODS@#The fetal tissue and peripheral blood samples of the couple were subjected to G banded chromosomal analysis, copy number variation sequencing (CNV-seq) and fluorescence in situ hybridization (FISH) assays.@*RESULTS@#CNV-seq has detected a 6.59 Mb duplication at 7p22.3-p22.1 and a 3.81 Mb deletion at 4p16.3 in the fetal tissue, though conventional karyotyping results of both parents were normal. FISH has confirmed that the father has harbored a cryptic translocation of t(4;7)(7p+,4q+,4p+,7q+).@*CONCLUSION@#The ultrasonographic abnormality of the fetuses may be attributed to the 7p microduplication and 4p microdeletion derived from the cryptic translocation carried by the father. Reciprocal translocation of tiny chromosomal segments should be suspected for couples with recurrent adverse pregnancies but apparently normal karyotypes.

Clinical phenotype and genetic analysis of a case of 5q14.3 microdeletion syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical features and genetic characteristics of a child with 5q14.3 microdeletion syndrome.@*METHODS@#Whole exome sequencing (WES) and low-coverage massively parallel copy number variation sequencing (CNV-seq) were used to determine the potentially pathogenic variants as well as the copy number variations (CNVs). Candidate CNVs were verified by real-time fluorescence quantitative PCR.@*RESULTS@#The patient presented with psychomotor retardation, epilepsy, peculiar face and hypotonia. The results of WES suggested that he has carried a heterozygous deletion for chr5:86 564 268-88 119 605. CNV-seq indicated that the patient carried a heterozygous deletion of 4.76 Mb heterozygous deletion on chromosome 5q14.3. The MEF2C gene and RASA1 gene in the deletion area were verified by real-time fluorescence quantitative PCR. The results showed that the MEF2C geneand RASA1 gene were heterozygous deletion, which was consistent with the sequencing results.@*CONCLUSION@#The child was diagnosed with 5q14.3 microdeletion syndrome. Haploinsufficiency of the MEF2C gene may underlie the manifestations of 5q14.3 microdeletion syndrome.

Analysis of the results of chromosomal trisomies 21, 18 and 13 screening among 40 628 women by non-invasive prenatal testing / 中华医学遗传学杂志

OBJECTIVE@#To assess the clinical value of non-invasive prenatal testing (NIPT) for the screening of trisomy and copy number variations (CNVs) of chromosomes 21, 18 and 13.@*METHODS@#From January 2015 to December 2019, 40 628 pregnant women underwent NIPT testing using high-throughput sequencing and bioinformatics analysis to test the cell-free fetal DNA in maternal plasma. High-risk pregnant women underwent invasive prenatal diagnosis, while low-risk ones were followed up by telephone.@*RESULTS@#The three most common indications included intermediate risk of serological screening, high risk of serological screening and advanced maternal age. Among all pregnant women, 257 cases were detected as trisomy 21, 18 and 13 (170, 49 and 38 cases, respectively). 227 cases chose invasive prenatal diagnosis, with respectively 122, 28 and 10 cases confirmed. The positive predictive value (PPV) was 81.33% (122/150), 65.12% (28/43), 29.41% (10/34), respectively. Two false negative cases of trisomy 18 were found during follow-up. Meanwhile, NIPT has detected 46 cases (15, 16 and 15 cases, respectively) CNVs on chromosomes 21, 18 and 13, among which 37 cases underwent invasive prenatal diagnosis. There were 5, 3 and 5 positive cases, which yielded a PPV of 41.67% (5/12), 25%(3/12) and 33.33%(5/15), respectively. Two other chromosome CNVs were accidentally discovered among the false positive samples.@*CONCLUSION@#The incidence of chromosomal abnormalities in the serological screening high-risk group was 52.02%, which was significantly higher than other groups. NIPT has a high sensitivity and specificity for the screening of trisomies 21, 18 and 13, while its accuracy for detecting CNVs of chromosomes 21, 18 and 13 needs to be improved. As a screening method, NIPT has a great clinical value, though there are still limitations of false positive and false negative results.Comprehensive pre- and post-test genetic counseling should be provided to the patients.

Non-invasive prenatal testing and genetic diagnosis of a case of Pallister-Killian syndrome / 中华医学遗传学杂志

OBJECTIVE@#To apply combined non-invasive prenatal testing (NIPT), chromosomal karyotyping and chromosomal microarray for the screening and prenatal diagnosis of a fetus with supernumerary small marker chromosome (sSMC).@*METHODS@#Standard NIFTY and full gene NIFTY kits were applied to detect free DNA (cfDNA) isolated from peripheral blood sample of a pregnancy woman. Amniocentesis was carried out for the woman for an abnormal NIPT result. G-banded karyotyping and single nucleotide polymorphism array (SNP array) were used to determine the karyotype and copy number variants in the fetus. The result was validated with a fluorescence in situ hybridization (FISH) assay.@*RESULTS@#Both the standard NIFTY and full gene NIFTY indicated abnormal dup(chr12:707 334-33 308 759), for which the T score value of copy number anomaly in full gene NIFTY is 6.823, which is higher than the standard NIFTY's T-score value of 3.9535. The two NIFTY results were both above the normal threshold ± 3. Conventional G-banding analysis of amniocytes showed that the fetus has a karyotype of 47,XY,+mar. SNP-array delineated duplication of 12p (arr [hg19]12p13.33p11.1 (173 786_34 385 641)× 4, which was verified by FISH. Based on the above results, the fetus was diagnosed as a novel case of Pallister-Killian syndrome.@*CONCLUSION@#NIPT has a certain value for the prenatal detection of PKS. Combined use of multiple techniques can facilitate delineation of the source of sSMC.