Microduplication Syndrome Research Articles

Partial trisomy 9p and partial monosomy 7p of an infant inherited from maternal balanced translocation: a case report

BackgroundSubchromosomal deletions and duplications are the leading cause of congenital malformations and mental retardation in children. With the recent clinical application of genomic microarrays in the evaluation of patients with developmental delays and congenital malformations, it has led to the discovery of several new microdeletion and microduplication syndromes. However, there are no published reports involving patients with both microduplications in the 9p21.1-p24.3 region and microdeletions in the 7p22.1-p22.3 region.Case presentationWe report an infant with an autosomal abnormality confirmed by conventional karyotype combined with copy number variations sequencing (CNV-seq), showing the patient with an unbalanced translocation. The karyotype of the patient was 46, XX, der (7)t (7;9) (p22; p21) and CNV-seq results showed an approximately 32.34-Mb duplication in 9p21.1-p24.3 (200000-32540000) and an approximately 3.3-Mb deletion in 7p22.2-p22.3 (40000-3340000).ConclusionsThe patient carried an unbalanced translocation 46, XX, der (7)t (7;9) (p22; p21) derived from her mother. The clinical presentation is closely related to the size and position of the missing and duplicated chromosomes. To our knowledge, the simultaneous occurrence of de novo partial trisomy 9p(9p21.1-p24.3) and partial monosomy 7p (7p22.2-p22.3) has not previously been reported up until now. The present study additionally demonstrated that CNV-seq combined with karyotype is able to reliably detect unbalanced submicroscopic chromosomal aberrations.

Clinical and genetic characteristics of 9 rare cases with coexistence of dual genetic diagnoses

Objective: To analyze the clinical and genetic characteristics of pediatric patients with dual genetic diagnoses (DGD). Methods: Clinical and genetic data of pediatric patients with DGD from January 2021 to February 2022 in Peking University First Hospital were collected and analyzed retrospectively. Results: Among the 9 children, 6 were boys and 3 were girls. The age of last visit or follow-up was 5.0 (2.7,6.8) years. The main clinical manifestations included motor retardation, mental retardation, multiple malformations, and skeletal deformity. Cases 1-4 were all all boys, showed myopathic gait, poor running and jumping, and significantly increased level of serum creatine kinase. Disease-causing variations in Duchenne muscular dystrophy (DMD) gene were confirmed by genetic testing. The 4 children were diagnosed with DMD or Becker muscular dystrophy combined with a second genetic disease, including hypertrophic osteoarthropathy, spinal muscular atrophy, fragile X syndrome, and cerebral cavernous malformations type 3, respectively. Cases 5-9 were clinically and genetically diagnosed as COL9A1 gene-related multiple epiphyseal dysplasia type 6 combined with NF1 gene-related neurofibromatosis type 1, COL6A3 gene-related Bethlem myopathy with WNT1 gene-related osteogenesis imperfecta type XV, Turner syndrome (45, X0/46, XX chimera) with TH gene-related Segawa syndrome, Chromosome 22q11.2 microduplication syndrome with DYNC1H1 gene-related autosomal dominant lower extremity-predominant spinal muscular atrophy-1, and ANKRD11 gene-related KBG syndrome combined with IRF2BPL gene-related neurodevelopmental disorder with regression, abnormal movement, language loss and epilepsy. DMD was the most common, and there were 6 autosomal dominant diseases caused by de novo heterozygous pathogenic variations. Conclusions: Pediatric patients with coexistence of double genetic diagnoses show complex phenotypes. When the clinical manifestations and progression are not fully consistent with the diagnosed rare genetic disease, a second rare genetic disease should be considered, and autosomal dominant diseases caused by de novo heterozygous pathogenic variation should be paid attention to. Trio-based whole-exome sequencing combining a variety of molecular genetic tests would be helpful for precise diagnosis.

Sequence Motif Analysis of PRDM9 and Short Inverted Repeats Suggests Their Contribution to Human Microdeletion and Microduplication Syndromes

Holliday junctions are the first recognized templates of legitimate recombination. Their prime physiological role is meiotic homologous recombination, resulting in rearrangements of the genetic material. In humans, recombination hotspots follow a distinct epigenetic pattern designated by the presence of PR domain-containing protein 9 (PRDM9). Repetitive DNA elements can replicate in the genome and can pair with short inverted repeats (SIRs) that form Holliday junctions in a significantly high frequency in vitro. Remarkably, PRDM9 and SIR sequence motifs, which may have the potential to act as recombination primers associated with transposable elements (TEs) and their presence, may lead to gradual spreading of recombination events in human genomes. Microdeletion and microduplication syndromes (MMSs) constitute a significant entity of genetic abnormalities, almost equal in frequency to aneuploidies. Based on our custom database, which includes all MMSs shorter than 5 Mbs in length which is the cut-off point for the standard cytogenetic resolution, we found that the majority of MMSs were present in sequences shorter than 0.5 Mbs. A high probability of TE-associated and non-TE-associated PRDM9/SIR sequence motifs was found in short and long MMSs. Significantly, following the Reactome pathway analysis, a number of affected genes have been associated with the pathophysiological pathways linked to MMSs. In conclusion, PRDM9 or SIR sequence motifs in regions spanning MMSs hotspots underlie a potential functional mechanism for MMS occurrences during recombination.

P130: Case report: Phenotypic features among four first-degree relatives with 17q11.2 microduplication syndrome

P130: Case report: Phenotypic features among four first-degree relatives with 17q11.2 microduplication syndrome

Prenatal diagnosis and genetic analysis of three fetuses with paternal chromosomal simplex 3q microduplication syndrome

To explore the phenotypic characteristics of paternal chromosomal simplex 3q microduplication syndrome. Amniotic fluid samples of 3 fetuses from a same couple were subjected to prenatal diagnosis through combined high-resolution chromosomal G-banding karyotyping and chromosomal microarray analysis (CMA). Peripheral blood samples were also collected the couple for the determination of parental origin. The karyotypes of all three fetuses were 46,XN,dup(3)(q25q26.1), and their CMA results were arr[hg19]3q25.33q26.1(159 336 333-166 924 969)×3. The duplication in the three fetuses have all derived from their father. No anomaly with found with the mother by CMA . Through combined G-banded chromosomal karyotyping and CMA assay, a paternally derived 3q25.33-q26.1 microduplication has been identified, which has enabled genetic counseling for this couple.

Efficiency of expanded noninvasive prenatal testing in the detection of fetal subchromosomal microdeletion and microduplication in a cohort of 31,256 single pregnancies

Noninvasive prenatal testing (NIPT) is widely used to screen for common fetal chromosomal aneuploidies. However, the ability of NIPT-Plus to detect copy number variation (CNV) is debatable. Accordingly, we assessed the efficiency of NIPT-Plus to detect clinically significant fetal CNV. We performed a prospective analysis of 31,260 singleton pregnancies, included from June 2017 to December 2020. Cell-free fetal DNA was directly sequenced using the semiconductor sequencing platform for women with high-risk CNV with clinically significant results. Fetal karyotyping and chromosomal microarray analysis (or next-generation sequencing) are recommended for invasive diagnostic procedures. Women at low risk with no other abnormal results continued their pregnancies. We analyzed the expanded NIPT results, diagnostic test results, and follow-up information to evaluate its performance in detecting fetal CNV. Of the 31,260 pregnant women who received NIPT-Plus, 31,256 cases were tested successfully, a high risk of clinically significant CNV was detected in 221 cases (0.71%); 18 women refused further diagnosis; 203 women underwent invasive prenatal diagnosis; and 78 true positive cases and 125 false positive cases, with an overall positive predictive value (PPV) of 38.42% and a false positive rate of 0.40%. For known microdeletion/microduplication syndromes (n = 27), the PPVs were 75% DiGeorge syndrome (DGS), 80% 22q11.22 microduplication, 50% Prader–Willi syndrome, and 50% cri-du-chat. For the remaining clinically significant fetal CNVs (n = 175), the combined PPVs were 46.5% (CNVs > 10 Mb) and 28.57% (CNVs ≤ 10 Mb). NIPT-Plus screening for CNV has certain clinical value. NIPT-Plus yielded relatively high PPVs for 22q11.2 microduplication syndrome and DGS, and low to moderate PPVs for other CNVs.

A rigorous in silico genomic interrogation at 1p13.3 reveals 16 autosomal dominant candidate genes in syndromic neurodevelopmental disorders.

Genome-wide chromosomal microarray is extensively used to detect copy number variations (CNVs), which can diagnose microdeletion and microduplication syndromes. These small unbalanced chromosomal structural rearrangements ranging from 1 kb to 10 Mb comprise up to 15% of human mutations leading to monogenic or contiguous genomic disorders. Albeit rare, CNVs at 1p13.3 cause a variety of neurodevelopmental disorders (NDDs) including development delay (DD), intellectual disability (ID), autism, epilepsy, and craniofacial anomalies (CFA). Most of the 1p13.3 CNV cases reported in the pre-microarray era encompassed a large number of genes and lacked the demarcating genomic coordinates, hampering the discovery of positional candidate genes within the boundaries. In this study, we present four subjects with 1p13.3 microdeletions displaying DD, ID, autism, epilepsy, and CFA. In silico comparative genomic mapping with three previously reported subjects with CNVs and 22 unreported DECIPHER CNV cases has resulted in the identification of four different sub-genomic loci harboring five positional candidate genes for DD, ID, and CFA at 1p13.3. Most of these genes have pathogenic variants reported, and their interacting genes are involved in NDDs. RT-qPCR in various human tissues revealed a high expression pattern in the brain and fetal brain, supporting their functional roles in NDDs. Interrogation of variant databases and interacting protein partners led to the identification of another set of 11 potential candidate genes, which might have been dysregulated by the position effect of these CNVs at 1p13.3. Our studies define 1p13.3 as a genomic region harboring 16 NDD candidate genes and underscore the critical roles of small CNVs in in silico comparative genomic mapping for disease gene discovery. Our candidate genes will help accelerate the isolation of pathogenic heterozygous variants from exome/genome sequencing (ES/GS) databases.

Clinical and genomic delineation of the new proximal 19p13.3 microduplication syndrome.

A small but growing body of scientific literature is emerging about clinical findings in patients with 19p13.3 microdeletion or duplication. Recently, a proximal 19p13.3 microduplication syndrome was described, associated with growth delay, microcephaly, psychomotor delay and dysmorphic features. The aim of our study was to better characterize the syndrome associated with duplications in the proximal 19p13.3 region (prox 19p13.3 dup), and to propose a comprehensive analysis of the underlying genomic mechanism. We report the largest cohort of patients with prox 19p13.3 dup through a collaborative study. We collected 24 new patients with terminal or interstitial 19p13.3 duplication characterized by array-based Comparative Genomic Hybridization (aCGH). We performed mapping, phenotype-genotype correlations analysis, critical region delineation and explored three-dimensional chromatin interactions by analyzing Topologically Associating Domains (TADs). We define a new 377 kb critical region (CR 1) in chr19: 3,116,922-3,494,377, GRCh37, different from the previously described critical region (CR 2). The new 377 kb CR 1 includes a TAD boundary and two enhancers whose common target is PIAS4. We hypothesize that duplications of CR 1 are responsible for tridimensional structural abnormalities by TAD disruption and misregulation of genes essentials for the control of head circumference during development, by breaking down the interactions between enhancers and the corresponding targeted gene.

VP.09 Clinical characteristics and gene analysis of 10 rare cases with coexistence of double genetic diseases

Coexistence of double genetic diseases in one patient is quite rare. In this study, we aimed to analyse the clinical and genetic characteristics of patients with double genetic diseases. Clinical and genetical data of patients with double genetic diseases from January 2021 to February 2022 in Peking University First Hospital were collected and analyzed. Among these 10 children, 7 were boys and 3 were girls, with last follow-up ages ranging from 2.0 to 7.9 years old. Cases 1-5, all boys, showed myopathic gait, poor running and jumping, and significantly increased serum creatine kinase level, as well as pathogenic variations in DMD gene, and were diagnosed as DMD/BMD. However, all of them had other symptoms and signs that were inconsistent with DMD/BMD. Further trio-based whole exome sequencing was performed. The 5 patients also had a second genetic disease, including hypertrophic osteoarthropathy, spinal muscular atrophy, fragile X syndrome, Phelmn-McDerimid syndrome and intracranial cavernous hemangioma. The remaining five cases had complicated clinical manifestations, or disease development that could not be explained by the first diagnosed disease. Type IX collagen gene related disease, and neurofibromatosis type 1 were identified in case 6. Collagen VI-related myopathy with and osteogenesis imperfecta type XV was identified in case 7. Turner syndrome with chromosome karyotype of 45,X, and Segawa syndrome were identified in case 8. Chromosome 22q11.2 microduplication syndrome with a 2.64Mb microduplication, and autosomal dominant lower extremity-predominant spinal muscular atrophy-1 caused by <i>DYNC1H1</i> gene mutation were confirmed in case 9. KBG syndrome due to <i>ANKRD11</i> gene mutation, and neurodevelopmental disorder with regression, abnormal movement, language loss and epilepsy caused by <i>IRF2BPL</i> gene mutation were identified in case 10. We found between the two pathogenic genes, either or both of them were <i>de novo</i> mutations. The clinical manifestations of patients with double genetic diseases were complex and diverse. Whole exome sequencing of the core pedigree combining with a variety of molecular genetic tests would be helpful for accurate diagnosis, genetic counseling and individualized management. This study provides important information and basis for the diagnosis of patients with coexistence of double genetic diseases.

Prenatal Diagnosis of Chromosome 22q11.21 Microduplication Syndrome in a Fetus with Congenital Malformation of the Cardiovascular System: Case Report

A clinical case of microduplication of chromosome 22q11.21 in a fetus with a malformation of the cardiovascular system (vascular ring) is presented. This anatomical variant of the vascular ring is extremely rare and is formed by the pathological circumflex retroesophageal left-sided cervical aortic arch with the left arterial ductus arteriosus. The anatomical features of the circumflex cervical aortic arch are the left-sided pathological curved aortic arch in combination with the right-sided descending aorta. This vascular pathology can cause compression of the trachea and esophagus. This variant of the vascular ring is extremely unfavorable for surgical correction. Chromosome 22q11.21 microduplication syndrome is associated with the clinical presentation of “cat eye syndrome”. The clinical case description shows unique data from instrumental and genetic studies. All stages of examination of a pregnant woman from primary to tertiary medical care are described. The features and importance of a multidisciplinary approach are also presented.&#x0D; Every case of congenital heart defect in fetus, confirmed by echocardiographic method in a specialized institution, requires medical and genetic counseling. Using of the highly sensitive specific molecular cytogenetic method, comparative genomic hybridization, in prenatal diagnosis allows for timely diagnosis of microstructural disorders of chromosomes in fetus. Follow-up of a pregnant woman with congenital heart defect in the fetus requires a multidisciplinary approach not only to improve diagnosis and treatment, but also to calculate genetic risk.

A retrospective single-center analysis of prenatal diagnosis and follow-up of 626 chinese patients with positive non-invasive prenatal screening results.

This study explored the diagnostic efficiency of different prenatal diagnostic approaches for women with positive non-invasive prenatal screening (NIPS) results by analyzing their clinical information and pregnancy outcomes. We collected data on 626 NIPS-positive pregnant women from January 2017 to June 2021 and arranged subsequent prenatal diagnostic operations for them after genetic counseling, along with long-term intensive follow-up. A total of 567 women accepted invasive prenatal diagnosis (IPD) (90.58%), and 262 cases were confirmed as true positives for NIPS. The positive predictive values for trisomies 21 (T21), 18 (T18), and 13 (T13); sex chromosome aneuploidies (SCAs); rare autosomal trisomies (RATs); and microdeletion and microduplication syndromes (MMS) were 81.13%, 37.93%, 18.42%, 48.83%, 18.37%, and 41.67%, respectively. Discordant results between NIPS and IPD were observed in 48 cases, with the discordance rate being 8.47%. Additionally, there were 43 cases with discordant results between karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing. Additional reporting of RATs and MMS with routine NIPS that only detects T21/T18/T13 and SCAs can yield more accurate diagnoses. However, NIPS cannot be used as a substitute for IPD owing to its high false positive rate and discordance with other diagnostic methods. Therefore, we recommend CMA combined with karyotyping as the preferred method for accurately diagnosing NIPS-positive women.

Recurrent 17q12 microduplications contribute to renal disease but not diabetes

Background17q12 microdeletion and microduplication syndromes present as overlapping, multisystem disorders. We assessed the disease phenotypes of individuals with 17q12 CNV in a population-based cohort.MethodsWe investigated 17q12 CNV using microarray data...

Prenatal ultrasound phenotypic and genetic etiology of the 17q12 microduplication syndrome.

BackgroundSeveral studies have reported on the clinical phenotype of the 17q12 microduplication syndrome, a rare autosomal dominant genetic disorder, in children and adults, but few have reported on its prenatal diagnosis. This study analyzed the prenatal ultrasound phenotypes of the 17q12 microduplication syndrome to improve the understanding, diagnosis, and monitoring of this disease in fetuses.MethodsA retrospective analysis of 8,200 pregnant women who had received an invasive antenatal diagnosis at tertiary referral hospitals between January 2016 and August 2021 was performed. Amniotic fluid or cord blood was sampled from the pregnant women for karyotyping and chromosome microarray analysis (CMA).ResultsThe CMA revealed microduplication in the 17q12 region of the genome in five fetuses, involving fragments of about 1.5–1.9 Mb. Five fetuses with the 17q12 microduplication syndrome had different prenatal ultrasound phenotypes, including duodenal obstruction (two fetuses); mild ventriculomegaly, dysplasia of the septum pellucidum, agenesis of the corpus callosum (one fetus); and a strong echo in the left ventricle only (one fetus). The ultrasound phenotype of one fetus was normal. Among the five fetuses with the 17q12 microduplication syndrome, the parents of three refused CNV segregation analysis, while CNV segregation analysis was performed for the remaining two fetuses to confirm whether the disorder was inherited maternally or paternally, with normal phenotypes. After genetic counseling, the parents of those two fetuses chose to terminate the pregnancy, while the parents of the three unverified fetuses continued the pregnancy, with normal follow-up after birth.ConclusionAlthough prenatal ultrasound phenotypes in fetuses with the 17q12 microduplication syndrome are highly variable, our study has highlighted the distinct association between duodenal obstruction and the 17q12 microduplication syndrome. Understanding the relationship between the pathogenesis of the 17q12 microduplication in prenatal ultrasound phenotypes and its long-term prognosis will contribute to better genetic counseling concerning the 17q12 microduplication syndrome, which is still a challenge.

22q11 Copy Number Variations in a Brazilian Cohort of Children with Congenital Heart Disorders

Introduction: Congenital heart disease (CHD) is the most common type of congenital defect reported to be one of the leading causes of mortality in the first year of life. Microdeletion and microduplication syndromes (MMS) are associated with cardiac malformations. Understanding which genetic factors are involved in these conditions directly impacts treatment decisions. We aimed to identify the occurrence of genetic alterations and their association with MMS in CHD pediatric patients evaluated in a reference service of Southern Brazil. Methods: Participants were recruited during 2010 in the intensive care unit of a pediatric hospital. MMs and regions of chromosome 22 were screened by SALSA MLPA Probemix P245 Microdeletion Syndromes-1A kit for detection of copy number variations (CNVs). Results: MMS were detected in 11 from 207 patients (5.3%). Heterozygous deletion in the 22q11.2 chromosome region was the most prevalent CNV (5 from 11 patients). Also, atypical RTDR1 deletion and 22q11.2 duplication were detected. MLPA was able to reveal microdeletions in SNRPN and NF1 genes in patients with a normal karyotype and FISH. Conclusion: Our study reports the prevalence and variability of genomic alterations associated with MMS in CHD pediatric patients. The results by MLPA are of great help in planning and specialized care.

Phenotypic Overlap of 22q11.2 Microduplication and Noonan Syndrome in a Fetus with Increased NT, Facial Dysmorphism, and Narrow Pulmonary Trunk

Phenotypic Overlap of 22q11.2 Microduplication and Noonan Syndrome in a Fetus with Increased NT, Facial Dysmorphism, and Narrow Pulmonary Trunk

Novel findings, mini-review and dysmorphological characterization of 16p13.11 microduplication syndrome.

The short arm of chromosome 16 and especially the region 16p13.11 is a chromosome region where many structural variants, especially deletions and duplications, can be observed. Although deletions of this region are clinically well defined, duplications are rare, and so far, there is no established clinical consensus in regard with its clinical picture, and especially the dysmorphic perspective of the disease is far from being clear. A 5-year-and-2-month-old patient who presented with epilepsy, autism and late speech onset complaints was evaluated in our genetics department. On physical examination, unilateral preauricular skin tag and upslanting palpebral fissures were noted. Microarray analysis was performed and reported as ([hg19]: 16p13.11 (14.897.804-16.730.375) x3). The literature review revealed only a few reports about the syndrome, but some dysmorphological findings appear to recur in different reports, which enables a possible characterization. Dysmorphic findings were discussed.

Clinician views and experiences of non-invasive prenatal genetic screening tests in Australia.

Non-invasive prenatal screening (NIPS) is being increasingly used by expectant parents. Much provision of this test in Australia is occurring in clinical settings where specialised genetic counselling is unavailable, such as general practice. Potential psychosocial consequences from this kind of prenatal genetic screening remain largely unexplored. To explore clinicians' experiences with NIPS for aneuploidy, their perspectives of the benefits and harms of NIPS, clinicians' information needs, and their perceptions of the needs of expectant parents. Qualitative, semi-structured interviews with 17 health professionals (clinical geneticists, obstetricians, genetic counsellors and general practitioners) who request and counsel for NIPS in Australian hospital and private practice settings, conducted between June 2019 and February 2020. Five themes were identified relating to clinicians' perceptions and experiences of NIPS in their practice: perceived benefits of NIPS, perceived harms of NIPS (with two subthemes: clinical harms and psychosocial harms), financial and equity-related concerns, counselling as a protective buffer against perceived harms, and clinicians' unmet education needs. While clinicians view NIPS as a useful and high-quality screening test, especially for detection of common trisomies, many participants had concerns about how NIPS has been implemented in practice, particularly the quality (and often absence) of pre-/post-test counselling and the routinisation of testing for sex chromosome aneuploidies, microdeletion and microduplication syndromes. These findings support the need for targeted clinician training around NIPS, and for a shared decision-making approach to support expectant parents' autonomous decisions about NIPS.

Year-end academic review of 2021: Advances in the field of birth defect prevention and control in China as of 2021

Year-end academic review of 2021: Advances in the field of birth defect prevention and control in China as of 2021

Clinical application of expanded noninvasive prenatal testing for fetal chromosome abnormalities in a cohort of 39,580 pregnancies.

The aim of this study was to determine the predictive value of expanded noninvasive prenatal testing (NIPT-plus) for fetal chromosome abnormalities in the second trimester (12-26 weeks). We conducted a retrospective cohort study of 39,580 pregnancies with NIPT-plus. Screening positive cases were diagnosed with karyotyping and single-nucleotide polymorphism array analysis (SNP array)/copy number variation sequencing (CNV-seq) with follow-up. The positive predictive values (PPVs) of trisomy 21, 18, and 13 (T21, T18, and T13), sex chromosome aneuploidies (SCAs), and microdeletion and microduplication syndromes (MMS) by NIPT-plus were recorded. We assessed the predictive value of NIPT-plus based on maternal age and conventional indications. Of 39,580 pregnancies with NIPT-plus, 511 (1.3%) had prenatal screening positive results of fetal chromosome abnormality, of which 87.7% (448/511) had invasive prenatal diagnosis. NIPT-plus performed better in predicting fetal SCAs and chromosome aneuploidies for pregnancies with advanced maternal age (AMA) than young maternal age (YMA). Besides, the PPVs of T21, T13, and chromosome aneuploidies showed an upward trend when comparison was based on maternal age in 5-year subintervals. The termination rates of 45,X, 47,XXX, 47,XXY, and 47,XYY were 100% (11/11), 20.0% (3/15), 91.7% (22/24), and 7.1% (1/14) with postnatal follow-up. Last but not least, the PPV for MMS is 41.7% (30/72), which may have a positive correlation between the size of CNVs. Pregnant women with screen-positive results for common trisomies (T13, T18, and T21) were more willing to conduct invasive prenatal diagnosis compared to those with positive results for SCAs or MMS. However, the current study demonstrated SCAs and MMS had the lowest PPV. This highlights the importance of confirmatory prenatal diagnosis in those patients and the potential impact on genetic counseling and informative decision-making.

Analysis of autosomal dominant genes impacted by copy number loss in 24,844 fetuses without structural abnormalities

BackgroundThe broad application of high-resolution chromosome detection technology in prenatal diagnosis has identified copy number loss (CNL) involving autosomal dominant (AD) genes in certain fetuses. Exon sequencing of fetuses exhibiting structural anomalies yields diagnostic information in up to 20% of cases. However, there is currently no relevant literature about the genetic origin and pregnancy outcome of CNL involving AD genes in fetuses without structural abnormalities.ResultsThis was a prospective study involving pregnant women who underwent amniocentesis for fetal copy number variation sequencing (CNVseq). Detection of parent-of-origin was suggested in cases of samples with CNL involving AD genes and the pregnancy outcome was monitored. Amniotic fluid samples from 24,844 fetuses without structural abnormalities were successfully tested via CNVseq. The results showed that 134 fetuses (0.5%) had small CNL (< 10 Mb) containing AD genes, after excluding microdeletion and microduplication syndrome and polymorphisms. By monitoring the pregnancy outcomes of the 134 fetuses, we found that 104 (77.6%) were good, 13 (9.7%) were adverse, and 17 (12.7%) pregnant women voluntarily chose to terminate pregnancy. Of the 13 fetuses with adverse pregnancy outcomes, only 2 fetuses had phenotypes consistent with those of diseases caused by AD genes involved in CNL.ConclusionsThe overall prognosis for fetuses without family history or structural abnormalities but with small CNL containing AD genes detected during pregnancy is good. The genetic origin, overlap status of established haploinsufficient gene and/or region, size of the CNL, and genetic mode may affect the pathogenicity of the CNL.