scholarly journals Neurodevelopmental Disorders in Patients With Complex Phenotypes and Potential Complex Genetic Basis Involving Non-Coding Genes, and Double CNVs

2021 ◽  
Vol 12 ◽  
Author(s):  
Martina Servetti ◽  
Livia Pisciotta ◽  
Elisa Tassano ◽  
Maria Cerminara ◽  
Lino Nobili ◽  
...  
Keyword(s):  
Neurodevelopmental Disorders ◽  
Genetic Basis ◽  
De Novo ◽  
Diagnostic Yield ◽  
Genetic Diagnosis ◽  
Brain Diseases ◽  
Comparative Genomic ◽  
Incomplete Penetrance ◽  
Genetic Components ◽  
Complex Phenotypes

Neurodevelopmental disorders (NDDs) are a heterogeneous class of brain diseases, with a complex genetic basis estimated to account for up to 50% of cases. Nevertheless, genetic diagnostic yield is about 20%. Array-comparative genomic hybridization (array-CGH) is an established first-level diagnostic test able to detect pathogenic copy number variants (CNVs), however, most identified variants remain of uncertain significance (VUS). Failure of interpretation of VUSs may depend on various factors, including complexity of clinical phenotypes and inconsistency of genotype-phenotype correlations. Indeed, although most NDD-associated CNVs are de novo, transmission from unaffected parents to affected children of CNVs with high risk for NDDs has been observed. Moreover, variability of genetic components overlapped by CNVs, such as long non-coding genes, genomic regions with long-range effects, and additive effects of multiple CNVs can make CNV interpretation challenging. We report on 12 patients with complex phenotypes possibly explained by complex genetic mechanisms, including involvement of antisense genes and boundaries of topologically associating domains. Eight among the 12 patients carried two CNVs, either de novo or inherited, respectively, by each of their healthy parents, that could additively contribute to the patients’ phenotype. CNVs overlapped either known NDD-associated or novel candidate genes (PTPRD, BUD13, GLRA3, MIR4465, ABHD4, and WSCD2). Bioinformatic enrichment analyses showed that genes overlapped by the co-occurring CNVs have synergistic roles in biological processes fundamental in neurodevelopment. Double CNVs could concur in producing deleterious effects, according to a two-hit model, thus explaining the patients’ phenotypes and the incomplete penetrance, and variable expressivity, associated with the single variants. Overall, our findings could contribute to the knowledge on clinical and genetic diagnosis of complex forms of NDD.

scholarly journals Comparison of the diagnostic yield of aCGH and genome-wide sequencing across different neurodevelopmental disorders

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Francisco Martinez-Granero ◽  
Fiona Blanco-Kelly ◽  
Carolina Sanchez-Jimeno ◽  
Almudena Avila-Fernandez ◽  
Ana Arteche ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Neurodevelopmental Disorders ◽  
Diagnostic Yield ◽  
Genetic Diagnosis ◽  
Diagnostic Algorithm ◽  
Signs And Symptoms ◽  
Autism Spectrum ◽  
Global Developmental Delay ◽  
Comparative Genomic ◽  
Clinical Exome Sequencing

AbstractMost consensus recommendations for the genetic diagnosis of neurodevelopmental disorders (NDDs) do not include the use of next generation sequencing (NGS) and are still based on chromosomal microarrays, such as comparative genomic hybridization array (aCGH). This study compares the diagnostic yield obtained by aCGH and clinical exome sequencing in NDD globally and its spectrum of disorders. To that end, 1412 patients clinically diagnosed with NDDs and studied with aCGH were classified into phenotype categories: global developmental delay/intellectual disability (GDD/ID); autism spectrum disorder (ASD); and other NDDs. These categories were further subclassified based on the most frequent accompanying signs and symptoms into isolated forms, forms with epilepsy; forms with micro/macrocephaly and syndromic forms. Two hundred and forty-five patients of the 1412 were subjected to clinical exome sequencing. Diagnostic yield of aCGH and clinical exome sequencing, expressed as the number of solved cases, was compared for each phenotype category and subcategory. Clinical exome sequencing was superior than aCGH for all cases except for isolated ASD, with no additional cases solved by NGS. Globally, clinical exome sequencing solved 20% of cases (versus 5.7% by aCGH) and the diagnostic yield was highest for all forms of GDD/ID and lowest for Other NDDs (7.1% versus 1.4% by aCGH) and ASD (6.1% versus 3% by aCGH). In the majority of cases, diagnostic yield was higher in the phenotype subcategories than in the mother category. These results suggest that NGS could be used as a first-tier test in the diagnostic algorithm of all NDDs followed by aCGH when necessary.

Genetic diagnosis by comparative genomic hybridization in adult de novo acute myelocytic leukemia

2004 ◽  
Vol 153 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Sı́lvia Casas ◽  
Anna Aventı́n ◽  
Francisca Fuentes ◽  
Teresa Vallespı́ ◽  
Isabel Granada ◽  
...  
Keyword(s):  
Comparative Genomic Hybridization ◽  
De Novo ◽  
Genetic Diagnosis ◽  
Comparative Genomic ◽  
Acute Myelocytic Leukemia ◽  
Genomic Hybridization ◽  
Myelocytic Leukemia

scholarly journals P.109 Diagnostic Yield of Targeted Exome Sequencing in West Syndrome

2021 ◽  
Vol 48 (s3) ◽  
pp. S50-S50
Author(s):  
M Parfyonov ◽  
I Guella ◽  
DM Evans ◽  
S Adam ◽  
C DeGuzman ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Genetic Heterogeneity ◽  
High Throughput Sequencing ◽  
De Novo ◽  
Diagnostic Yield ◽  
Genetic Diagnosis ◽  
West Syndrome ◽  
Global Developmental Delay ◽  
Targeted Exome Sequencing ◽  
Ion Proton

Background: West syndrome (WS) is characterized by the onset of epileptic spasms usually within the first year of life. Global developmental delay with/without regression is common. Advances in high-throughput sequencing have supported the genetic heterogeneity of this condition. To better understand the genetic causes of this disorder, we investigated the results of targeted exome sequencing in 29 patients with WS. Methods: Whole exome sequencing (WES) was performed on an Ion ProtonTM and variant reporting was restricted to sequences of 620 known epilepsy genes. Diagnostic yield and treatment impact are described for 29 patients with WS. Results: A definitely/likely diagnosis was made in 10 patients (34%), which included 10 different genes (ALG13, PAFAH1B1, SLC35A2, DYNC1H1, ADSL, DEPDC5, ARX, CDKL5, SCN8A, STXBP1) known to be associated with epilepsy or WS. Most variants were de novo dominant (X-linked/autosomal) except for ARX (X-linked recessive) and ADSL (autosomal recessive). 4 out of 10 (40%) had a genetic diagnosis with potential treatment implications. Conclusions: These results emphasize the genetic heterogeneity of WS. The high diagnostic yield, along with the significant genetic variability, and the potential for treatment impact, supports the early use of this testing in patients with unexplained WS.

scholarly journals Two locus inheritance of non-syndromic midline craniosynostosis via rare SMAD6 and common BMP2 alleles

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Andrew T Timberlake ◽  
Jungmin Choi ◽  
Samir Zaidi ◽  
Qiongshi Lu ◽  
Carol Nelson-Williams ◽  
...  
Keyword(s):  
Epistatic Interaction ◽  
Osteoblast Differentiation ◽  
Genetic Basis ◽  
De Novo ◽  
Genetic Interaction ◽  
Cranial Sutures ◽  
Incomplete Penetrance ◽  
Common Variants ◽  
Neurologic Outcomes ◽  
Metopic Craniosynostosis

Premature fusion of the cranial sutures (craniosynostosis), affecting 1 in 2000 newborns, is treated surgically in infancy to prevent adverse neurologic outcomes. To identify mutations contributing to common non-syndromic midline (sagittal and metopic) craniosynostosis, we performed exome sequencing of 132 parent-offspring trios and 59 additional probands. Thirteen probands (7%) had damaging de novo or rare transmitted mutations in SMAD6, an inhibitor of BMP – induced osteoblast differentiation (p<10−20). SMAD6 mutations nonetheless showed striking incomplete penetrance (<60%). Genotypes of a common variant near BMP2 that is strongly associated with midline craniosynostosis explained nearly all the phenotypic variation in these kindreds, with highly significant evidence of genetic interaction between these loci via both association and analysis of linkage. This epistatic interaction of rare and common variants defines the most frequent cause of midline craniosynostosis and has implications for the genetic basis of other diseases.

scholarly journals Benefits of clinical criteria and high-throughput sequencing for diagnosing children with syndromic craniosynostosis

2020 ◽  
Author(s):  
Elin Tønne ◽  
Bernt Johan Due-Tønnessen ◽  
Inger-Lise Mero ◽  
Ulrikke Straume Wiig ◽  
Mari Ann Kulseth ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Sequencing ◽  
Diagnostic Yield ◽  
Single Gene ◽  
Genetic Diagnosis ◽  
Gene Analysis ◽  
Comparative Genomic ◽  
Genetic Syndromes ◽  
Clinical Criteria ◽  
Syndromic Craniosynostosis

AbstractAn accurate diagnosis of syndromic craniosynostosis (CS) is important for personalized treatment, surveillance, and genetic counselling. We describe detailed clinical criteria for syndromic CS and the distribution of genetic diagnoses within the cohort. The prospective registry of the Norwegian National Unit for Craniofacial Surgery was used to retrieve individuals with syndromic CS born between 1 January 2002 and 30 June 2019. All individuals were assessed by a clinical geneticist and classified using defined clinical criteria. A stepwise approach consisting of single-gene analysis, comparative genomic hybridization (aCGH), and exome-based high-throughput sequencing, first filtering for 72 genes associated with syndromic CS, followed by an extended trio-based panel of 1570 genes were offered to all syndromic CS cases. A total of 381 individuals were registered with CS, of whom 104 (27%) were clinically classified as syndromic CS. Using the single-gene analysis, aCGH, and custom-designed panel, a genetic diagnosis was confirmed in 73% of the individuals (n = 94). The diagnostic yield increased to 84% after adding the results from the extended trio-based panel. Common causes of syndromic CS were found in 53 individuals (56%), whereas 26 (28%) had other genetic syndromes, including 17 individuals with syndromes not commonly associated with CS. Only 15 individuals (16%) had negative genetic analyses. Using the defined combination of clinical criteria, we detected among the highest numbers of syndromic CS cases reported, confirmed by a high genetic diagnostic yield of 84%. The observed genetic heterogeneity encourages a broad genetic approach in diagnosing syndromic CS.

scholarly journals First Report of a de novo 10q23.31q23.33 Microdeletion: Obesity, Intellectual Disability and Microcephaly

2021 ◽  
pp. 1-5
Author(s):  
Ayberk Turkyilmaz ◽  
Erdal Kurnaz ◽  
Atilla Cayir
Keyword(s):  
Intellectual Disability ◽  
Array Cgh ◽  
De Novo ◽  
Chromosomal Abnormalities ◽  
Molecular Genetic ◽  
Genetic Diagnosis ◽  
Autism Spectrum ◽  
Comparative Genomic ◽  
Facial Dysmorphism ◽  
Genetic And Environmental Factors

Intellectual disability (ID) is characterized by limited or insufficient development of mental abilities, including intellectual functioning impairments, such as learning and understanding cause-effect relationships. Some cases have ID as the only finding and are called isolated cases. Conversely, cases accompanied by facial dysmorphism, microcephaly, autism spectrum disorder, epilepsy, obesity, and congenital anomalies are called syndromic developmental delay (DD)/ID. Isolated and syndromic DD/ID cases show extreme genetic heterogeneity. Genetic etiology can be detected in approximately 40% of the cases, whereas chromosomal abnormalities are observed in 25%. Obesity is a multifactorial disease in which both genetic and environmental factors play important roles. The role of heredity in obesity has been reported to be between 40 and 70%. Array-based comparative genomic hybridization (array-CGH) can detect CNVs in the whole genome at a higher resolution than conventional cytogenetic methods. Array-CGH is currently recommended as the first-tier genetic test for ID cases worldwide. In the present study, we aimed to evaluate clinical, radiological, and genetic analyses of a 12-year and 4-month-old girl with microcephaly, ID, and obesity. In the array-CGH analysis, a 3.1-Mb deletion, arr[GRGh37] 10q23.31g23.33 (92745793_95937944)×1 was detected, and this alteration was evaluated to be pathogenic. We consider that haploinsufficiency of the candidate genes (<i>GPR120</i>, <i>KIF11</i>, <i>EXOC6</i>, <i>CYP26A1</i>, <i>CYP26C1</i>, and <i>LGI1</i>) in the deletion region may explain microcephaly, ID, obesity, seizures, and ophthalmological findings in our patient. The investigation of 10q23.31q23.33 microdeletion in cases with syndromic obesity may contribute to molecular genetic diagnosis.

scholarly journals Duplication of chromosome 16p13.11-p12.3 with different expressions in the same family

2021 ◽  
Vol 24 (1) ◽  
pp. 89-94
Author(s):  
N Pop-Jordanova ◽  
T Zorcec ◽  
E Sukarova-Angelovska
Keyword(s):  
Neurodevelopmental Disorders ◽  
Gene Mutations ◽  
Autism Spectrum ◽  
Comparative Genomic ◽  
Incomplete Penetrance ◽  
Typical Development ◽  
Small Children ◽  
Neurodevelopmental Delay ◽  
Chromosomal Duplication ◽  
Older Siblings

Abstract The knowledge about genetic involvement in neurodevelopmental disorders, and especially in autism, is currently rising. To date, more than 100 gene mutations related to autistic syndromes have been described. Some disorders that affect multiple family members are caused by gene mutations, which can be inherited. Recently, array comparative genomic hybridization (aCGH) has identified sub microscopic deletions and duplications as a common cause of mental retardation and autism. In this article we report the occurrence of the same genetic finding (chromosome 16p13.11-p12.3 duplication) in a family with four small children, where two older siblings manifested a global neurodevelopmental delay associated with an autism spectrum disorder (ASD), but younger twin brothers with the same mutation, have typical development. Genetic analysis showed that the chromosomal duplication was inherited from the father, in which phenotype and functioning are quite typical. As is known, the duplication can pass from parents to children. The 16p13.11 micro duplication has been implicated in several neurodevelopmental and behavioral disorders and is characterized by variable expressivity and incomplete penetrance.

scholarly journals De novo Variants in Neurodevelopmental Disorders with Epilepsy

2017 ◽  
Author(s):  
Henrike O. Heyne ◽  
Tarjinder Singh ◽  
Hannah Stamberger ◽  
Rami Abou Jamra ◽  
Hande Caglayan ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Genetic Testing ◽  
Neurodevelopmental Disorders ◽  
Disease Gene ◽  
De Novo ◽  
Genetic Diagnosis ◽  
Disease Association ◽  
Joint Analysis ◽  
Limited Evidence ◽  
Significant Excess

AbstractEpilepsy is a frequent feature of neurodevelopmental disorders (NDD) but little is known about genetic differences between NDD with and without epilepsy. We analyzed de novo variants (DNV) in 6753 parent-offspring trios ascertained for different NDD. In the subset of 1942 individuals with NDD with epilepsy, we identified 33 genes with a significant excess of DNV, of which SNAP25 and GABRB2 had previously only limited evidence for disease association. Joint analysis of all individuals with NDD also implicated CACNA1E as a novel disease gene. Comparing NDD with and without epilepsy, we found missense DNV, DNV in specific genes, age of recruitment and severity of intellectual disability to be associated with epilepsy. We further demonstrate to what extent our results impact current genetic testing as well as treatment, emphasizing the benefit of accurate genetic diagnosis in NDD with epilepsy.

scholarly journals Population prevalence and inheritance pattern of recurrent CNVs associated with neurodevelopmental disorders in 12,252 newborns and their parents

2020 ◽  
Vol 29 (1) ◽  
pp. 205-215
Author(s):  
Dinka Smajlagić ◽  
Ksenia Lavrichenko ◽  
Siren Berland ◽  
Øyvind Helgeland ◽  
Gun Peggy Knudsen ◽  
...  
Keyword(s):  
Neurodevelopmental Disorders ◽  
De Novo ◽  
Copy Number Variations ◽  
Genetic Diagnostics ◽  
Incomplete Penetrance ◽  
Inheritance Pattern ◽  
Neurodevelopmental Delay ◽  
Population Prevalence ◽  
Total Prevalence ◽  
Genomic Regions

AbstractRecurrent copy number variations (CNVs) are common causes of neurodevelopmental disorders (NDDs) and associated with a range of psychiatric traits. These CNVs occur at defined genomic regions that are particularly prone to recurrent deletions and duplications and often exhibit variable expressivity and incomplete penetrance. Robust estimates of the population prevalence and inheritance pattern of recurrent CNVs associated with neurodevelopmental disorders (NDD CNVs) are lacking. Here we perform array-based CNV calling in 12,252 mother–father–child trios from the Norwegian Mother, Father, and Child Cohort Study (MoBa) and analyse the inheritance pattern of 26 recurrent NDD CNVs in 13 genomic regions. We estimate the total prevalence of recurrent NDD CNVs (duplications and deletions) in live-born children to 0.48% (95% C.I.: 0.37–0.62%), i.e., ~1 in 200 newborns has either a deletion or duplication in these NDDs associated regions. Approximately a third of the newborn recurrent NDD CNVs (34%, N = 20/59) are de novo variants. We provide prevalence estimates and inheritance information for each of the 26 NDD CNVs and find higher prevalence than previously reported for 1q21.1 deletions (~1:2000), 15q11.2 duplications (~1:4000), 15q13.3 microdeletions (~1:2500), 16p11.2 proximal microdeletions (~1:2000) and 17q12 deletions (~1:4000) and lower than previously reported prevalence for the 22q11.2 deletion (~1:12,000). In conclusion, our analysis of an unselected and representative population of newborns and their parents provides a clearer picture of the rate of recurrent microdeletions/duplications implicated in neurodevelopmental delay. These results will provide an important resource for genetic diagnostics and counseling.

scholarly journals Transcriptomic and genomic variants between koala populations reveals underlying genetic components to disorders in a bottlenecked population

2021 ◽  
Author(s):  
R. E. Tarlinton ◽  
J. Fabijan ◽  
F. Hemmatzadeh ◽  
J. Meers ◽  
H. Owen ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Genetic Disorders ◽  
South Australia ◽  
Differentially Expressed ◽  
Brain Diseases ◽  
Fixation Index ◽  
Testicular Development ◽  
Genetic Components ◽  
Anion Transporter ◽  
Two Populations

AbstractHistorical hunting pressures on koalas in the southern part of their range in Australia have led to a marked genetic bottleneck when compared with their northern counterparts. There are a range of suspected genetic disorders such as testicular abnormalities, oxalate nephrosis and microcephaly reported at higher prevalence in these genetically restricted southern animals. This paper reports analysis of differential expression of genes from RNAseq of lymph nodes, SNPs present in genes and the fixation index (population differentiation due to genetic structure) of these SNPs from two populations, one in south east Queensland, representative of the northern genotype and one in the Mount Lofty Ranges South Australia, representative of the southern genotype. SNPs that differ between these two populations were significantly enriched in genes associated with brain diseases. Genes which were differentially expressed between the two populations included many associated with brain development or disease, and in addition a number associated with testicular development, including the androgen receptor. Finally, one of the 8 genes both differentially expressed and with a statistical difference in SNP frequency between populations was SLC26A6 (solute carrier family 26 member 6), an anion transporter that was upregulated in SA koalas and is associated with oxalate transport and calcium oxalate uroliths in humans. Together the differences in SNPs and gene expression described in this paper suggest an underlying genetic basis for several disorders commonly seen in southern Australian koalas, supporting the need for further research into the genetic basis of these conditions, and highlighting that genetic selection in managed populations may need to be considered in the future.

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