Prominent and Regressive Brain Developmental Disorders Associated with Nance-Horan Syndrome

Nance-Horan syndrome (NHS) is a rare X-linked developmental disorder caused mainly by loss of function variants in the NHS gene. NHS is characterized by congenital cataracts, dental anomalies, and distinctive facial features, and a proportion of the affected individuals also present intellectual disability and congenital cardiopathies. Despite identification of at least 40 distinct hemizygous variants leading to NHS, genotype-phenotype correlations remain largely elusive. In this study, we describe a Sicilian family affected with congenital cataracts and dental anomalies and diagnosed with NHS by whole-exome sequencing (WES). The affected boy from this family presented a late regression of cognitive, motor, language, and adaptive skills, as well as broad behavioral anomalies. Furthermore, brain imaging showed corpus callosum anomalies and periventricular leukoencephalopathy. We expand the phenotypic and mutational NHS spectrum and review potential disease mechanisms underlying the central neurological anomalies and the potential neurodevelopmental features associated with NHS.

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Novel variants identified in CKAP2L in two siblings with Filippi Syndrome

Molecular Case Studies ◽

10.1101/mcs.a006130 ◽

2021 ◽

pp. mcs.a006130

Author(s):

Ryan J Patrick ◽

Jill M Weimer ◽

Laura Davis-Keppen ◽

Megan L Landsverk

Keyword(s):

Intellectual Disability ◽

Autosomal Recessive ◽

Missense Variant ◽

Facial Features ◽

Loss Of Function ◽

Pathogenic Variants ◽

Whole Exome ◽

The Family ◽

Novel Variants ◽

In Trans

Pathogenic variants in CKAP2L have previously been reported in Filippi Syndrome (FS), a rare autosomal recessive, craniodigital syndrome characterized by microcephaly, syndactyly, short stature, intellectual disability, and dysmorphic facial features. To date, fewer than ten patients with pathogenic variants in CKAP2L associated with FS have been reported. All of the previously reported probands have presumed loss-of-function variants (frameshift, canonical splice site, starting methionine) and all but one have been homozygous for a pathogenic variant. Here we describe two brothers who presented with microcephaly, micrognathia, syndactyly, dysmorphic features, and intellectual disability. Whole exome sequencing of the family identified a missense variant, c.2066G>A (p.Arg689His), in trans with a frameshift variant, c.1169_1173del (p.Ile390LysfsTer4), in CKAP2L. To our knowledge, these are the first patients with FS to be reported with a missense variant in CKAP2L and only the second family to be reported with two variants in trans.

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A de novo variant in CASK gene causing intellectual disability and brain hypoplasia: A Case Report and Literature Review

10.21203/rs.3.rs-317232/v1 ◽

2021 ◽

Author(s):

Ying Zhang ◽

Yanyan Nie ◽

Yu Mu ◽

Jie Zheng ◽

Xiaowei Xu ◽

...

Keyword(s):

Intellectual Disability ◽

Mental Disorders ◽

De Novo ◽

Clinical Symptoms ◽

Clinical Manifestations ◽

De Novo Mutation ◽

Loss Of Function ◽

Bioinformatics Analyses ◽

Whole Exome ◽

De Novo Variant

Abstract Background：The pathogenic variation of CASK gene can cause CASK related mental disorders. The main clinical manifestations are microcephaly with pontine and cerebellar hypoplasia, X-linked mental disorders with or without nystagmus and FG syndrome. The main pathogenic mechanism is the loss of function of related protein caused by mutation. We reported a Chinese male newborn with a de novo variant in CASK gene. Case presentation：We present an 18-day-old baby with intellectual disability and brain hypoplasia. Whole-exome sequencing was performed, which detected a hemizygous missense mutation c.764G>A of CASK gene. The mutation changed the 255th amino acid from Arg to His. Software based bioinformatics analyses were conducted to infer its functional effect.Conclusions：In this paper, a de novo mutation of CASK gene was reported. Moreover, a detailed description of all the cases described in the literature is reported.CASK mutations cause a variety of clinical phenotypes. Its diagnosis is difficult due to the lack of typical clinical symptoms. Genetic testing should be performed as early as possible if this disease is suspected. This case provides an important reference for the diagnosis and treatment of future cases.

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The First Case Report of Kabuki Syndrome from the National Iranian Registry of Primary Immunodeficiencies

Endocrine Metabolic & Immune Disorders - Drug Targets ◽

10.2174/1871530321666210114153920 ◽

2021 ◽

Vol 21 ◽

Author(s):

Molood Safarirad ◽

Ali Abbaszadeh Ganji ◽

Saba Fekrvand ◽

Reza Yazdani ◽

Ahmad Vosughi Motlagh ◽

...

Keyword(s):

Congenital Anomaly ◽

Intellectual Disability ◽

Definitive Diagnosis ◽

Facial Features ◽

Kabuki Syndrome ◽

Rare Congenital Anomaly ◽

Dysmorphic Features ◽

Pathogenic Variants ◽

First Case ◽

Whole Exome

: Kabuki syndrome is a rare congenital anomaly/mental retardation syndrome characterized by intellectual disability, developmental delay, short stature, facial dysmorphic features including ectropion of the lateral third of the lower eyelids and long palpebral fissures, and prominent finger pads. Pathogenic variants of KMT2D (MLL2) and KDM6A are found to be the major causes of Kabuki syndrome. Here, we report the first Iranian case with Kabuki syndrome with an IQ of 79, two episodes of viral pneumonia and distinctive facial features, prominent ears and persistent fetal fingertip pads. These characteristics raised our suspicion for performing whole-exome sequencing (WES), which revealed 2 heterozygous pathogenic missense variants in the KMT2D gene: c.C10024T in exon 34 leading to p.R3342C and c.G15005A in exon 48 leading to p.R5002Q. Hence, the definitive diagnosis of Kabuki syndrome was made based on molecular findings along with the intellectual disability and characteristic facial features.

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Fetal Anomalies Associated with Novel Pathogenic Variants in TMEM94

Genes ◽

10.3390/genes11090967 ◽

2020 ◽

Vol 11 (9) ◽

pp. 967

Author(s):

Mohamed H. Al-Hamed ◽

Nada Alsahan ◽

Maha Tulbah ◽

Wesam Kurdi ◽

Wafa’a I. Ali ◽

...

Keyword(s):

Developmental Disorder ◽

Chromosomal Microarray ◽

Global Developmental Delay ◽

Facial Features ◽

Chromosomal Microarray Analysis ◽

Speech Delay ◽

Loss Of Function ◽

Pathogenic Variants ◽

Antenatal Sonography ◽

First Time

Background: Intellectual developmental disorder with cardiac defects and dysmorphic facies (IDDCDF, MIM 618316) is a newly described disorder. It is characterized by global developmental delay, intellectual disability and speech delay, congenital cardiac malformations, and dysmorphic facial features. Biallelic pathogenic variants of TMEM94 are associated with IDDCDF. Methods and Results: In a prenatal setting, where fetal abnormalities were detected using antenatal sonography, we used trio-exome sequencing (trio-ES) in conjunction with chromosomal microarray analysis (CMA) to identify two novel homozygous loss of function variants in the TMEM94 gene (c.606dupG and c.2729-2A>G) in two unrelated Saudi Arabian families. Conclusions: This study provides confirmation that TMEM94 variants may cause IDDCDF. For the first time we describe the pathogenicity of TMEM94 defects detected during the prenatal period.

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A Novel Multi-Exon Deletion of PACS1 in a Three-Generation Pedigree: Supplements to PACS1 Neurodevelopmental Disorder Spectrum

Frontiers in Genetics ◽

10.3389/fgene.2021.690216 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yuan Liu ◽

Hongke Ding ◽

Tizhen Yan ◽

Ling Liu ◽

Lihua Yu ◽

...

Keyword(s):

Neurodevelopmental Disorder ◽

Dominant Negative ◽

Facial Features ◽

Missense Mutations ◽

Loss Of Function ◽

Pathogenic Variants ◽

Cognitive Delay ◽

Whole Exome ◽

Before And After ◽

Exon Deletion

PACS1 neurodevelopmental disorder (PACS1-NDD) is a category of rare disorder characterized by intellectual disability, speech delay, dysmorphic facial features, and developmental delay. Other various physical abnormalities of PACS1-NDD might involve all organs and systems. Notably, there were only two unique missense mutations [c.607C > T (p.Arg203Trp) and c.608G > A (p.Arg203Gln)] in PACS1 that had been identified as pathogenic variants for PACS1-NDD or Schuurs-Hoeijmakers syndrome (SHMS). Previous reports suggested that these common missense variants were likely to act through dominant-negative or gain-of-function effects manner. It is still uncertain whether the intragenic deletion or duplication in PACS1 will be disease-causing. By using whole-exome sequencing, we first identified a novel heterozygous multi-exon deletion covering exons 12–24 in PACS1 (NM_018026) in four individuals (two brothers and their father and grandfather) in a three-generation family. The younger brother was referred to our center prenatally and was evaluated before and after the birth. Unlike SHMS, no typical dysmorphic facial features, intellectual problems, and structural brain anomalies were observed among these four individuals. The brothers showed a mild hypermyotonia of their extremities at the age of 3 months old and recovered over time. Mild speech and cognitive delay were also noticed in the two brothers at the age of 13 and 27 months old, respectively. However, their father and grandfather showed normal language and cognitive competence. This study might supplement the spectrum of PACS1-NDD and demonstrates that the loss of function variation in PACS1 displays no contributions to the typical SHMS which is caused by the recurrent c.607C > T (p.Arg203Trp) variant.

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Mapping Autosomal Recessive Intellectual Disability: Combined Microarray and Exome Sequencing Identifies 26 Novel Candidate Genes in 192 Consanguineous Families

10.1101/092346 ◽

2016 ◽

Author(s):

Ricardo Harripaul ◽

Nasim Vasli ◽

Anna Mikhailov ◽

Muhammad Arshad Rafiq ◽

Kirti Mittal ◽

...

Keyword(s):

Intellectual Disability ◽

Exome Sequencing ◽

Autosomal Recessive ◽

De Novo ◽

Clinical Diagnostics ◽

High Yield ◽

Disease Genes ◽

Missense Mutations ◽

Loss Of Function ◽

Whole Exome

Approximately 1% of the global population is affected by intellectual disability (ID), and the majority receive no molecular diagnosis. Previous studies have indicated high levels of genetic heterogeneity, with estimates of more than 2500 autosomal ID genes, the majority of which are autosomal recessive (AR). Here, we combined microarray genotyping, homozygosity-by-descent (HBD) mapping, copy number variation (CNV) analysis, and whole exome sequencing (WES) to identify disease genes/mutations in 192 multiplex Pakistani and Iranian consanguineous families with non-syndromic ID. We identified definite or candidate mutations (or CNVs) in 51% of families in 72 different genes, including 26 not previously reported for ARID. The new ARID genes include nine with loss-of-function mutations(ABI2, MAPK8, MPDZ, PIDD1, SLAIN1, TBC1D23, TRAPPC6B, UBA7,andUSP44),and missense mutations include the first reports of variants inBDNForTET1associated with ID. The genes identified also showed overlap withde novogene sets for other neuropsychiatric disorders. Transcriptional studies showed prominent expression in the prenatal brain. The high yield of AR mutations for ID indicated that this approach has excellent clinical potential and should inform clinical diagnostics, including clinical whole exome and genome sequencing, for populations in which consanguinity is common. As with other AR disorders, the relevance will also apply to outbred populations.

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Intellectual disability and microcephaly associated with a novel CHAMP1 mutation

Human Genome Variation ◽

10.1038/s41439-021-00165-7 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Yuta Asakura ◽

Hitoshi Osaka ◽

Hiromi Aoi ◽

Takeshi Mizuguchi ◽

Naomichi Matsumoto ◽

...

Keyword(s):

Differential Diagnosis ◽

Intellectual Disability ◽

Nonsense Mutation ◽

Developmental Disorders ◽

Developmental Disorder ◽

Global Developmental Delay ◽

Chromosomal Segregation ◽

Chromosome Alignment ◽

Number Of Genes ◽

Old Japanese

AbstractMutations in a number of genes related to chromosomal segregation reportedly cause developmental disorders, e.g., chromosome alignment-maintaining phosphoprotein 1 (CHAMP1). We report on an 8-year-old Japanese girl who presented with a developmental disorder and microcephaly and carries a novel nonsense mutation in CHAMP1. Therefore, CHAMP1 mutation should be considered as a differential diagnosis of global developmental delay and microcephaly.

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Novel Mutation in LARP7 in Two Iranian Consanguineous Families with Syndromic Intellectual Disability and Facial Dysmorphism

Archives of Iranian Medicine ◽

10.34172/aim.2020.112 ◽

2020 ◽

Vol 23 (12) ◽

pp. 842-847

Author(s):

Goli Kazemi ◽

Fatemeh Peymani ◽

Marzieh Mohseni ◽

Farzane Zare Ashrafi ◽

Sanaz Arzhangi ◽

...

Keyword(s):

Intellectual Disability ◽

Neurodevelopmental Disorders ◽

Novel Mutation ◽

Facial Dysmorphism ◽

Loss Of Function ◽

Disease Mechanism ◽

Acceptor Splice Site ◽

Whole Exome ◽

Genetic Landscape ◽

Iranian Patients

Background: Recently, we have reported mutations in LARP7 gene, leading to neurodevelopmental disorders (NDDs), the most frequent cause of disability in children with a broad phenotype spectrum and diverse genetic landscape. Methods: Here, we present two Iranian patients from consanguineous families with syndromic intellectual disability, facial dysmorphism, and short stature. Results: Whole-exome sequencing (WES) revealed a novel homozygous stop-gain (c.C925T, p.R309X) variant and a previously known homozygous acceptor splice-site (c.1669-1_1671del) variant in LARP7 gene, indicating the diagnosis of Alazami syndrome. Conclusion: These identified variants in patients with Alazami syndrome were consistent with previously reported loss of function variants in LARP7 and provide further evidence that loss of function of LARP7 is the disease mechanism.

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Non-coding variants upstream of MEF2C cause severe developmental disorder through three distinct loss-of-function mechanisms

10.1101/2020.11.15.20229807 ◽

2020 ◽

Author(s):

Caroline F Wright ◽

Nicholas M Quaife ◽

Laura Ramos-Hernández ◽

Petr Danecek ◽

Matteo P Ferla ◽

...

Keyword(s):

Developmental Disorders ◽

Developmental Disorder ◽

De Novo ◽

Diagnostic Yield ◽

Severe Disease ◽

Loss Of Function ◽

Single Nucleotide Variants ◽

Clinical Genetic ◽

Protein Coding ◽

Coding Variants

AbstractClinical genetic testing of protein-coding regions identifies a likely causative variant in only ∼35% of severe developmental disorder (DD) cases. We screened 9,858 patients from the Deciphering Developmental Disorders (DDD) study for de novo mutations in the 5’untranslated regions (5’UTRs) of dominant haploinsufficient DD genes. We identify four single nucleotide variants and two copy number variants upstream of MEF2C that cause DD through three distinct loss-of-function mechanisms, disrupting transcription, translation, and/or protein function. These non-coding variants represent 23% of disease-causing variants identified in MEF2C in the DDD cohort. Our analyses show that non-coding variants upstream of known disease-causing genes are an important cause of severe disease and demonstrate that analysing 5’UTRs can increase diagnostic yield, even using existing exome sequencing datasets. We also show how non-coding variants can help inform both the disease-causing mechanism underlying protein-coding variants, and dosage tolerance of the gene.

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Phenotypic and molecular spectra of patients with switch/sucrose nonfermenting complex-related intellectual disability disorders in Korea

BMC Medical Genomics ◽

10.1186/s12920-021-01104-9 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Yena Lee ◽

Yunha Choi ◽

Go Hun Seo ◽

Gu-Hwan Kim ◽

Changwon Keum ◽

...

Keyword(s):

Intellectual Disability ◽

Developmental Disorders ◽

Molecular Spectra ◽

Speech Delay ◽

Dna Accessibility ◽

Pathogenic Variants ◽

Disease Spectrum ◽

Chromatin Remodeling Complex ◽

Whole Exome ◽

Altered Gene

Abstract Background The switch/sucrose nonfermenting (SWI/SNF) complex is an adenosine triphosphate-dependent chromatin-remodeling complex associated with the regulation of DNA accessibility. Germline mutations in the components of the SWI/SNF complex are related to human developmental disorders, including the Coffin–Siris syndrome (CSS), Nicolaides–Baraitser syndrome (NCBRS), and nonsyndromic intellectual disability. These disorders are collectively referred to as SWI/SNF complex-related intellectual disability disorders (SSRIDDs). Methods Whole-exome sequencing was performed in 564 Korean patients with neurodevelopmental disorders. Twelve patients with SSRIDDs (2.1%) were identified and their medical records were retrospectively analyzed. Results ARID1B, found in eight patients, was the most frequently altered gene. Four patients harbored pathogenic variants in SMARCA4, SMARCB1, ARID2, and SMARCA2. Ten patients were diagnosed with CSS, and one patient without a typical phenotype was diagnosed with ARID1B-related nonsyndromic intellectual disability. Another patient harboring the SMARCA2 pathogenic variant was diagnosed with NCBRS. All pathogenic variants in ARID1B were truncating, whereas variants in SMARCA2, SMARCB1, and SMARCA4 were nontruncating (missense). Frequently observed phenotypes were thick eyebrows (10/12), hypertrichosis (8/12), coarse face (8/12), thick lips (8/12), and long eyelashes (8/12). Developmental delay was observed in all patients, and profound speech delay was also characteristic. Agenesis or hypoplasia of the corpus callosum was observed in half of the patients (6/12). Conclusions SSRIDDs have a broad disease spectrum, including NCBRS, CSS, and ARID1B-related nonsyndromic intellectual disability. Thus, SSRIDDs should be considered as a small but important cause of human developmental disorders.

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