The p. Thr395Met missense variant of NFIA found in a patient with intellectual disability is a defective variant

Abstract Background De novo pathogenic variants in the DDX3X gene are reported to account for 1–3% of unexplained intellectual disability (ID) in females, leading to the rare disease known as DDX3X syndrome (MRXSSB, OMIM #300958). Besides ID, these patients manifest a variable clinical presentation, which includes neurological and behavioral defects, and abnormal brain MRIs. Case presentation We report a 10-year-old girl affected by delayed psychomotor development, delayed myelination, and polymicrogyria (PMG). We identified a novel de novo missense mutation in the DDX3X gene (c.625C > G) by whole exome sequencing (WES). The DDX3X gene encodes a DEAD-box ATP-dependent RNA-helicase broadly implicated in gene expression through regulation of mRNA metabolism. The identified mutation is located just upstream the helicase domain and is suggested to impair the protein activity, thus resulting in the altered translation of DDX3X-dependent mRNAs. The proband, presenting with the typical PMG phenotype related to the syndrome, does not show other clinical signs frequently reported in presence of missense DDX3X mutations that are associated with a most severe clinical presentation. In addition, she has brachycephaly, never described in female DDX3X patients, and macroglossia, that has never been associated with the syndrome. Conclusions This case expands the knowledge of DDX3X pathogenic variants and the associated DDX3X syndrome phenotypic spectrum.

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The Diagnostic Journey of a Patient with Prader–Willi-Like Syndrome and a Unique Homozygous SNURF-SNRPN Variant; Bio-Molecular Analysis and Review of the Literature

Genes ◽

10.3390/genes12060875 ◽

2021 ◽

Vol 12 (6) ◽

pp. 875

Author(s):

Karlijn Pellikaan ◽

Geeske M. van Woerden ◽

Lotte Kleinendorst ◽

Anna G. W. Rosenberg ◽

Bernhard Horsthemke ◽

...

Keyword(s):

Intellectual Disability ◽

Single Nucleotide Polymorphism Array ◽

Genetic Defect ◽

Missense Variant ◽

Dominant Negative ◽

Dominant Negative Effect ◽

Pituitary Hormone ◽

Negative Effect

Prader–Willi syndrome (PWS) is a rare genetic condition characterized by hypotonia, intellectual disability, and hypothalamic dysfunction, causing pituitary hormone deficiencies and hyperphagia, ultimately leading to obesity. PWS is most often caused by the loss of expression of a cluster of genes on chromosome 15q11.2-13. Patients with Prader–Willi-like syndrome (PWLS) display features of the PWS phenotype without a classical PWS genetic defect. We describe a 46-year-old patient with PWLS, including hypotonia, intellectual disability, hyperphagia, and pituitary hormone deficiencies. Routine genetic tests for PWS were normal, but a homozygous missense variant NM_003097.3(SNRPN):c.193C>T, p.(Arg65Trp) was identified. Single nucleotide polymorphism array showed several large regions of homozygosity, caused by high-grade consanguinity between the parents. Our functional analysis, the ‘Pipeline for Rapid in silico, in vivo, in vitro Screening of Mutations’ (PRiSM) screen, showed that overexpression of SNRPN-p.Arg65Trp had a dominant negative effect, strongly suggesting pathogenicity. However, it could not be confirmed that the variant was responsible for the phenotype of the patient. In conclusion, we present a unique homozygous missense variant in SNURF-SNRPN in a patient with PWLS. We describe the diagnostic trajectory of this patient and the possible contributors to her phenotype in light of the current literature on the genotype–phenotype relationship in PWS.

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A recurrent missense variant inSLC9A7causes nonsyndromic X-linked intellectual disability with alteration of Golgi acidification and aberrant glycosylation

Human Molecular Genetics ◽

10.1093/hmg/ddy371 ◽

2018 ◽

Vol 28 (4) ◽

pp. 598-614 ◽

Cited By ~ 11

Author(s):

Wujood Khayat ◽

Anna Hackett ◽

Marie Shaw ◽

Alina Ilie ◽

Tracy Dudding-Byth ◽

...

Keyword(s):

Intellectual Disability ◽

Missense Variant ◽

Aberrant Glycosylation

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Recurrent de novo missense variants in GNB2 can cause syndromic intellectual disability

Journal of Medical Genetics ◽

10.1136/jmedgenet-2020-107462 ◽

2021 ◽

pp. jmedgenet-2020-107462

Author(s):

Natalie B Tan ◽

Alistair T Pagnamenta ◽

Matteo P Ferla ◽

Jonathan Gadian ◽

Brian HY Chung ◽

...

Keyword(s):

Intellectual Disability ◽

G Proteins ◽

De Novo ◽

Neurodevelopmental Disorder ◽

Missense Variant ◽

Cellular Functions ◽

Missense Variants ◽

Neurodevelopmental Disease ◽

Genes Encoding ◽

International Data

PurposeBinding proteins (G-proteins) mediate signalling pathways involved in diverse cellular functions and comprise Gα and Gβγ units. Human diseases have been reported for all five Gβ proteins. A de novo missense variant in GNB2 was recently reported in one individual with developmental delay/intellectual disability (DD/ID) and dysmorphism. We aim to confirm GNB2 as a neurodevelopmental disease gene, and elucidate the GNB2-associated neurodevelopmental phenotype in a patient cohort.MethodsWe discovered a GNB2 variant in the index case via exome sequencing and sought individuals with GNB2 variants via international data-sharing initiatives. In silico modelling of the variants was assessed, along with multiple lines of evidence in keeping with American College of Medical Genetics and Genomics guidelines for interpretation of sequence variants.ResultsWe identified 12 unrelated individuals with five de novo missense variants in GNB2, four of which are recurrent: p.(Ala73Thr), p.(Gly77Arg), p.(Lys89Glu) and p.(Lys89Thr). All individuals have DD/ID with variable dysmorphism and extraneurologic features. The variants are located at the universally conserved shared interface with the Gα subunit, which modelling suggests weaken this interaction.ConclusionMissense variants in GNB2 cause a congenital neurodevelopmental disorder with variable syndromic features, broadening the spectrum of multisystem phenotypes associated with variants in genes encoding G-proteins.

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A missense variant, p.(Ile269Asn), in MC4R as a secondary finding in a child with BCL11A-related intellectual disability

European Journal of Medical Genetics ◽

10.1016/j.ejmg.2020.103969 ◽

2020 ◽

Vol 63 (9) ◽

pp. 103969

Author(s):

Daniah T. Beleford ◽

Jessica Van Ziffle ◽

Ugur Hodoglugil ◽

Anne M. Slavotinek

Keyword(s):

Intellectual Disability ◽

Missense Variant ◽

Secondary Finding

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Novel homozygous variant in the TPO gene associated with congenital hypothyroidism and mild-intellectual disability

Human Genome Variation ◽

10.1038/s41439-020-00129-3 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Amjad Khan ◽

Muhammad Umair ◽

Rania Abdulfattah Sharaf ◽

Muhammad Ismail Khan ◽

Amir Ullah ◽

...

Keyword(s):

Intellectual Disability ◽

Congenital Hypothyroidism ◽

Autosomal Recessive ◽

Missense Variant ◽

Thyroid Peroxidase ◽

Mild Intellectual Disability ◽

Complex Disorder ◽

Whole Exome ◽

Hereditary Disorders ◽

Autosomal Recessive Manner

AbstractCongenital hypothyroidism (CH) is one of the most common hereditary disorders affecting neonates worldwide. CH is a multifactorial complex disorder and can be caused by either environmental factors or genetic factors. We studied one Pakistani family with segregating mutations in CH inherited in an autosomal recessive manner. Using whole-exome sequencing (WES), we found a novel homozygous missense variant (c.2315A>G; p.Tyr772Cys) in the thyroid peroxidase (TPO) gene. Different bioinformatics prediction tools and Sanger sequencing were performed to verify the identified variant. Our findings highlight the importance of this gene in causing CH and mild-intellectual disability (ID) in two affected brothers. WES is a convenient and useful tool for the clinical diagnosis of CH and other associated disorders.

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Association of the missense variant p.Arg203Trp in PACS1 as a cause of intellectual disability and seizures

Clinical Genetics ◽

10.1111/cge.12956 ◽

2017 ◽

Vol 92 (2) ◽

pp. 221-223 ◽

Cited By ~ 7

Author(s):

D. Stern ◽

M.T. Cho ◽

R. Chikarmane ◽

R. Willaert ◽

K. Retterer ◽

...

Keyword(s):

Intellectual Disability ◽

Missense Variant

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OTUD5 Variants Associated With X-Linked Intellectual Disability and Congenital Malformation

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.631428 ◽

2021 ◽

Vol 9 ◽

Author(s):

Ken Saida ◽

Tokiko Fukuda ◽

Daryl A. Scott ◽

Toru Sengoku ◽

Kazuhiro Ogata ◽

...

Keyword(s):

Intellectual Disability ◽

Developmental Delay ◽

Ovarian Tumor ◽

Brain Magnetic Resonance Imaging ◽

Missense Variant ◽

The Novel ◽

Nasal Bridge ◽

Congenital Cardiac Anomalies ◽

Novel Variant ◽

Long Term Prognosis

BackgroundX-linked intellectual disability (XLID), which occurs predominantly in males, is a relatively common and genetically heterogeneous disorder in which over 100 mutated genes have been reported. The OTUD5 gene at Xp11.23 encodes ovarian tumor deubiquitinase 5 protein, which is a deubiquitinating enzyme member of the ovarian tumor family. LINKage-specific-deubiquitylation-deficiency-induced embryonic defects (LINKED) syndrome, arising from pathogenic OTUD5 variants, was recently reported as a new XLID with additional congenital anomalies.MethodsWe investigated three affected males (49- and 47-year-old brothers [Individuals 1 and 2] and a 2-year-old boy [Individual 3]) from two families who showed developmental delay. Their common clinical features included developmental delay, hypotonia, short stature, and distinctive facial features, such as telecanthus and a depressed nasal bridge. Individuals 1 and 2 showed epilepsy and brain magnetic resonance imaging showed a thin corpus callosum and mild ventriculomegaly. Individual 3 showed congenital malformations, including tetralogy of Fallot, hypospadias, and bilateral cryptorchidism. To identify the genetic cause of these features, we performed whole-exome sequencing.ResultsA hemizygous OTUD5 missense variant, c.878A>T, p.Asn293Ile [NM_017602.4], was identified in one family with Individuals 1 and 2, and another missense variant, c.1210 C>T, p.Arg404Trp, in the other family with Individual 3, respectively. The former variant has not been registered in public databases and was predicted to be pathogenic by multiple in silico prediction tools. The latter variant p.Arg404Trp was previously reported as a pathogenic OTUD5 variant, and Individual 3 showed a typical LINKED syndrome phenotype. However, Individuals 1 and 2, with the novel variant (p.Asn293Ile), showed no cardiac or genitourinary malformations.ConclusionsUnlike previous reports of LINKED syndrome, which described early lethality with congenital cardiac anomalies, our three cases are still alive. Notably, the adult brothers with the novel missense OTUD5 variant have lived into their forties. This may be indicative of a milder phenotype as a possible genotype-phenotype correlation. These findings imply a possible long-term prognosis for individuals with this new XLID syndrome, and a wider phenotypic variation than initially thought.

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