Marshall-Smith Research Articles

NFIX gene mutation causes Marshall-Smith syndrome in a pair of identical twins and literature review

This article reports on the clinical and genetic characteristics of monozygotic twins with Marshall-Smith syndrome (MRSHSS) due to a mutation in the NFIX gene, along with a review of related literature. Both patients presented with global developmental delays, a prominent forehead, shallow eye sockets, and pectus excavatum. Genetic testing revealed a heterozygous splicing site mutation c.697+1G>A in both children, with parents showing wild-type at this locus. According to the guidelines of the American College of Medical Genetics and Genomics, this mutation is considered likely pathogenic and has not been previously reported in the literature. A review of the literature identified 32 MRSHSS patients with splicing/frameshift mutations. Accelerated bone maturation and moderate to severe global developmental delay/intellectual disability are the primary clinical manifestations of patients with MRSHSS. Genetic testing results are crucial for the diagnosis of this condition.

Identification of cellular retinoic acid binding protein 2 (CRABP2) as downstream target of nuclear factor I/X (NFIX): implications for skeletal dysplasia syndromes.

Nuclear factor I/X (NFIX) mutations are associated with 2 skeletal dysplasias, Marshall-Smith (MSS) and Malan (MAL) syndromes. NFIX encodes a transcription factor that regulates expression of genes, including Bobby sox (BBX) and glial fibrillary acidic protein (GFAP) in neural progenitor cells and astrocytes, respectively. To elucidate the role of NFIX mutations in MSS, we studied their effects in fibroblast cell lines obtained from 5 MSS unrelated patients and 3 unaffected individuals. The 5 MSS NFIX frameshift mutations in exons 6-8 comprised 3 deletions (c.819-732_1079-948del, c.819-471_1079-687del, c.819-592_1079-808del), an insertion (c.1037_1038insT), and a duplication (c.1090dupG). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot analyses using MSS and unrelated control fibroblasts and in vitro expression studies in monkey kidney fibroblast (COS-7) cells showed that frameshift mutations in NFIX exons 6-8 generated mutant transcripts that were not cleared by nonsense-mediated-decay mechanisms and encoded truncated NFIX proteins. Moreover, BBX or GFAP expression was unaffected in the majority of MSS fibroblasts. To identify novel NFIX downstream target genes, RNA sequencing and proteomics analyses were performed on mouse embryonic fibroblast (MEF) cells derived from control Nfix+/+, Nfix+/Del2, Nfix+/Del24, NfixDel24/Del24, Nfix+/Del140, and NfixDel140/Del140 mice, compared with NfixDel2/Del2 mice which had developmental, skeletal, and neural abnormalities. This identified 191 transcripts and 815 proteins misregulated in NfixDel2/Del2 MEFs with ≥2-fold-change (P <0 .05). Validation studies using qRT-PCR and western blot analyses confirmed that 2 genes, cellular retinoic acid binding protein 2 (Crabp2) and vascular cell adhesion molecule 1 (Vcam1), were misregulated at the RNA and protein levels in NfixDel2/Del2 MEFs, and that CRABP2 and VCAM1 expressions were altered in 60%-100% of MSS fibroblast cells. Furthermore, in vitro luciferase reporter assays confirmed that NFIX directly regulates CRABP2 promoter activity. Thus, these altered genes and pathways may represent possible targets for drugs as potential treatments and therapies for MSS.

Management of an older Marshall-Smith syndrome patient: a review of literature of MSS and craniosynostosis.

Marshall-Smith Syndrome (MSS) is a rare progressive developmental disorder that severely impairs a patient's intellectual development and physical health. The only known cause for MSS is a mutation in the nuclear factor 1 X (NFIX) gene. This mutation affects neuronal development and protein transcription. Historically, most patients with MSS do not survive beyond 3years of age. Reports of ocular findings are limited. We report a case of a 9-year-old MSS patient with progressive craniosynostosis, elevated intracranial pressure, and catastrophic ocular complications. A comprehensive PubMed literature search from 2018 to August 2022 updating a previous review of older literature produced 72 articles relating to MSS, which are reviewed.

33 - Marshall-Smith syndrome: differentiating allelic disorders

33 - Marshall-Smith syndrome: differentiating allelic disorders

Those blue eyes; an eye opener – A rare case report of Marshall-Smith syndrome

We report a 6-month-old female baby, with dysmorphic facies, recurrent respiratory tract infections, and failure to thrive. A detailed search for genetic causes of failure to thrive including next-generation sequencing revealed the diagnosis of a very rare entity; Marshall–Smith syndrome, a syndrome with very high early mortality. On further evaluation, she was noted to have disordered osseous maturation. She is now on regular follow-up for early intervention and rehabilitation.

A Mouse Model with a Frameshift Mutation in the Nuclear Factor I/X (NFIX) Gene Has Phenotypic Features of Marshall-Smith Syndrome.

The nuclear factor I/X (NFIX) gene encodes a ubiquitously expressed transcription factor whose mutations lead to two allelic disorders characterized by developmental, skeletal, and neural abnormalities, namely, Malan syndrome (MAL) and Marshall-Smith syndrome (MSS). NFIX mutations associated with MAL mainly cluster in exon 2 and are cleared by nonsense-mediated decay (NMD) leading to NFIX haploinsufficiency, whereas NFIX mutations associated with MSS are clustered in exons 6-10 and escape NMD and result in the production of dominant-negative mutant NFIX proteins. Thus, different NFIX mutations have distinct consequences on NFIX expression. To elucidate the in vivo effects of MSS-associated NFIX exon 7 mutations, we used CRISPR-Cas9 to generate mouse models with exon 7 deletions that comprised: a frameshift deletion of two nucleotides (Nfix Del2); in-frame deletion of 24 nucleotides (Nfix Del24); and deletion of 140 nucleotides (Nfix Del140). Nfix +/Del2, Nfix +/Del24, Nfix +/Del140, Nfix Del24/Del24, and Nfix Del140/Del140 mice were viable, normal, and fertile, with no skeletal abnormalities, but Nfix Del2/Del2 mice had significantly reduced viability (p < 0.002) and died at 2-3 weeks of age. Nfix Del2 was not cleared by NMD, and NfixDel2/Del2 mice, when compared to Nfix +/+ and Nfix +/Del2 mice, had: growth retardation; short stature with kyphosis; reduced skull length; marked porosity of the vertebrae with decreased vertebral and femoral bone mineral content; and reduced caudal vertebrae height and femur length. Plasma biochemistry analysis revealed Nfix Del2/Del2 mice to have increased total alkaline phosphatase activity but decreased C-terminal telopeptide and procollagen-type-1-N-terminal propeptide concentrations compared to Nfix +/+ and Nfix +/Del2 mice. Nfix Del2/Del2 mice were also found to have enlarged cerebral cortices and ventricular areas but smaller dentate gyrus compared to Nfix +/+ mice. Thus, Nfix Del2/Del2 mice provide a model for studying the in vivo effects of NFIX mutants that escape NMD and result in developmental abnormalities of the skeletal and neural tissues that are associated with MSS. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Bilateral proptosis in Marshall-Smith syndrome

ABSTRACT Marshall-Smith syndrome (MSS) is an extremely rare developmental disorder characterized by accelerated skeletal maturation, failure to thrive, dysmorphic facies, respiratory difficulties, and neurological abnormalities. Herein, the authors report bilateral proptosis in a 10-year-old child with MSS. At present, there are limited reports on ophthalmologic considerations in MSS; therefore, this article subserves to broaden the clinical spectrum seen in this syndrome.

Nuclear factor I/X (NFIX) regulates the transcriptional activity of the cellular retinoic acid binding protein 2 (CRABP2) promoter and alters CRABP2 expression in Marshall-Smith Syndrome (MSS) patients.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Unusual features in a child with Marshall-Smith syndrome due to a novel NFIX variant: Evidence for an abnormal protein function

Marshall-Smith syndrome (MSS) is a rare genetic condition characterized by different clinical features, such as accelerated skeletal maturation, growth retardation, neuropsychomotor delay, and characteristic facial abnormalities. This study describes a 2-year-old boy presenting longiline appearance, macrocephalus with trigonocephaly, prominent eyes with bluish sclera, middle face hypoplasia, micrognathia, dysplastic ears, hirsutism, narrow and asymmetrical thorax, hypoplastic scrotal sac, cryptorchidism, joint laxity, hypoplastic toenails, and large sacral dimple with prominent coccyx. Abdominal ultrasonography showed an enlarged left ectopic kidney and skull computed tomography revealed signs of early closure of the metopic suture. High-resolution GTG banding karyotype and high-density CytoScan HD array did not identify abnormalities associated to the patient clinical findings. NFIX sequencing revealed a de novo variant consisted of a seven nucleotides duplication in exon 8. We suggest that some clinical findings, as glaucoma, trigonocephaly and ectopic kidney are underestimated and should be considered within the clinical spectrum of the syndrome. In addition, the NFIX variant identified in our patient is unusual among patients with MSS and has not yet been described in the literature. We present some mechanisms that could be involved in the impairment of proper NFIX protein function.

Successful respiratory management of a Marshall-Smith syndrome patient with a tracheo-innominate artery fistula

BackgroundTracheo-innominate artery fistula (TIF) is a life-threatening complication of tracheostomy. We describe perioperative management for innominate artery transection in a case with TIF.Case presentationA 4-year-old Japanese female with Marshal-Smith syndrome presented for management of TIF. She underwent tracheostomy at the age of 3 months and an uncuffed tracheostomy tube was inserted. One month before admission to our hospital, intermittent tracheal bleeding, suggesting TIF, occurred. Although we considered to change to a cuffed endotracheal tube, craniofacial abnormality suggested difficult oral intubation, and there was a possibility of rebleeding. Finally, innominate artery transection was performed under total intravenous anesthesia without changing the tracheostomy tube. Surgery completed uneventfully and she received mechanical ventilation under sedation for a day, followed by weaning without complications.ConclusionsA cuffed tracheostomy tube should have been inserted before surgery for effective hemostasis against sudden bleeding from TIF even though conversion to oral intubation was difficult.

Variants in nuclear factor I genes influence growth and development.

The nuclear factor one (NFI) site-specific DNA-binding proteins represent a family of transcription factors that are important for the development of multiple organ systems, including the brain. During brain development in mice, the expression patterns of Nfia, Nfib, and Nfix overlap, and knockout mice for each of these exhibit overlapping brain defects, including megalencephaly, dysgenesis of the corpus callosum, and enlarged ventricles, which implies a common but not redundant function in brain development. In line with these models, human phenotypes caused by haploinsufficiency of NFIA, NFIB, and NFIX display significant overlap, sharing neurodevelopmental deficits, macrocephaly, brain anomalies, and variable somatic overgrowth. Other anomalies may be present depending on the NFI gene involved. The possibility of variants in NFI genes should therefore be considered in individuals with intellectual disability and brain overgrowth, with individual NFI-related conditions being differentiated from one another by additional signs and symptoms. The exception is provided by specific NFIX variants that act in a dominant negative manner, as these cause a recognizable entity with more severe cognitive impairment and marked bone dysplasia, Marshall-Smith syndrome. NFIX duplications are associated with a phenotype opposite to that of haploinsufficiency, characterized by short stature, small head circumference, and delayed bone age. The spectrum of NFI-related disorders will likely be further expanded, as larger cohorts are assessed.

A mouse model generated by CRISPR-Cas9 with a frameshift mutation in the nuclear factor 1/X (NFIX) gene has phenotypic features reported in Marshall-Smith Syndrome (MSS) patients

A mouse model generated by CRISPR-Cas9 with a frameshift mutation in the nuclear factor 1/X (<i>NFIX</i>) gene has phenotypic features reported in Marshall-Smith Syndrome (MSS) patients

General Anesthesia in a Patient with Marshall-Smith Syndrome

General Anesthesia in a Patient with Marshall-Smith Syndrome

Further delineation of Malan syndrome.

Malan syndrome is an overgrowth disorder described in a limited number of individuals. We aim to delineate the entity by studying a large group of affected individuals. We gathered data on 45 affected individuals with a molecularly confirmed diagnosis through an international collaboration and compared data to the 35 previously reported individuals. Results indicate that height is > 2 SDS in infancy and childhood but in only half of affected adults. Cardinal facial characteristics include long, triangular face, macrocephaly, prominent forehead, everted lower lip, and prominent chin. Intellectual disability is universally present, behaviorally anxiety is characteristic. Malan syndrome is caused by deletions or point mutations of NFIX clustered mostly in exon 2. There is no genotype‐phenotype correlation except for an increased risk for epilepsy with 19p13.2 microdeletions. Variants arose de novo, except in one family in which mother was mosaic. Variants causing Malan and Marshall‐Smith syndrome can be discerned by differences in the site of stop codon formation. We conclude that Malan syndrome has a well recognizable phenotype that usually can be discerned easily from Marshall–Smith syndrome but rarely there is some overlap. Differentiation from Sotos and Weaver syndrome can be made by clinical evaluation only.

Studies of nuclear factor I/X (NFIX) mutations causing the Marshall-Smith syndrome (MSS)

Studies of nuclear factor I/X (NFIX) mutations causing the Marshall-Smith syndrome (MSS)

Mutations in NSD1 and NFIX in Three Patients with Clinical Features of Sotos Syndrome and Malan Syndrome.

Mutations in nuclear receptor SET domain-containing protein 1 gene ( NSD1 ) are related to Sotos syndrome, which is characterized by overgrowth, macrocephaly, distinctive features, and neurodevelopmental disabilities. On the other hand, mutations in the nuclear factor I/X gene ( NFIX ) can lead to Malan syndrome, also known as Sotos-like syndrome, or to the Marshall-Smith syndrome. In this study, using next generation sequencing (NGS), we identified de novo mutations in NSD1 and NFIX in three patients with developmental disabilities associated with overgrowth or macrocephaly. Overall, we confirmed that clinical entities of congenital malformation syndromes can be expanded by molecular diagnoses via NGS.

Marshall-Smith syndrome: Novel pathogenic variant and previously unreported associations with precocious puberty and aortic root dilatation

Marshall-Smith Syndrome (MRSHSS) is a very rare genetic disorder characterized by failure to thrive and characteristic dysmorphic features associated with accelerated osseous maturation. We present a nine-year-old girl who was diagnosed with MRSHSS based on characteristic clinical features supported by the identification of a novel de novo pathogenic variant in the NFIX gene. The patient also presented with precocious puberty diagnosed at five years of age and had an abnormal GnRH stimulation test indicative of central precocious puberty. Central precocious puberty has not been described in association with MRSHSS previously in the medical literature and broadens our knowledge of the natural history of MRSHSS. The causes of advanced bone age in this syndrome are also reviewed. Additionally, the patient showed progressive dilatation of the aortic root. Although connective tissue abnormalities have been described in association with MRSHSS, aortic root dilatation has not. Understanding the mechanism of comorbidities such as advanced bone age and aortic root dilatation in MRSHSS patients enables future development of anticipatory guidance, preventative care measures, and treatment guidelines.

Exploring the N-ethyl-N-nitrosourea mutagenesis DNA archive for mutations in nuclear factor I/X to derive mouse models for Marshall-Smith syndrome

Exploring the N-ethyl-N-nitrosourea mutagenesis DNA archive for mutations in nuclear factor I/X to derive mouse models for Marshall-Smith syndrome

NFIX mutations affecting the DNA-binding domain cause a peculiar overgrowth syndrome (Malan syndrome): A new patients series

The Nuclear Factor I-X (NFIX) is a member of the nuclear factor I (NFI) protein family and is deleted or mutated in a subset of patients with a peculiar overgrowth condition resembling Sotos Syndrome as well as in patients with Marshall-Smith syndrome. We identified three additional patients with this phenotype each carrying a different new mutation affecting the DNA-binding/dimerization domain of the NFIX protein. The present report further adds weight to the hypothesis that mutations in DNA-binding/dimerization domain are likely to cause haploinsufficiency of the NFIX protein and confirms that NFIX is the second gene that should be tested in individuals with overgrowth conditions resembling Sotos syndrome, previously tested negative for NSD1 mutations. We then propose to consider this overgrowth syndrome (namely Malan syndrome) and Marshall-Smith syndrome NFIX-related diseases.

Deletions in the 3′ Part of theNFIXGene Including a Recurrent Alu-Mediated Deletion of Exon 6 and 7 Account for Previously Unexplained Cases of Marshall-Smith Syndrome

Marshall-Smith syndrome (MSS) is a very rare malformation syndrome characterized by typical craniofacial anomalies, abnormal osseous maturation, developmental delay, failure to thrive, and respiratory difficulties. Mutations in the nuclear factor 1/X gene (NFIX) were recently identified as the cause of MSS. In our study cohort of 17 patients with a clinical diagnosis of MSS, conventional sequencing of NFIX revealed frameshift and splice-site mutations in 10 individuals. Using multiplex ligation-dependent probe amplification analysis, we identified a recurrent deletion of NFIX exon 6 and 7 in five individuals. We demonstrate this recurrent deletion is the product of a recombination between AluY elements located in intron 5 and 7. Two other patients had smaller deletions affecting exon 6. These findings show that MSS is a genetically homogeneous Mendelian disorder. RT-PCR experiments with newly identified NFIX mutations including the recurrent exon 6 and 7 deletion confirmed previous findings indicating that MSS-associated mutant mRNAs are not cleared by nonsense-mediated mRNA decay. Predicted MSS-associated mutant NFIX proteins consistently have a preserved DNA binding and dimerization domain, whereas they grossly vary in their C-terminal portion. This is in line with the hypothesis that MSS-associated mutations encode dysfunctional proteins that act in a dominant negative manner.