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1.
J Biol Chem ; 299(8): 105012, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37414152

RESUMEN

Inosine 5' monophosphate dehydrogenase (IMPDH) is a critical regulatory enzyme in purine nucleotide biosynthesis that is inhibited by the downstream product GTP. Multiple point mutations in the human isoform IMPDH2 have recently been associated with dystonia and other neurodevelopmental disorders, but the effect of the mutations on enzyme function has not been described. Here, we report the identification of two additional missense variants in IMPDH2 from affected individuals and show that all of the disease-associated mutations disrupt GTP regulation. Cryo-EM structures of one IMPDH2 mutant suggest this regulatory defect arises from a shift in the conformational equilibrium toward a more active state. This structural and functional analysis provides insight into IMPDH2-associated disease mechanisms that point to potential therapeutic approaches and raises new questions about fundamental aspects of IMPDH regulation.


Asunto(s)
IMP Deshidrogenasa , Purinas , Humanos , Regulación Alostérica , IMP Deshidrogenasa/genética , IMP Deshidrogenasa/metabolismo , Mutación , Guanosina Trifosfato
2.
J Pediatr ; 265: 113808, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37923198

RESUMEN

OBJECTIVE: To assess the diagnostic yield of exome sequencing (ES) in pediatric cardiomyopathy. STUDY DESIGN: A single-institution, retrospective chart review of 91 patients with pediatric cardiomyopathy was performed. While pediatric cardiomyopathy is often genetic in nature, no genetic test is recommended as standard of care. All our patients were diagnosed with cardiomyopathy and evaluated by a medical geneticist between January 2010 through September 2022. Demographic information and clinical data were abstracted. RESULTS: Of 91 patients with pediatric cardiomyopathy, 36 (39.6%) received a diagnosis by ES. Twenty-two (61.1%) of these diagnoses would have been missed on cardiac multigene panel testing. The diagnostic yield for cardiomyopathy presenting under 1 year of age was 38.3%, while the yield for patients over 1 year of age was 41.9%. CONCLUSIONS: ES has a high diagnostic yield in pediatric cardiomyopathy compared with a gene panel. Over 60% of patients with diagnosis by ES would not have received their molecular genetic diagnosis if only multigene panel testing was sent. Diagnostic yield did not vary significantly between the subtypes of cardiomyopathy and patient age groups, highlighting the likely clinical utility of ES for all pediatric cardiomyopathy patients.


Asunto(s)
Cardiomiopatías , Médicos , Humanos , Niño , Secuenciación del Exoma , Estudios Retrospectivos , Pruebas Genéticas , Cardiomiopatías/diagnóstico , Cardiomiopatías/genética
3.
Am J Med Genet A ; : e63816, 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-39007708

RESUMEN

RFX7 encodes a transcription factor that is ubiquitously expressed and important for neural development. Haploinsufficiency of RFX7 is associated with intellectual disability, developmental delay, and diverse malformations of brain structures. Currently, there are only 16 clinically described individuals who have variants in RFX7. A recognizable pattern of malformation associated with mutation in RFX7 has not yet been uncovered. Here we describe the phenotypic presentation of two additional individuals who have novel de novo variants in RFX7. One of the individuals we describe is from an under-represented Afro-Caribbean population.

4.
J Genet Couns ; 2024 Apr 29.
Artículo en Inglés | MEDLINE | ID: mdl-38682751

RESUMEN

The dystrophinopathies encompass the phenotypically variable forms of muscular dystrophy caused by pathogenic variants in the DMD gene. The dystrophinopathies include the most common inherited muscular dystrophy among 46,XY individuals, Duchenne muscular dystrophy, as well as Becker muscular dystrophy and other less common phenotypic variants. With increased access to and utilization of genetic testing in the diagnostic and carrier setting, genetic counselors and clinicians in diverse specialty areas may care for individuals with and carriers of dystrophinopathy. This practice resource was developed as a tool for genetic counselors and other health care professionals to support counseling regarding dystrophinopathies, including diagnosis, health risks and management, psychosocial needs, reproductive options, clinical trials, and treatment. Genetic testing efforts have enabled genotype/phenotype correlation in the dystrophinopathies, but have also revealed unexpected findings, further complicating genetic counseling for this group of conditions. Additionally, the therapeutic landscape for dystrophinopathies has dramatically changed with several FDA-approved therapeutics, an expansive research pathway, and numerous clinical trials. Genotype-phenotype correlations are especially complex and genetic counselors' unique skill sets are useful in exploring and explaining this to families. Given the recent advances in diagnostic testing and therapeutics related to dystrophinopathies, this practice resource is a timely update for genetic counselors and other healthcare professionals involved in the diagnosis and care of individuals with dystrophinopathies.

5.
Am J Med Genet C Semin Med Genet ; 193(2): 128-138, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37296540

RESUMEN

Kabuki syndrome is a recognizable Mendelian disorder characterized by the clinical constellation of childhood hypotonia, developmental delay or intellectual impairment, and characteristic dysmorphism resulting from monoallelic pathogenic variants in KMT2D or KDM6A. In the medical literature, most reported patients are children, and data is lacking on the natural history of the condition across the lifespan, with little known about adult-specific presentations and symptoms. Here, we report the results of a retrospective chart review of eight adult patients with Kabuki syndrome, seven of whom are molecularly confirmed. We use their trajectories to highlight the diagnostic challenges unique to an adult population, expand on neurodevelopmental/psychiatric phenotypes across the lifespan, and describe adult-onset medical complications, including a potential cancer risk and unusual and striking premature/accelerated aging phenotype.


Asunto(s)
Anomalías Múltiples , Enfermedades Hematológicas , Humanos , Estudios Retrospectivos , Anomalías Múltiples/diagnóstico , Anomalías Múltiples/genética , Anomalías Múltiples/patología , Cara/patología , Enfermedades Hematológicas/diagnóstico , Enfermedades Hematológicas/genética , Enfermedades Hematológicas/complicaciones , Fenotipo , Mutación
6.
Genet Med ; 25(8): 100863, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37125634

RESUMEN

PURPOSE: Bone morphogenic proteins (BMPs) regulate gene expression that is related to many critical developmental processes, including osteogenesis for which they are named. In addition, BMP2 is widely expressed in cells of mesenchymal origin, including bone, cartilage, skeletal and cardiac muscle, and adipose tissue. It also participates in neurodevelopment by inducing differentiation of neural stem cells. In humans, BMP2 variants result in a multiple congenital anomaly syndrome through a haploinsufficiency mechanism. We sought to expand the phenotypic spectrum and highlight phenotypes of patients harboring monoallelic missense variants in BMP2. METHODS: We used retrospective chart review to examine phenotypes from an international cohort of 18 individuals and compared these with published cases. Patient-derived missense variants were modeled in zebrafish to examine their effect on the ability of bmp2b to promote embryonic ventralization. RESULTS: The presented cases recapitulated existing descriptions of BMP2-related disorders, including craniofacial, cardiac, and skeletal anomalies and exhibit a wide phenotypic spectrum. We also identified patients with neural tube defects, structural brain anomalies, and endocrinopathies. Missense variants modeled in zebrafish resulted in loss of protein function. CONCLUSION: We use this expansion of reported phenotypes to suggest multidisciplinary medical monitoring and management of patients with BMP2-related skeletal dysplasia spectrum.


Asunto(s)
Osteocondrodisplasias , Pez Cebra , Animales , Humanos , Pez Cebra/genética , Estudios Retrospectivos , Diferenciación Celular , Osteogénesis/genética , Proteínas Morfogenéticas Óseas , Proteína Morfogenética Ósea 2/genética
7.
Genet Med ; 25(7): 100861, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37087635

RESUMEN

PURPOSE: This study aimed to establish variants in CBX1, encoding heterochromatin protein 1ß (HP1ß), as a cause of a novel syndromic neurodevelopmental disorder. METHODS: Patients with CBX1 variants were identified, and clinician researchers were connected using GeneMatcher and physician referrals. Clinical histories were collected from each patient. To investigate the pathogenicity of identified variants, we performed in vitro cellular assays and neurobehavioral and cytological analyses of neuronal cells obtained from newly generated Cbx1 mutant mouse lines. RESULTS: In 3 unrelated individuals with developmental delay, hypotonia, and autistic features, we identified heterozygous de novo variants in CBX1. The identified variants were in the chromodomain, the functional domain of HP1ß, which mediates interactions with chromatin. Cbx1 chromodomain mutant mice displayed increased latency-to-peak response, suggesting the possibility of synaptic delay or myelination deficits. Cytological and chromatin immunoprecipitation experiments confirmed the reduction of mutant HP1ß binding to heterochromatin, whereas HP1ß interactome analysis demonstrated that the majority of HP1ß-interacting proteins remained unchanged between the wild-type and mutant HP1ß. CONCLUSION: These collective findings confirm the role of CBX1 in developmental disabilities through the disruption of HP1ß chromatin binding during neurocognitive development. Because HP1ß forms homodimers and heterodimers, mutant HP1ß likely sequesters wild-type HP1ß and other HP1 proteins, exerting dominant-negative effects.


Asunto(s)
Homólogo de la Proteína Chromobox 5 , Heterocromatina , Animales , Ratones , Cromatina/genética , Proteínas Cromosómicas no Histona/genética , Histonas/genética , Histonas/metabolismo
8.
Am J Med Genet A ; 191(10): 2602-2609, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37159414

RESUMEN

Eukaryotic translation elongation factor 2 (eEF2), encoded by the gene EEF2, is an essential factor involved in the elongation phase of protein translation. A specific heterozygous missense variant (p.P596H) in EEF2 was originally identified in association with autosomal dominant adult-onset spinocerebellar ataxia-26 (SCA26). More recently, additional heterozygous missense variants in this gene have been described to cause a novel, childhood-onset neurodevelopmental disorder with benign external hydrocephalus. Herein, we report two unrelated individuals with a similar gene-disease correlation to support this latter observation. Patient 1 is a 7-year-old male with a previously reported, de novo missense variant (p.V28M) who has motor and speech delay, autism spectrum disorder, failure to thrive with relative macrocephaly, unilateral microphthalmia with coloboma and eczema. Patient 2 is a 4-year-old female with a novel de novo nonsense variant (p.Q145X) with motor and speech delay, hypotonia, macrocephaly with benign ventricular enlargement, and keratosis pilaris. These additional cases help to further expand the genotypic and phenotypic spectrum of this newly described EEF2-related neurodevelopmental syndrome.


Asunto(s)
Trastorno del Espectro Autista , Discapacidad Intelectual , Trastornos del Desarrollo del Lenguaje , Trastornos del Neurodesarrollo , Masculino , Adulto , Femenino , Humanos , Niño , Preescolar , Trastorno del Espectro Autista/genética , Factor 2 de Elongación Peptídica/genética , Trastornos del Neurodesarrollo/genética , Trastornos del Desarrollo del Lenguaje/genética , Genotipo , Discapacidad Intelectual/genética , Fenotipo
9.
Am J Med Genet A ; 191(8): 2149-2155, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37212523

RESUMEN

SRRM2-related neurodevelopmental disorder is a recently described genetic diagnosis caused by loss-of-function variants in SRRM2. In order to understand the clinical spectrum of SRRM2-related neurodevelopmental disorder, we performed a retrospective exome data and clinical chart review at a single tertiary children's hospital, Children's Hospital of Philadelphia (CHOP). Among approximately 3100 clinical exome sequencing cases performed at CHOP, we identified three patients with SRRM2 loss-of-function pathogenic variants, in addition to one patient previously described in the literature. Common clinical features include developmental delay, attention deficit hyperactivity disorder, macrocephaly, hypotonia, gastroesophageal reflux, overweight/obesity, and autism. While developmental disabilities are commonly seen in all individuals with SRRM2 variants, the degree of developmental delay and intellectual disability is variable. Our data suggest that SRRM2-related neurodevelopmental disorder can be identified in 0.3% of individuals with developmental disabilities receiving exome sequencing.


Asunto(s)
Discapacidad Intelectual , Trastornos del Neurodesarrollo , Humanos , Niño , Discapacidades del Desarrollo/genética , Discapacidades del Desarrollo/patología , Estudios Retrospectivos , Trastornos del Neurodesarrollo/diagnóstico , Trastornos del Neurodesarrollo/genética , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/genética , Discapacidad Intelectual/patología , Hospitales , Proteínas de Unión al ARN
11.
Genes (Basel) ; 15(7)2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-39062646

RESUMEN

PURPOSE: Genetic counselors (GCs) increasingly play key roles in advancing genomic medicine through innovative research. Here, we examine one large cohort of GCs' evolving contributions to the literature, with the goal of facilitating worldwide professional development for GCs through scholarly activities. METHODS: Publications were cataloged by members of the Section of Genetic Counseling (Section), established at the Children's Hospital of Philadelphia and the University of Pennsylvania in 2014, including publication year, journal, impact factor, and author position. Data were organized using the "My Bibliography" tool on the National Center for Biotechnology Information website and a Research Electronic Data Capture database created to initially collect manuscripts published through 30 June 2020. A subsequent survey captured publications through 5 February 2024. RESULTS: An amount of 52 of 120 (43%) GCs shared their curriculum vitae/papers. 992 unique publications were identified from 1986 to 2024. Since 2013, no less than 32 papers were published annually by Section members and no less than 10 GCs contributed to publications yearly. Impact factors typically averaged >5.0 per year. Areas of foci diversified considerably since 2015. CONCLUSIONS: Here, we establish that GCs indeed contribute to scholarly work as evidenced by the number of publications alone. The establishment of an academic home may have contributed, given publications increased concurrent to launching the Section, providing a model for organizing GCs at institutions nationally and internationally. Highlighting such achievements will foster the expansion of GC roles in the era of precision genomic medicine and therapy. Considering ways to support GCs towards expanding these activities is equally important.


Asunto(s)
Asesoramiento Genético , Humanos , Consejeros , Factor de Impacto de la Revista
12.
medRxiv ; 2024 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-38260255

RESUMEN

SPOUT1/CENP-32 encodes a putative SPOUT RNA methyltransferase previously identified as a mitotic chromosome associated protein. SPOUT1/CENP-32 depletion leads to centrosome detachment from the spindle poles and chromosome misalignment. Aided by gene matching platforms, we identified 24 individuals with neurodevelopmental delays from 18 families with bi-allelic variants in SPOUT1/CENP-32 detected by exome/genome sequencing. Zebrafish spout1/cenp-32 mutants showed reduction in larval head size with concomitant apoptosis likely associated with altered cell cycle progression. In vivo complementation assays in zebrafish indicated that SPOUT1/CENP-32 missense variants identified in humans are pathogenic. Crystal structure analysis of SPOUT1/CENP-32 revealed that most disease-associated missense variants mapped to the catalytic domain. Additionally, SPOUT1/CENP-32 recurrent missense variants had reduced methyltransferase activity in vitro and compromised centrosome tethering to the spindle poles in human cells. Thus, SPOUT1/CENP-32 pathogenic variants cause an autosomal recessive neurodevelopmental disorder: SpADMiSS ( SPOUT1 Associated Development delay Microcephaly Seizures Short stature) underpinned by mitotic spindle organization defects and consequent chromosome segregation errors.

13.
bioRxiv ; 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36993700

RESUMEN

Inosine 5' monophosphate dehydrogenase (IMPDH) is a critical regulatory enzyme in purine nucleotide biosynthesis that is inhibited by the downstream product GTP. Multiple point mutations in the human isoform IMPDH2 have recently been associated with dystonia and other neurodevelopmental disorders, but the effect of the mutations on enzyme function has not been described. Here, we report identification of two additional affected individuals with missense variants in IMPDH2 and show that all of the disease-associated mutations disrupt GTP regulation. Cryo-EM structures of one IMPDH2 mutant suggest this regulatory defect arises from a shift in the conformational equilibrium toward a more active state. This structural and functional analysis provides insight into IMPDH2-associated disease mechanisms that point to potential therapeutic approaches and raises new questions about fundamental aspects of IMPDH regulation.

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