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1.
J Clin Invest ; 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001864

RESUMO

BACKGROUND: Transcriptome sequencing (RNA-seq) improves diagnostic rates in individuals with suspected Mendelian conditions to varying degrees, primarily by directing the prioritization of candidate DNA variants identified on exome or genome sequencing (ES/GS). Here we implemented an RNA-seq guided method to diagnose individuals across a wide range of ages and clinical phenotypes. METHODS: One hundred fifteen undiagnosed adult and pediatric patients with diverse phenotypes and 67 family members (182 total individuals) underwent RNA-seq from whole blood and fibroblasts at the Baylor College of Medicine (BCM) Undiagnosed Diseases Network (UDN) clinical site from 2014-2020. We implemented a workflow to detect outliers in gene expression and splicing for cases that remained undiagnosed despite standard genomic and transcriptomic analysis. RESULTS: The transcriptome-directed approach resulted in a diagnostic rate of 12% across the entire cohort, or 17% after excluding cases solved on ES/GS alone. Newly diagnosed conditions included Koolen-de Vries syndrome (KANSL1), Renpenning syndrome (PQBP1), TBCK-associated encephalopathy, NSD2- and CLTC-related intellectual disability, and others, all with negative conventional genomic testing, including ES and chromosomal microarray (CMA). Fibroblasts exhibited higher and more consistent expression of clinically relevant genes than whole blood. In solved cases with RNA-seq from both tissues, the causative defect was missed in blood in half the cases but none from fibroblasts. CONCLUSION: For our cohort of undiagnosed individuals with suspected Mendelian conditions, transcriptome-directed genomic analysis facilitated diagnoses, primarily through the identification of variants missed on ES and CMA.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32940150

RESUMO

Bone is a highly vascularized organ, providing structural support to the body, and its development, regeneration, and remodeling depend on the microvascular homeostasis. Loss or impairment of vascular function can develop diseases, such as large bone defects, avascular necrosis, osteoporosis, osteoarthritis, and osteopetrosis. In this review, we summarize how vasculature controls bone development and homeostasis in normal and disease cases. A better understanding of this process will facilitate the development of novel disease treatments that promote bone regeneration and remodeling. Specifically, approaches based on tissue engineering components, such as stem cells and growth factors, have demonstrated the capacity to induce bone microvasculature regeneration and mineralization. This knowledge will have relevant clinical implications for the treatment of bone disorders by developing novel pharmaceutical approaches and bone grafts. Finally, the tissue engineering approaches incorporating vascular components may widely be applied to treat other organ diseases by enhancing their regeneration capacity. Impact statement Bone vasculature is imperative in the process of bone development, regeneration, and remodeling. Alterations or disruption of the bone vasculature leads to loss of bone homeostasis and the development of bone diseases. In this study, we review the role of vasculature on bone diseases and how vascular tissue engineering strategies, with a detailed emphasis on the role of stem cells and growth factors, will contribute to bone therapeutics.

3.
Am J Med Genet A ; 182(9): 2058-2067, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32686290

RESUMO

SMARCA4 encodes a central ATPase subunit in the BRG1-/BRM-associated factors (BAF) or polybromo-associated BAF (PBAF) complex in humans, which is responsible in part for chromatin remodeling and transcriptional regulation. Variants in this and other genes encoding BAF/PBAF complexes have been implicated in Coffin-Siris Syndrome, a multiple congenital anomaly syndrome classically characterized by learning and developmental differences, coarse facial features, hypertrichosis, and underdevelopment of the fifth digits/nails of the hands and feet. Individuals with SMARCA4 variants have been previously reported and appear to display a variable phenotype. We describe here a cohort of 15 unrelated individuals with SMARCA4 variants from the Coffin-Siris syndrome/BAF pathway disorders registry who further display variability in severity and degrees of learning impairment and health issues. Within this cohort, we also report two individuals with novel nonsense variants who appear to have a phenotype of milder learning/behavioral differences and no organ-system involvement.

4.
Eur J Hum Genet ; 28(10): 1422-1431, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32483341

RESUMO

There has been one previous report of a cohort of patients with variants in Chromodomain Helicase DNA-binding 3 (CHD3), now recognized as Snijders Blok-Campeau syndrome. However, with only three previously-reported patients with variants outside the ATPase/helicase domain, it was unclear if variants outside of this domain caused a clinically similar phenotype. We have analyzed 24 new patients with CHD3 variants, including nine outside the ATPase/helicase domain. All patients were detected with unbiased molecular genetic methods. There is not a significant difference in the clinical or facial features of patients with variants in or outside this domain. These additional patients further expand the clinical and molecular data associated with CHD3 variants. Importantly we conclude that there is not a significant difference in the phenotypic features of patients with various molecular disruptions, including whole gene deletions and duplications, and missense variants outside the ATPase/helicase domain. This data will aid both clinical geneticists and molecular geneticists in the diagnosis of this emerging syndrome.

5.
Neuron ; 106(5): 759-768.e7, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32243781

RESUMO

Autism spectrum disorder (ASD) is more prevalent in males; however, the etiology for this sex bias is not well understood. Many mutations on X-linked cell adhesion molecule NLGN4X result in ASD or intellectual disability. NLGN4X is part of an X-Y pair, with NLGN4Y sharing ∼97% sequence homology. Using biochemistry, electrophysiology, and imaging, we show that NLGN4Y displays severe deficits in maturation, surface expression, and synaptogenesis regulated by one amino acid difference with NLGN4X. Furthermore, we identify a cluster of ASD-associated mutations surrounding the critical amino acid in NLGN4X, and these mutations phenocopy NLGN4Y. We show that NLGN4Y cannot compensate for the functional deficits observed in ASD-associated NLGN4X mutations. Altogether, our data reveal a potential pathogenic mechanism for male bias in NLGN4X-associated ASD.


Assuntos
Moléculas de Adesão Celular Neuronais/genética , Cromossomos Humanos X/genética , Cromossomos Humanos Y/genética , Neurônios/metabolismo , Transtorno do Espectro Autista/genética , Moléculas de Adesão Celular Neuronais/metabolismo , Feminino , Predisposição Genética para Doença , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas , Deficiência Intelectual/genética , Masculino , Mutação , Transporte Proteico/genética
6.
JBMR Plus ; 4(3): e10335, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32161841

RESUMO

Worldwide, one in five men aged over 50 years will experience osteoporosis or a clinical bone fracture, with a greater fracture-related mortality rate than women. However, the genetic etiology of osteoporosis in men is still poorly understood. We aimed to identify the genetic variants and candidate genes associated with extremely low or high BMD for a better understanding of the biology underlying low bone density that may point to potential therapeutic targets for increasing bone mass. Subjects from the Osteoporotic Fractures in Men Study (MrOS) cohort were evaluated by age and BMI-adjusted total hip BMD. Those with BMD values 3 SDs away from the mean were selected and the remaining individuals whose adjusted BMD ranked at the highest or lowest 100 were included. Men with the lowest adjusted BMD (N = 98) and highest adjusted BMD (N = 110) were chosen for exome sequencing. Controls (N = 82) were men of Northern and Western European descent from the US Utah population of the 1000 Genomes Project. Fisher's exact test was performed to compare low- or high-BMD subjects with controls for single-gene associations. Additionally, sets of candidate genes causative of heritable disorders of connective tissue, including osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS), were grouped for multigene and mutation burden analyses. No single-gene associations with rare variants were found for either the low BMD group (33 genes) or high BMD group (18 genes). In the group of OI genes, we detected a significant threefold increased accumulation of rare variants in low-BMD subjects compared with controls (p = 0.009). Additionally, genes associated with EDS had a twofold increased frequency in low-BMD subjects compared with controls (p = 0.03). These findings reveal a rare variant burden in OI and EDS disease genes at low BMD, which suggests a potential gene-panel approach to screen for multivariant associations in larger cohorts. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

7.
Am J Hum Genet ; 106(4): 570-583, 2020 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-32197074

RESUMO

EIF2AK1 and EIF2AK2 encode members of the eukaryotic translation initiation factor 2 alpha kinase (EIF2AK) family that inhibits protein synthesis in response to physiologic stress conditions. EIF2AK2 is also involved in innate immune response and the regulation of signal transduction, apoptosis, cell proliferation, and differentiation. Despite these findings, human disorders associated with deleterious variants in EIF2AK1 and EIF2AK2 have not been reported. Here, we describe the identification of nine unrelated individuals with heterozygous de novo missense variants in EIF2AK1 (1/9) or EIF2AK2 (8/9). Features seen in these nine individuals include white matter alterations (9/9), developmental delay (9/9), impaired language (9/9), cognitive impairment (8/9), ataxia (6/9), dysarthria in probands with verbal ability (6/9), hypotonia (7/9), hypertonia (6/9), and involuntary movements (3/9). Individuals with EIF2AK2 variants also exhibit neurological regression in the setting of febrile illness or infection. We use mammalian cell lines and proband-derived fibroblasts to further confirm the pathogenicity of variants in these genes and found reduced kinase activity. EIF2AKs phosphorylate eukaryotic translation initiation factor 2 subunit 1 (EIF2S1, also known as EIF2α), which then inhibits EIF2B activity. Deleterious variants in genes encoding EIF2B proteins cause childhood ataxia with central nervous system hypomyelination/vanishing white matter (CACH/VWM), a leukodystrophy characterized by neurologic regression in the setting of febrile illness and other stressors. Our findings indicate that EIF2AK2 missense variants cause a neurodevelopmental syndrome that may share phenotypic and pathogenic mechanisms with CACH/VWM.


Assuntos
Deficiências do Desenvolvimento/genética , Variação Genética/genética , Leucoencefalopatias/genética , Malformações do Sistema Nervoso/genética , eIF-2 Quinase/genética , Adolescente , Ataxia/genética , Criança , Pré-Escolar , Feminino , Doenças Desmielinizantes Hereditárias do Sistema Nervoso Central/genética , Humanos , Lactente , Masculino , Substância Branca/patologia
8.
Am J Med Genet C Semin Med Genet ; 184(1): 124-128, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32030882

RESUMO

Sudden cardiac death (SCD) is one of the leading causes of mortality in the U.S. military and competitive athletes. In this study, we simulate how genetic screening may be implemented in the military to prevent an SCD endpoint resulting from hypertrophic cardiomyopathy (HCM). We created a logistic regression model to predict variant pathogenicity in the most common HCM associated genes MYH7 and MYBPC3. Model predictions were used in conjunction with the gnomAD database to identify frequencies of pathogenic variants. Extrapolating these variants to a military population, lives saved and cost benefit analyses were conducted for screening for HCM related to pathogenic variants in MYH7 and MYBPC3. Genetic screening for HCM followed by echocardiography in individuals with pathogenic variants is predicted to save an average of 2.9 lives per accession cohort, based on historical cohort sizes, and result in a break-even cost of ~$7 per test. The false positives, defined as disqualified individuals for military service who do not have HCM, are predicted to be 0 individuals per accession cohort. This study suggests that the main barriers for the implementation of genetic screening for the U.S. military are the low detection rate and variant interpretation.

9.
Exp Neurol ; 326: 113164, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31887305

RESUMO

Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a rare, slowly progressive white matter disease caused by mutations in the mitochondrial aspartyl-tRNA synthetase (mt-AspRS, or DARS2). While patients show characteristic MRI T2 signal abnormalities throughout the cerebral white matter, brainstem, and spinal cord, the phenotypic spectrum is broad and a multitude of gene variants have been associated with the disease. Here, Dars2 disruption in CamKIIα-expressing cortical and hippocampal neurons results in slowly progressive increases in behavioral activity at five months, and culminating by nine months as severe brain atrophy, behavioral dysfunction, reduced corpus callosum thickness, and microglial morphology indicative of neuroinflammation. Interestingly, RNAseq based gene expression studies performed prior to the presentation of this severe phenotype reveal the upregulation of several pathways involved in immune activation, cytokine production and signaling, and defense response regulation. RNA transcript analysis demonstrates that activation of immune and cell stress pathways are initiated in advance of a behavioral phenotype and cerebral deficits. An understanding of these pathways and their contribution to significant neuronal loss in CamKII-Dars2 deficient mice may aid in deciphering mechanisms of LBSL pathology.


Assuntos
Aspartato-tRNA Ligase/genética , Leucoencefalopatias/fisiopatologia , Mitocôndrias/enzimologia , Animais , Atrofia , Comportamento Animal , Encéfalo/patologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Córtex Cerebral/metabolismo , Corpo Caloso/parasitologia , Hipocampo/metabolismo , Leucoencefalopatias/genética , Leucoencefalopatias/psicologia , Imagem por Ressonância Magnética , Camundongos , Camundongos Knockout , Neurônios/metabolismo
11.
Genet Med ; 22(2): 389-397, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31388190

RESUMO

PURPOSE: Sifrim-Hitz-Weiss syndrome (SIHIWES) is a recently described multisystemic neurodevelopmental disorder caused by de novo variants inCHD4. In this study, we investigated the clinical spectrum of the disorder, genotype-phenotype correlations, and the effect of different missense variants on CHD4 function. METHODS: We collected clinical and molecular data from 32 individuals with mostly de novo variants in CHD4, identified through next-generation sequencing. We performed adenosine triphosphate (ATP) hydrolysis and nucleosome remodeling assays on variants from five different CHD4 domains. RESULTS: The majority of participants had global developmental delay, mild to moderate intellectual disability, brain anomalies, congenital heart defects, and dysmorphic features. Macrocephaly was a frequent but not universal finding. Additional common abnormalities included hypogonadism in males, skeletal and limb anomalies, hearing impairment, and ophthalmic abnormalities. The majority of variants were nontruncating and affected the SNF2-like region of the protein. We did not identify genotype-phenotype correlations based on the type or location of variants. Alterations in ATP hydrolysis and chromatin remodeling activities were observed in variants from different domains. CONCLUSION: The CHD4-related syndrome is a multisystemic neurodevelopmental disorder. Missense substitutions in different protein domains alter CHD4 function in a variant-specific manner, but result in a similar phenotype in humans.

12.
Nat Commun ; 10(1): 3094, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300657

RESUMO

AMPA receptors (AMPARs) are tetrameric ligand-gated channels made up of combinations of GluA1-4 subunits encoded by GRIA1-4 genes. GluA2 has an especially important role because, following post-transcriptional editing at the Q607 site, it renders heteromultimeric AMPARs Ca2+-impermeable, with a linear relationship between current and trans-membrane voltage. Here, we report heterozygous de novo GRIA2 mutations in 28 unrelated patients with intellectual disability (ID) and neurodevelopmental abnormalities including autism spectrum disorder (ASD), Rett syndrome-like features, and seizures or developmental epileptic encephalopathy (DEE). In functional expression studies, mutations lead to a decrease in agonist-evoked current mediated by mutant subunits compared to wild-type channels. When GluA2 subunits are co-expressed with GluA1, most GRIA2 mutations cause a decreased current amplitude and some also affect voltage rectification. Our results show that de-novo variants in GRIA2 can cause neurodevelopmental disorders, complementing evidence that other genetic causes of ID, ASD and DEE also disrupt glutamatergic synaptic transmission.


Assuntos
Deficiência Intelectual/genética , Transtornos do Neurodesenvolvimento/genética , Receptores de AMPA/genética , Adolescente , Adulto , Encéfalo/diagnóstico por imagem , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Heterozigoto , Humanos , Lactente , Mutação com Perda de Função , Imagem por Ressonância Magnética , Masculino , Transtornos do Neurodesenvolvimento/diagnóstico por imagem , Adulto Jovem
13.
Hum Mutat ; 40(7): 908-925, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30817854

RESUMO

Pathogenic de novo variants in the X-linked gene SLC35A2 encoding the major Golgi-localized UDP-galactose transporter required for proper protein and lipid glycosylation cause a rare type of congenital disorder of glycosylation known as SLC35A2-congenital disorders of glycosylation (CDG; formerly CDG-IIm). To date, 29 unique de novo variants from 32 unrelated individuals have been described in the literature. The majority of affected individuals are primarily characterized by varying degrees of neurological impairments with or without skeletal abnormalities. Surprisingly, most affected individuals do not show abnormalities in serum transferrin N-glycosylation, a common biomarker for most types of CDG. Here we present data characterizing 30 individuals and add 26 new variants, the single largest study involving SLC35A2-CDG. The great majority of these individuals had normal transferrin glycosylation. In addition, expanding the molecular and clinical spectrum of this rare disorder, we developed a robust and reliable biochemical assay to assess SLC35A2-dependent UDP-galactose transport activity in primary fibroblasts. Finally, we show that transport activity is directly correlated to the ratio of wild-type to mutant alleles in fibroblasts from affected individuals.


Assuntos
Defeitos Congênitos da Glicosilação/genética , Proteínas de Transporte de Monossacarídeos/genética , Proteínas de Transporte de Monossacarídeos/metabolismo , Uridina Difosfato Galactose/metabolismo , Animais , Biópsia , Células CHO , Células Cultivadas , Defeitos Congênitos da Glicosilação/metabolismo , Defeitos Congênitos da Glicosilação/patologia , Cricetulus , Feminino , Humanos , Masculino , Mutação
14.
Am J Hum Genet ; 104(3): 422-438, 2019 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-30773277

RESUMO

SPONASTRIME dysplasia is an autosomal-recessive spondyloepimetaphyseal dysplasia characterized by spine (spondylar) abnormalities, midface hypoplasia with a depressed nasal bridge, metaphyseal striations, and disproportionate short stature. Scoliosis, coxa vara, childhood cataracts, short dental roots, and hypogammaglobulinemia have also been reported in this disorder. Although an autosomal-recessive inheritance pattern has been hypothesized, pathogenic variants in a specific gene have not been discovered in individuals with SPONASTRIME dysplasia. Here, we identified bi-allelic variants in TONSL, which encodes the Tonsoku-like DNA repair protein, in nine subjects (from eight families) with SPONASTRIME dysplasia, and four subjects (from three families) with short stature of varied severity and spondylometaphyseal dysplasia with or without immunologic and hematologic abnormalities, but no definitive metaphyseal striations at diagnosis. The finding of early embryonic lethality in a Tonsl-/- murine model and the discovery of reduced length, spinal abnormalities, reduced numbers of neutrophils, and early lethality in a tonsl-/- zebrafish model both support the hypomorphic nature of the identified TONSL variants. Moreover, functional studies revealed increased amounts of spontaneous replication fork stalling and chromosomal aberrations, as well as fewer camptothecin (CPT)-induced RAD51 foci in subject-derived cell lines. Importantly, these cellular defects were rescued upon re-expression of wild-type (WT) TONSL; this rescue is consistent with the hypothesis that hypomorphic TONSL variants are pathogenic. Overall, our studies in humans, mice, zebrafish, and subject-derived cell lines confirm that pathogenic variants in TONSL impair DNA replication and homologous recombination-dependent repair processes, and they lead to a spectrum of skeletal dysplasia phenotypes with numerous extra-skeletal manifestations.


Assuntos
Instabilidade Cromossômica , Dano ao DNA , Variação Genética , Anormalidades Musculoesqueléticas/patologia , NF-kappa B/genética , Osteocondrodisplasias/patologia , Adolescente , Adulto , Alelos , Animais , Células Cultivadas , Criança , Pré-Escolar , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Estudos de Associação Genética , Humanos , Camundongos , Camundongos Knockout , Anormalidades Musculoesqueléticas/genética , Osteocondrodisplasias/genética , Sequenciamento Completo do Exoma , Adulto Jovem , Peixe-Zebra
15.
Genet Med ; 21(2): 275-283, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-29970925

RESUMO

PURPOSE: Osteogenesis imperfecta (OI) predisposes people to recurrent fractures, bone deformities, and short stature. There is a lack of large-scale systematic studies that have investigated growth parameters in OI. METHODS: Using data from the Linked Clinical Research Centers, we compared height, growth velocity, weight, and body mass index (BMI) in 552 individuals with OI. Height, weight, and BMI were plotted on Centers for Disease Control and Prevention normative curves. RESULTS: In children, the median z-scores for height in OI types I, III, and IV were -0.66, -6.91, and -2.79, respectively. Growth velocity was diminished in OI types III and IV. The median z-score for weight in children with OI type III was -4.55. The median z-scores for BMI in children with OI types I, III, and IV were 0.10, 0.91, and 0.67, respectively. Generalized linear model analyses demonstrated that the height z-score was positively correlated with the severity of the OI subtype (P < 0.001), age, bisphosphonate use, and rodding (P < 0.05). CONCLUSION: From the largest cohort of individuals with OI, we provide median values for height, weight, and BMI z-scores that can aid the evaluation of overall growth in the clinic setting. This study is an important first step in the generation of OI-specific growth curves.


Assuntos
Estatura/fisiologia , Peso Corporal/fisiologia , Osteogênese Imperfeita/epidemiologia , Adolescente , Adulto , Índice de Massa Corporal , Criança , Pré-Escolar , Difosfonatos/uso terapêutico , Feminino , Humanos , Masculino , América do Norte , Osteogênese Imperfeita/tratamento farmacológico , Osteogênese Imperfeita/fisiopatologia , Pamidronato/uso terapêutico , Adulto Jovem
16.
Genet Med ; 21(7): 1652-1656, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30568308

RESUMO

PURPOSE: Brain malformations caused by 17p13.3 deletions include lissencephaly with deletions of the larger Miller-Dieker syndrome region or smaller deletions of only PAFAH1B1, white matter changes, and a distinct syndrome due to deletions including YWHAE and CRK but sparing PAFAH1B1. We sought to understand the significance of 17p13.3 deletions between the YWHAE/CRK and PAFAH1B1 loci. METHODS: We analyzed the clinical features of six individuals from five families with 17p13.3 deletions between and not including YWHAE/CRK and PAFAH1B1 identified among individuals undergoing clinical chromosomal microarray testing or research genome sequencing. RESULTS: Five individuals from four families had multifocal white matter lesions while a sixth had a normal magnetic resonance image. A combination of our individuals and a review of those in the literature with white matter changes and deletions in this chromosomal region narrows the overlapping region for this brain phenotype to ~345 kb, including 11 RefSeq genes, with RTN4RL1 haploinsufficiency as the best candidate for causing this phenotype. CONCLUSION: While previous literature has hypothesized dysmorphic features and white matter changes related to YWHAE, our cohort contributes evidence to the presence of additional genetic changes within 17p13.3 required for proper brain development.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 17 , Leucoencefalopatias/genética , 1-Alquil-2-acetilglicerofosfocolina Esterase/genética , Proteínas 14-3-3/genética , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Recém-Nascido , Leucoencefalopatias/diagnóstico por imagem , Imagem por Ressonância Magnética , Masculino , Proteínas Associadas aos Microtúbulos/genética
17.
Am J Hum Genet ; 103(6): 1030-1037, 2018 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-30503518

RESUMO

FUK encodes fucokinase, the only enzyme capable of converting L-fucose to fucose-1-phosphate, which will ultimately be used for synthesizing GDP-fucose, the donor substrate for all fucosyltransferases. Although it is essential for fucose salvage, this pathway is thought to make only a minor contribution to the total amount of GDP-fucose. A second pathway, the major de novo pathway, involves conversion of GDP-mannose to GDP-fucose. Here we describe two unrelated individuals who have pathogenic variants in FUK and who presented with severe developmental delays, encephalopathy, intractable seizures, and hypotonia. The first individual was compound heterozygous for c.667T>C (p.Ser223Pro) and c.2047C>T (p.Arg683Cys), and the second individual was homozygous for c.2980A>C (p.Lys994Gln). Skin fibroblasts from the first individual confirmed the variants as loss of function and showed significant decreases in total GDP-[3H] fucose and [3H] fucose-1-phosphate. There was also a decrease in the incorporation of [5,6-3H]-fucose into fucosylated glycoproteins. Lys994 has previously been shown to be an important site for ubiquitin conjugation. Here, we show that loss-of-function variants in FUK cause a congenital glycosylation disorder characterized by a defective fucose-salvage pathway.


Assuntos
Anormalidades Congênitas/genética , Variação Genética/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Sequência de Aminoácidos , Encefalopatias/genética , Criança , Deficiências do Desenvolvimento/genética , Feminino , Fibroblastos/patologia , Fucosiltransferases/genética , Glicosilação , Guanosina Difosfato Fucose/genética , Guanosina Difosfato Manose/genética , Humanos , Masculino , Hipotonia Muscular/genética , Convulsões/genética , Alinhamento de Sequência , Pele/patologia , Ubiquitina/genética
18.
JBMR Plus ; 2(4): 235-239, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30283904

RESUMO

The heritable disorder osteogenesis imperfecta (OI) is characterized by bone fragility and low bone mass. OI type VI is an autosomal recessive form of the disorder with moderate to severe bone fragility. OI type VI is caused by mutations in the serpin peptidase inhibitor, clade F, member 1 (SERPINF1), the gene coding for pigment epithelium-derived factor (PEDF). Here, we report a patient with OI type VI caused by a novel homozygous intronic variant in SERPINF1 identified by whole-exome sequencing (WES). The mutation was not identified using a low bone mass gene panel based on next-generation sequencing. This variant creates a novel consensus splice donor site (AGGC to AGGT) in intron 4. Analysis of cDNA generated from fibroblasts revealed retention of a 32-bp intronic fragment between exons 4 and 5 in the cDNA, a result of alternative splicing from the novel splice-donor site. As a result, the aberrant insertion of this intronic fragment generated a frameshift pathogenic variant and induced nonsense-mediated decay. Furthermore, gene expression by quantitative PCR showed SERPINF1 expression was dramatically reduced in patient fibroblasts, and PEDF level was also significantly reduced in the patient's plasma. In conclusion, we report a novel homozygous variant that generates an alternative splice-donor in intron 4 of SERPINF1 which gives rise to severe bone fragility. The work also demonstrates clinical utility of WES analysis, and consideration of noncoding variants, in the diagnostic setting of rare bone diseases. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

20.
Am J Hum Genet ; 102(6): 1126-1142, 2018 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-29805043

RESUMO

The proteasome processes proteins to facilitate immune recognition and host defense. When inherently defective, it can lead to aberrant immunity resulting in a dysregulated response that can cause autoimmunity and/or autoinflammation. Biallelic or digenic loss-of-function variants in some of the proteasome subunits have been described as causing a primary immunodeficiency disease that manifests as a severe dysregulatory syndrome: chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE). Proteasome maturation protein (POMP) is a chaperone for proteasome assembly and is critical for the incorporation of catalytic subunits into the proteasome. Here, we characterize and describe POMP-related autoinflammation and immune dysregulation disease (PRAID) discovered in two unrelated individuals with a unique constellation of early-onset combined immunodeficiency, inflammatory neutrophilic dermatosis, and autoimmunity. We also begin to delineate a complex genetic mechanism whereby de novo heterozygous frameshift variants in the penultimate exon of POMP escape nonsense-mediated mRNA decay (NMD) and result in a truncated protein that perturbs proteasome assembly by a dominant-negative mechanism. To our knowledge, this mechanism has not been reported in any primary immunodeficiencies, autoinflammatory syndromes, or autoimmune diseases. Here, we define a unique hypo- and hyper-immune phenotype and report an immune dysregulation syndrome caused by frameshift mutations that escape NMD.


Assuntos
Predisposição Genética para Doença , Chaperonas Moleculares/genética , Mutação/genética , Degradação do RNAm Mediada por Códon sem Sentido/genética , Sequência de Bases , Linhagem Celular , Estresse do Retículo Endoplasmático , Éxons/genética , Família , Mutação da Fase de Leitura/genética , Heterozigoto , Humanos , Síndromes de Imunodeficiência/genética , Imunofenotipagem , Recém-Nascido , Inflamação/patologia , Interferon Tipo I/metabolismo , Masculino , Proteínas Mutantes/metabolismo , Fenótipo , Complexo de Endopeptidases do Proteassoma/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Síndrome , Resposta a Proteínas não Dobradas
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