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1.
Am J Hum Genet ; 105(3): 640-657, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31402090

RESUMO

The identification of genetic variants implicated in human developmental disorders has been revolutionized by second-generation sequencing combined with international pooling of cases. Here, we describe seven individuals who have diverse yet overlapping developmental anomalies, and who all have de novo missense FBXW11 variants identified by whole exome or whole genome sequencing and not reported in the gnomAD database. Their phenotypes include striking neurodevelopmental, digital, jaw, and eye anomalies, and in one individual, features resembling Noonan syndrome, a condition caused by dysregulated RAS signaling. FBXW11 encodes an F-box protein, part of the Skp1-cullin-F-box (SCF) ubiquitin ligase complex, involved in ubiquitination and proteasomal degradation and thus fundamental to many protein regulatory processes. FBXW11 targets include ß-catenin and GLI transcription factors, key mediators of Wnt and Hh signaling, respectively, critical to digital, neurological, and eye development. Structural analyses indicate affected residues cluster at the surface of the loops of the substrate-binding domain of FBXW11, and the variants are predicted to destabilize the protein and/or its interactions. In situ hybridization studies on human and zebrafish embryonic tissues demonstrate FBXW11 is expressed in the developing eye, brain, mandibular processes, and limb buds or pectoral fins. Knockdown of the zebrafish FBXW11 orthologs fbxw11a and fbxw11b resulted in embryos with smaller, misshapen, and underdeveloped eyes and abnormal jaw and pectoral fin development. Our findings support the role of FBXW11 in multiple developmental processes, including those involving the brain, eye, digits, and jaw.

2.
Pain ; 2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31408049

RESUMO

Hereditary sensory and autonomic neuropathies (HSANs) are a group of clinically and genetically heterogeneous disorders of the peripheral nervous system mainly characterized by impaired nociception and autonomic dysfunction. We previously identified heme metabolism as a novel pathway contributing to sensory neurons maintenance and nociception. Indeed, we reported mutations in the Feline Leukemia Virus subgroup C Receptor 1 (FLVCR1) gene in individuals affected by HSAN. FLVCR1 gene encodes for 2 heme export proteins, FLVCR1a (plasma membrane) and FLVCR1b (mitochondria), crucially involved in the regulation of cellular heme homeostasis. Here, we report on 2 additional patients carrying novel biallelic mutations in FLVCR1 translation initiation codon (c.2T>C; p.(Met1Thr) and c.3G>T; p.(Met1Ile)). We overexpressed the c.2T>C; p.(Met1Thr) mutant in human cell lines and we describe its impact on protein structure and function in comparison with other HSAN-related mutations. We found that the mutation interferes with translation in 2 different ways: by lowering levels of translation of wild-type protein and by inducing translation initiation from a downstream in-frame ATG, leading to the production of an N-terminal truncated protein that is retained in the endoplasmic reticulum. The impact of different kinds of mutations on FLVCR1a localization and structure was also described. The identification of novel FLVCR1 mutations in HSAN reinforces the crucial role of heme in sensory neuron maintenance and pain perception. Moreover, our in vitro findings demonstrate that heme export is not completely lost in HSAN patients, thus suggesting the possibility to improve FLVCR1 expression/activity for therapeutic purposes.

3.
Clin Genet ; 96(2): 169-175, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31066025

RESUMO

Heterozygous missense variants in the SPTBN2 gene, encoding the non-erythrocytic beta spectrin 2 subunit (beta-III spectrin), have been identified in autosomal dominant spinocerebellar ataxia type 5 (SCA5), a rare adult-onset neurodegenerative disorder characterized by progressive cerebellar ataxia, whereas homozygous loss of function variants in SPTBN2 have been associated with early onset cerebellar ataxia and global developmental delay (SCAR14). Recently, heterozygous SPTBN2 missense variants have been identified in a few patients with an early-onset ataxic phenotype. We report five patients with non-progressive congenital ataxia and psychomotor delay, 4/5 harboring novel heterozygous missense variants in SPTBN2 and one patient with compound heterozygous SPTBN2 variants. With an overall prevalence of 5% in our cohort of unrelated patients screened by targeted next-generation sequencing (NGS) for congenital or early-onset cerebellar ataxia, this study indicates that both dominant and recessive mutations of SPTBN2 together with CACNA1A and ITPR1, are a frequent cause of early-onset/congenital non-progressive ataxia and that their screening should be implemented in this subgroup of disorders.

4.
Hum Mutat ; 40(5): 601-618, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30801875

RESUMO

Mitochondria are highly dynamic organelles, undergoing continuous fission and fusion. The DNM1L (dynamin-1 like) gene encodes for the DRP1 protein, an evolutionary conserved member of the dynamin family, responsible for fission of mitochondria, and having a role in the division of peroxisomes, as well. DRP1 impairment is implicated in several neurological disorders and associated with either de novo dominant or compound heterozygous mutations. In five patients presenting with severe epileptic encephalopathy, we identified five de novo dominant DNM1L variants, the pathogenicity of which was validated in a yeast model. Fluorescence microscopy revealed abnormally elongated mitochondria and aberrant peroxisomes in mutant fibroblasts, indicating impaired fission of these organelles. Moreover, a very peculiar finding in our cohort of patients was the presence, in muscle biopsy, of core like areas with oxidative enzyme alterations, suggesting an abnormal distribution of mitochondria in the muscle tissue.

5.
BMC Med Genet ; 19(1): 196, 2018 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-30419932

RESUMO

BACKGROUND: IARS2 encodes a mitochondrial isoleucyl-tRNA synthetase, a highly conserved nuclear-encoded enzyme required for the charging of tRNAs with their cognate amino acid for translation. Recently, pathogenic IARS2 variants have been identified in a number of patients presenting broad clinical phenotypes with autosomal recessive inheritance. These phenotypes range from Leigh and West syndrome to a new syndrome abbreviated CAGSSS that is characterised by cataracts, growth hormone deficiency, sensory neuropathy, sensorineural hearing loss, and skeletal dysplasia, as well as cataract with no additional anomalies. METHODS: Genomic DNA from Iranian probands from two families with consanguineous parental background and overlapping CAGSSS features were subjected to exome sequencing and bioinformatics analysis. RESULTS: Exome sequencing and data analysis revealed a novel homozygous missense variant (c.2625C > T, p.Pro909Ser, NM_018060.3) within a 14.3 Mb run of homozygosity in proband 1 and a novel homozygous missense variant (c.2282A > G, p.His761Arg) residing in an ~ 8 Mb region of homozygosity in a proband of the second family. Patient-derived fibroblasts from proband 1 showed normal respiratory chain enzyme activity, as well as unchanged oxidative phosphorylation protein subunits and IARS2 levels. Homology modelling of the known and novel amino acid residue substitutions in IARS2 provided insight into the possible consequence of these variants on function and structure of the protein. CONCLUSIONS: This study further expands the phenotypic spectrum of IARS2 pathogenic variants to include two patients (patients 2 and 3) with cataract and skeletal dysplasia and no other features of CAGSSS to the possible presentation of the defects in IARS2. Additionally, this study suggests that adult patients with CAGSSS may manifest central adrenal insufficiency and type II esophageal achalasia and proposes that a variable sensorineural hearing loss onset, proportionate short stature, polyneuropathy, and mild dysmorphic features are possible, as seen in patient 1. Our findings support that even though biallelic IARS2 pathogenic variants can result in a distinctive, clinically recognisable phenotype in humans, it can also show a wide range of clinical presentation from severe pediatric neurological disorders of Leigh and West syndrome to both non-syndromic cataract and cataract accompanied by skeletal dysplasia.

6.
Hum Mol Genet ; 2018 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-30481304

RESUMO

Noonan syndrome (NS), the most common RASopathy, is caused by mutations affecting signaling through RAS and the MAPK cascade. Recently, genome scanning has discovered novel genes implicated in NS, whose function in RAS-MAPK signaling remains obscure, suggesting the existence of unrecognized circuits contributing to signal modulation in this pathway. Among these genes, LZTR1 encodes a functionally poorly characterized member of the BTB/POZ protein superfamily. Two classes of germline LZTR1 mutations underlie dominant and recessive forms of NS, while constitutional monoallelic, mostly inactivating, mutations in the same gene cause schwannomatosis, a cancer-prone disorder clinically distinct from NS. Here we show that dominant NS-causing LZTR1 mutations do not affect significantly protein stability and subcellular localization. We provide the first evidence that these mutations, but not the missense changes occurring as biallelic mutations in recessive NS, enhance stimulus-dependent RAS-MAPK signaling, which is triggered, at least in part, by an increased RAS protein pool. Moreover, we document that dominant NS-causing mutations do not perturb binding of LZTR1 to CUL3, a scaffold coordinating the assembly of a multimeric complex catalyzing protein ubiquitination, but are predicted to affect the surface of the Kelch domain mediating substrate binding to the complex. Collectively, our data suggest a model in which LZTR1 contributes to the ubiquitination of protein(s) functioning as positive modulator(s) of the RAS-MAPK signaling pathway. In this model, LZTR1 mutations are predicted to variably impair binding of these substrates to the multi-component ligase complex and their efficient ubiquitination and degradation, resulting in MAPK signaling upregulation.

7.
J Med Genet ; 55(12): 837-846, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30323018

RESUMO

BACKGROUND: Wiedemann-Rautenstrauch syndrome (WRS) is a form of segmental progeria presenting neonatally, characterised by growth retardation, sparse scalp hair, generalised lipodystrophy with characteristic local fatty tissue accumulations and unusual face. We aimed to understand its molecular cause. METHODS: We performed exome sequencing in two families, targeted sequencing in 10 other families and performed in silico modelling studies and transcript processing analyses to explore the structural and functional consequences of the identified variants. RESULTS: Biallelic POLR3A variants were identified in eight affected individuals and monoallelic variants of the same gene in four other individuals. In the latter, lack of genetic material precluded further analyses. Multiple variants were found to affect POLR3A transcript processing and were mostly located in deep intronic regions, making clinical suspicion fundamental to detection. While biallelic POLR3A variants have been previously reported in 4H syndrome and adolescent-onset progressive spastic ataxia, recurrent haplotypes specifically occurring in individuals with WRS were detected. All WRS-associated POLR3A amino acid changes were predicted to perturb substantially POLR3A structure/function. CONCLUSION: Biallelic mutations in POLR3A, which encodes for the largest subunit of the DNA-dependent RNA polymerase III, underlie WRS. No isolated functional sites in POLR3A explain the phenotype variability in POLR3A-related disorders. We suggest that specific combinations of compound heterozygous variants must be present to cause the WRS phenotype. Our findings expand the molecular mechanisms contributing to progeroid disorders.

8.
Clin Genet ; 2018 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-30288735

RESUMO

Biallelic exostosin-2 (EXT2) pathogenic variants have been described as the cause of the Seizures-Scoliosis-Macrocephaly syndrome (OMIM 616682) characterized by intellectual disability, facial dysmorphisms and seizures. More recently, it has been proposed to rename this disorder with the acronym AREXT2 (autosomal recessive EXT2-related syndrome). Here, we report the third family affected by AREXT2 syndrome, harboring compound missense variants in EXT2, p.Asp227Asn, and p.Tyr608Cys. In addition, our patients developed multiple exostoses, which were not observed in the previously described families. AREXT2 syndrome can be considered as a multiorgan Congenital Disorder of Glycosylation caused by a significant, but non-lethal, decrease in EXT2 expression, thereby affecting the synthesis of the heparan sulfate proteoglycans, which is relevant in many physiological processes. Our finding expands the clinical and molecular spectrum of the AREXT2 syndrome and suggests a possible genotype/phenotype correlation in the development of the exostoses.

9.
Horm Res Paediatr ; 90(3): 203-211, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30179867

RESUMO

BACKGROUND: The development of gonadotropin-independent (peripheral) precocious puberty in male children with primary adrenal insufficiency (PAI) is consistent with a defect in the genes encoding for the enzymes involved in steroid hormone biosynthesis. METHODS: Two young boys presented with peripheral precocious puberty followed by PAI. In both patients, the analysis of CYP21A2 gene encoding 21-hydroxylase was normal. As a second step, a targeted next-generation sequencing (NGS) was performed in both patients using a customized panel of congenital endocrine disor ders. RESULTS: Case 1 had a new homozygous variant in the CYP11B1 gene (c.1121+5G>A). Mutations of this gene cause congenital adrenal hyperplasia due to 11ß-hydroxylase deficiency, an essential enzyme in the cortisol biosynthesis pathway. Case 2 showed a new hemizygous mutation in the NR0B1 gene (c.1091T>G), which encodes for DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia congenita [AHC] and critical region on the X chromosome gene 1). NR0B1 mutations cause X-linked AHC and hypogonadotropic hypogonadism. Pathogenicity prediction software defined both mutations as probably damaging. CONCLUSIONS: Peripheral precocious puberty was the atypical presentation of 2 rare genetic diseases. The use of NGS made the characterization of these 2 cases with similar clinical phenotypes caused by 2 different genetic defects possible.

10.
Front Immunol ; 9: 1835, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30150985

RESUMO

Autoimmune-poly-endocrinopathy-candidiasis-ectodermal-dystrophy syndrome (APECED) is a rare monogenic recessive disorder caused by mutations in the autoimmune regulator (AIRE) gene. Criteria for the diagnosis of APECED are the presence of two of the following disorders: chronic mucocutaneous candidiasis (CMC), chronic hypoparathyroidism (CHP), and Addison's disease. APECED develops at high incidence in Finns, Sardinians, and Iranian Jews and presents with a wide range of clinical phenotypes and genotypes. In this manuscript, we report the clinical, endocrinological, and molecular features of a 16-year-old female patient from Pakistan living in Italy and presenting the major APECED clinical manifestations CMC, CHP, and primary adrenal insufficiency. Premature ovarian failure, chronic bronchopneumopathy, vitiligo, Hashimoto's thyroiditis emerged as associated diseases. In our patient, AIRE gene screening revealed the novel c.396G>C (p.Arg132Ser; p.R132S) mutation in homozygosity thus confirming APECED diagnosis. This is the first reported mutation within the nuclear localization signal (NLS) that is associated with APECED. The NLS mutation affects the nuclear import of classical transcription factors through nuclear pore by recognition of nuclear import receptors, the importin α molecules. By displaying crystal structures of the peptide containing the KRK basic residue cluster bound to α importins, we show that p.R132S replacement in 131-KRK-133 does not reproduce these interactions. Thus, we propose that the novel mutation exerts its pathogenetic effect by impairing the nuclear import of the Aire protein. The present case report is added to a limited series of Pakistani APECED patients who we reviewed from the scientific literature, mostly diagnosed on clinical findings.

11.
Orphanet J Rare Dis ; 13(1): 79, 2018 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-29769092

RESUMO

BACKGROUND: Alpha-1-antitrypsin (AAT) deficiency (AATD) of Z, Mmalton, Siiyama type is associated with liver storage of the mutant proteins and liver disease. The Z variant can be diagnosed on isoelectric focusing (IEF) while Mmalton and Siiyama may be missed or misdiagnosed with this technique. Therefore, molecular analysis is mandatory for their characterization. In particular, that holds true for the Mmalton variant as on IEF profile it resembles the wild M2 subtype. METHODS: This is a retrospective analysis involving review of medical records and of liver biopsy specimens from a series of Mmalton, Z and Siiyama Alpha-1-antitrypsin deficiency patients. The review has been implemented by additional histological stains, electron microscopic observations and 3-D modeling studies of the sites of the mutations. RESULTS: Z, Mmalton and Siiyama liver specimen contained characteristic intrahepatocytic PAS-D globules. The globules differed in the three variants as only Mmalton cases showed dark basophilic precipitates within the AAT inclusions. The precipitates were visualized in haematoxylin-eosin (H.E.) stained preparations and corresponded to calcium precipitates as demonstrated by von Kossa staining. On immunohistochemistry, ZAAT inclusions were stained by polyclonal as well as monoclonal noncommercial anti-AAT antibody (AZT11), whilst Mmalton and Siiyama inclusion bodies remained negative with the monoclonal anti-Z antibody. 3-D protein analysis allowed to predict more severe misfolding of the Mmalton molecule as compared to Z and Siiyama that could trigger anomalous interaction with endoplasmic reticulum chaperon proteins, namely calcium binding proteins. CONCLUSIONS: Mmalton AAT inclusion bodies contain calcium precipitates inside them that allow the differential diagnosis with Siiyama and ZAAT inclusions in routine histological sections. The study has confirmed the specificity of the monoclonal AZT11 for the Z mutant. Thus, the combination of these two features is crucial for the distinction between the three variants and for predicting the genotype, whose confirmation would definitely require molecular analysis. Our study provides new data on the pathomorphogenesis of Mmalton inclusion bodies whose mineralization could play a central role in disease pathogenesis of Mmalton that is distinct from the Z and Siiyama variants. Calcium is known to be a major effector of cell death either via the increased intracellular concentration or the alteration of homeostasis.

12.
Hum Mol Genet ; 27(11): 1892-1904, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29547997

RESUMO

Microtubules participate in fundamental cellular processes, including chromosomal segregation and cell division, migration and intracellular trafficking. Their proper function is required for correct central nervous system development and operative preservation, and mutations in genes coding tubulins, the constituting units of microtubules, underlie a family of neurodevelopmental and neurodegenerative diseases, collectively known as 'tubulinopathies', characterized by a wide range of neuronal defects resulting from defective proliferation, migration and function. Here, we causally link a previously unreported missense mutation in TUBB2A (c.1249G>A, p.D417N), encoding one of the neuron-specific ß-tubulin isotype II, to a disorder characterized by progressive spastic paraplegia, peripheral sensory-motor polyneuropathy and ataxia. Asp417 is a highly conserved solvent-exposed residue at the site mediating binding of kinesin superfamily motors. Impaired binding to KIF1A, a neuron-specific kinesin required for transport of synaptic vesicle precursors of the disease-associated TUBB2A mutant, was predicted by structural analyses and confirmed experimentally in vitro. We show that overexpression of TUBB2AD417N disrupts the mitotic spindle bipolarity and morphology and affects the M phase entry and length. Differently from the TUBB2AN247K and TUBB2AA248V, two mutants previously identified to affect neurodevelopment, TUBB2AD417N retains the ability to assemble into microtubules. Consistent with the differential clinical and structural impact, TUBB2AA248V does not drastically affect TUBB2A binding to KIF1A, nor mitotic spindle bipolarity. Overall, our data demonstrate a pathogenic role of the p.D417N substitution that is different from previously reported TUBB2A mutations and expand the phenotypic spectrum associated with mutations in this gene.

13.
Mol Genet Genomic Med ; 6(3): 446-451, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29500860

RESUMO

BACKGROUND: Fowler syndrome is a rare autosomal recessive disorder characterized by hydranencephaly-hydrocephaly and multiple pterygium due to fetal akinesia. To date, around 45 cases from 27 families have been reported, and the pathogenic bi-allelic mutations in FLVCR2 gene described in 15 families. The pathogenesis of this condition has not been fully elucidated so far. METHODS: We report on an additional family with two affected fetuses carrying a novel homozygous mutation in FLVCR2 gene, and describe the impact of known mutants on the protein structural and functional impairment. RESULTS: The present report confirms the genetic homogeneity of Fowler syndrome and describes a new FLVCR2 mutation affecting the protein function. The structural analysis of the present and previously published FLVCR2 mutations supports the hypothesis of a reduced heme import as the underlying disease's mechanism due to the stabilization of the occluded conformation or a protein misfolding. CONCLUSION: Our data suggest the hypothesis of heme deficiency as the major pathogenic mechanism of Fowler syndrome.


Assuntos
Hidranencefalia/genética , Proteínas de Membrana Transportadoras/genética , Receptores Virais/genética , Alelos , Sequência de Aminoácidos/genética , Feto/patologia , Heme/genética , Heme/metabolismo , Humanos , Hidranencefalia/fisiopatologia , Hidrocefalia/genética , Proteínas de Membrana Transportadoras/fisiologia , Mutação , Receptores Virais/fisiologia , Doenças Vasculares/genética
14.
Cerebellum ; 17(4): 499-503, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29476442

RESUMO

Mutations in KCNJ10, which encodes the inwardly rectifying potassium channel Kir4.1, a primary regulator of membrane excitability and potassium homeostasis, cause a complex syndrome characterized by seizures, sensorineural deafness, ataxia, intellectual disability, and electrolyte imbalance called SeSAME/EAST syndrome. We describe a 41-year-old patient with non-syndromic, slowly progressive, early-onset ataxia. Targeted next-generation sequencing identified a novel c.180 T > G (p.Ile60Met) missense homozygous mutation. The mutated residue Ile60Met likely impairs phosphatidylinositol 4, 5-bisphosphate (PIP2) binding which is known to play an essential role in channel gating. Our study expands the clinical and mutational spectrum of KCNJ10-related disorders and suggests that screening of this gene should be implemented in patients with early-onset ataxia, with or without syndromic features.

15.
Hum Mutat ; 39(4): 563-578, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29314548

RESUMO

In recent years, an increasing number of mitochondrial disorders have been associated with mutations in mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs), which are key enzymes of mitochondrial protein synthesis. Bi-allelic functional variants in VARS2, encoding the mitochondrial valyl tRNA-synthetase, were first reported in a patient with psychomotor delay and epilepsia partialis continua associated with an oxidative phosphorylation (OXPHOS) Complex I defect, before being described in a patient with a neonatal form of encephalocardiomyopathy. Here we provide a detailed genetic, clinical, and biochemical description of 13 patients, from nine unrelated families, harboring VARS2 mutations. All patients except one, who manifested with a less severe disease course, presented at birth exhibiting severe encephalomyopathy and cardiomyopathy. Features included hypotonia, psychomotor delay, seizures, feeding difficulty, abnormal cranial MRI, and elevated lactate. The biochemical phenotype comprised a combined Complex I and Complex IV OXPHOS defect in muscle, with patient fibroblasts displaying normal OXPHOS activity. Homology modeling supported the pathogenicity of VARS2 missense variants. The detailed description of this cohort further delineates our understanding of the clinical presentation associated with pathogenic VARS2 variants and we recommend that this gene should be considered in early-onset mitochondrial encephalomyopathies or encephalocardiomyopathies.

16.
Int J Mol Sci ; 18(12)2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-29244742

RESUMO

p.R375W (Fibrinogen Aguadilla) is one out of seven identified mutations (Brescia, Aguadilla, Angers, Al du Pont, Pisa, Beograd, and Ankara) causing hepatic storage of the mutant fibrinogen γ. The Aguadilla mutation has been reported in children from the Caribbean, Europe, Japan, Saudi Arabia, Turkey, and China. All reported children presented with a variable degree of histologically proven chronic liver disease and low plasma fibrinogen levels. In addition, one Japanese and one Turkish child had concomitant hypo-APOB-lipoproteinemia of unknown origin. We report here on an additional child from Turkey with hypofibrinogenemia due to the Aguadilla mutation, massive hepatic storage of the mutant protein, and severe hypo-APOB-lipoproteinemia. The liver biopsy of the patient was studied by light microscopy, electron microscopy (EM), and immunohistochemistry. The investigation included the DNA sequencing of the three fibrinogen and APOB-lipoprotein regulatory genes and the analysis of the encoded protein structures. Six additional Fibrinogen Storage Disease (FSD) patients with either the Aguadilla, Ankara, or Brescia mutations were investigated with the same methodology. A molecular analysis revealed the fibrinogen gamma p.R375W mutation (Aguadilla) but no changes in the APOB and MTTP genes. APOB and MTTP genes showed no abnormalities in the other study cases. Light microscopy and EM studies of liver tissue samples from the child led to the demonstration of the simultaneous accumulation of both fibrinogen and APOB in the same inclusions. Interestingly enough, APOB-containing lipid droplets were entrapped within the fibrinogen inclusions in the hepatocytic Endoplasmic Reticulum (ER). Similar histological, immunohistochemical, EM, and molecular genetics findings were found in the other six FSD cases associated with the Aguadilla, as well as with the Ankara and Brescia mutations. The simultaneous retention of fibrinogen and APOB-lipoproteins in FSD can be detected in routinely stained histological sections. The analysis of protein structures unraveled the pathomorphogenesis of this unexpected phenomenon. Fibrinogen gamma chain mutations provoke conformational changes in the region of the globular domain involved in the "end-to-end" interaction, thus impairing the D-dimer formation. Each monomeric fibrinogen gamma chain is left with an abnormal exposure of hydrophobic patches that become available for interactions with APOB and lipids, causing their intracellular retention and impairment of export as a secondary unavoidable phenomenon.


Assuntos
Afibrinogenemia/genética , Apolipoproteína B-100/genética , Fibrinogênio/genética , Hipolipoproteinemias/genética , Hepatopatias/sangue , Afibrinogenemia/sangue , Afibrinogenemia/patologia , Apolipoproteína B-100/sangue , Pré-Escolar , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Feminino , Fibrinogênio/química , Fibrinogênio/metabolismo , Hepatócitos/química , Hepatócitos/metabolismo , Hepatócitos/patologia , Humanos , Hipolipoproteinemias/metabolismo , Hipolipoproteinemias/patologia , Fígado/metabolismo , Fígado/patologia , Hepatopatias/genética , Hepatopatias/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Conformação Proteica , Relação Estrutura-Atividade
17.
Arch. argent. pediatr ; 115(6): 440-444, dic. 2017. ilus, tab
Artigo em Espanhol | LILACS-Express | ID: biblio-887410

RESUMO

La displasia cleidocraneal es una displasia ósea infrecuente con patrón de herencia autosómico dominante, que se caracteriza por presentar talla baja, fontanelas amplias, hipoplasia mediofacial, ausencia o hipoplasia de clavículas y alteraciones orodentales. Es producida por mutaciones en el gen RUNX2 localizado en 6p21.1. Se presentan dos adolescentes masculinos (primos hermanos) con displasia cleidocraneal, los cuales mostraron mutación heterocigota, cambio de sentido (c.674G>A, p.R225Q) en el gen RUNX2, caracterizados por presentar fenotipo grave, como ausencia de clavículas, pero con variación en el retardo en el cierre de fontanelas, alteraciones dentales (anomalías en forma y número) y escoliosis, por lo que se demuestra la variación intrafamiliar en estos pacientes con el mismo genotipo.


Cleidocranial dysplasia is an uncommon bone dysplasia with an autosomal dominant inheritance pattern characterized by short stature, large fontanels, midface hypoplasia, absence or hypoplasia of clavicles and orodental alterations. This is produced by mutations in the RUNX2 gene located at 6p21.1. We report two male adolescents (cousins), with cleidocranial dysplasia who presented a heterozygous missense mutation (c.674G> A, p.R225Q) in the RUNX2 gene, characterized by severe phenotype, such as absent clavicles, but with variation in the delayed fontanel closure, dental abnormalities (anomalies in shape and number) and scoliosis, thus demonstrating intrafamilial variation in these patients with the same genotype.

18.
Arch Argent Pediatr ; 115(6): e440-e444, 2017 Dec 01.
Artigo em Espanhol | MEDLINE | ID: mdl-29087131

RESUMO

Cleidocranial dysplasia is an uncommon bone dysplasia with an autosomal dominant inheritance pattern characterized by short stature, large fontanels, midface hypoplasia, absence or hypoplasia of clavicles and orodental alterations. This is Estudio clínico y molecular en una familia con displasia cleidocraneal Clinical and molecular study in a family with cleidocranial dysplasia produced by mutations in the RUNX2 gene located at 6p21.1. We report two male adolescents (cousins), with cleidocranial dysplasia who presented a heterozygous missense mutation (c.674G> A, p.R225Q) in the RUNX2 gene, characterized by severe phenotype, such as absent clavicles, but with variation in the delayed fontanel closure, dental abnormalities (anomalies in shape and number) and scoliosis, thus demonstrating intrafamilial variation in these patients with the same genotype.


Assuntos
Displasia Cleidocraniana/genética , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Adolescente , Displasia Cleidocraniana/diagnóstico , Displasia Cleidocraniana/diagnóstico por imagem , Humanos , Masculino , Linhagem , Fenótipo
19.
Ital J Pediatr ; 43(1): 65, 2017 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-28768552

RESUMO

BACKGROUND: Adenylosuccinate lyase (ADSL) deficiency is a defect of purine metabolism affecting purinosome assembly and reducing metabolite fluxes through purine de novo synthesis and purine nucleotide recycling pathways. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The most severe form is characterized by neonatal encephalopathy, absence of spontaneous movement, respiratory failure, intractable seizures, and early death within the first weeks of life. More commonly, ADSL presents purely neurologic clinical picture characterized by severe psychomotor retardation, microcephaly, early onset of seizures, and autistic features (type I) or a more slowly progressing form with later onset, and major features including slight to moderate psychomotor retardation, and transient contact disturbances (type II). Diagnostic markers are the presence of succinylaminoimidazole carboxamide riboside (SAICAr) and succinyladenosine (SAdo) in extracellular fluids. ADSL is a rare disorder, although its prevalence remains unknown. Of note, the wide range of essentially nonspecific manifestations and lack of awareness of the condition often prevent diagnosis. CASE PRESENTATION: We present here the case of particularly mild, late onset ADSL that has been unsuccessfully investigated until whole exome sequencing (WES) was performed. CONCLUSIONS: Besides emphasizing the valuable diagnostic value of WES, this report provides new data further documenting the relatively wide clinical manifestation of ADSL.


Assuntos
Adenilossuccinato Liase/deficiência , Transtorno Autístico/diagnóstico por imagem , Transtorno Autístico/genética , Deficiências do Desenvolvimento/genética , Imagem por Ressonância Magnética/métodos , Erros Inatos do Metabolismo da Purina-Pirimidina/diagnóstico por imagem , Erros Inatos do Metabolismo da Purina-Pirimidina/genética , Adenilossuccinato Liase/genética , Criança , Deficiências do Desenvolvimento/diagnóstico por imagem , Deficiências do Desenvolvimento/patologia , Epilepsia/diagnóstico , Epilepsia/etiologia , Feminino , Seguimentos , Humanos , Doenças Raras , Índice de Gravidade de Doença , Sequenciamento Completo do Exoma
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