Approximately 15 % of PD patients with Parkinson Disease (PD) have the familial type and 5–10 % of these are known to have monogenic forms with either an autosomal dominant or a recessive inheritance ...pattern. Here, we report on a family carrying the A53T SNCA mutation and we review SNCA mutation phenotypes by comparing point mutations within each other as well as with duplication and triplication.
Acrofrontofacionasal Dysostosis type 1 (AFFND1) is an extremely rare, autosomal recessive syndrome, comprising facial and skeletal abnormalities, short stature and intellectual disability. We ...analyzed an Indian family with two affected siblings by exome sequencing and identified a novel homozygous truncating mutation in the Neuroblastoma-Amplified Sequence (NBAS) gene in the patients' genome. Mutations in the NBAS gene have recently been associated with different phenotypes mainly involving skeletal formation, liver and cognitive development. The NBAS protein has been implicated in two key cellular processes, namely the non-sense mediated decay and the Golgi-to-Endoplasmic Reticulum retrograde traffic. Both functions were impaired in HEK293T cells overexpressing the truncated NBAS protein, as assessed by Real-Time PCR, Western blot analysis, co-immunoprecipitation, and immunofluorescence analysis. We examined the expression of NBAS protein in mouse embryos at various developmental stages by immunohistochemistry, and detected expression in developing chondrogenic and osteogenic structures of the skeleton as well as in the cortex, hippocampus and cerebellum, which is compatible with a role in bone and brain development. Functional genetics in the zebrafish model showed that depletion of endogenous z-nbas in fish embryos results in defective morphogenesis of chondrogenic cranial skeletal elements. Overall, our data point to a conserved function of NBAS in skeletal morphogenesis during development, support the hypothesis of a causative role of the mutated NBAS gene in the pathogenesis of AFFND1 and extend the spectrum of phenotypes associated with defects in this gene.
•AFFND1 is a very rare syndrome with skeletal abnormalities and intellectual disability likely due to a developmental defect•In two AFFND1 Indian siblings we found a novel homozygous mutation in the NBAS gene•In overexpression studies the putative mutant NBAS protein had impaired function in NMD pathway and Golgi-to-ER transport•NBAS is expressed in mouse embryos in diverse skeletal compartments which are affected by the disease in patients•NBAS knockdown in zebrafish embryos causes abnormal skeletal phenotypes and altered gene expression•Overall, these data are in agreement with a role of NBAS mutation in AFFND1 pathogenesis in this family
Lafora disease is a rare recessive form of progressive myoclonic epilepsy, usually diagnosed during adolescence. Patients present with myoclonus, neurological deterioration, and generalized ...tonic-clonic, myoclonic, or absence seizures. Symptoms worsen until death, usually within the first ten years of clinical onset. The primary histopathological hallmark is the formation of aberrant polyglucosan aggregates called Lafora bodies in the brain and other tissues. Lafora disease is caused by mutations in either the EPM2A gene, encoding laforin, or the EPM2B gene, coding for malin. The most frequent EPM2A mutation is R241X, which is also the most prevalent in Spain. The Epm2a‐/− and Epm2b−/− mouse models of Lafora disease show neuropathological and behavioral abnormalities similar to those seen in patients, although with a milder phenotype. To obtain a more accurate animal model, we generated the Epm2aR240X knock-in mouse line with the R240X mutation in the Epm2a gene, using genetic engineering based on CRISPR-Cas9 technology. Epm2aR240X mice exhibit most of the alterations reported in patients, including the presence of LBs, neurodegeneration, neuroinflammation, interictal spikes, neuronal hyperexcitability, and cognitive decline, despite the absence of motor impairments. The Epm2aR240X knock-in mouse displays some symptoms that are more severe that those observed in the Epm2a−/− knock-out, including earlier and more pronounced memory loss, increased levels of neuroinflammation, more interictal spikes and increased neuronal hyperexcitability, symptoms that more precisely resemble those observed in patients. This new mouse model can therefore be specifically used to evaluate how new therapies affects these features with greater precision.
Display omitted
•When compared to Epm2a−/− mice, Epm2aR240X knock-in mice.•Present earlier cognitive decline.•More neuroinflammation and epileptic activity.•Similar number of Lafora bodies and neurodegeneration.•The Epm2aR240X mouse appears to be a better model to study some aspects of the disease.
Spinocerebellar ataxia 17 (SCA17) is a rare genetic cause of adult-onset ataxia caused by an abnormal expansion of the CAG/CAA sequence in the TATA-box Binding Protein (
TBP)
gene. A number of ...repeats higher than 49 are full penetrance-expanded. The range between 41 and 49 repeats is characterized by decreased penetrance, and it is usually referred to as “small.” Here, we describe two patients with the SCA17 phenotype and with 43 and 44 CAG repeats in the TBP gene, and review all the previously reported cases of SCA17 with a small range of expansions. We focus on both clinical features and imaging findings, which, in the case of small-expanded alleles, can resemble those of atypical parkinsonisms. Thus, we suggest to consider the small-expanded allele SCA17 as a possible diagnosis in patients with adult-onset ataxia, even when both clinical and imaging characteristics are suggestive for other non-genetic neurodegenerative diseases.
The pathogenesis of moyamoya disease (MMD) is still unknown. The detection of inflammatory molecules such as cytokines, chemokines and growth factors in MMD patients' biological fluids supports the ...hypothesis that an abnormal angiogenesis is implicated in MMD pathogenesis. However, it is unclear whether these anomalies are the consequences of the disease or rather causal factors as well as these mechanisms remain insufficient to explain the pathophysiology of MMD. The presence of a family history in about 9-15% of Asian patients, the highly variable incidence rate between different ethnic and sex groups and the age of onset support the role of genetic factors in MMD pathogenesis. However, although some genetic loci have been associated with MMD, few of them have been replicated in independent series. Recently, RNF213 gene was shown to be strongly associated with MMD occurrence with a founder effect in East Asian patients. However, the mechanisms leading from RNF213 mutations to MMD clinical features are still unknown.
The research on pathogenic mechanism of MMD is in its infancy. MMD is probably a complex and heterogeneous disorder, including different phenotypes and genotypes, in which more than a single factor is implicated.
Since the diagnosis of MMD is rapidly increasing worldwide, the development of more efficient stratifying risk systems, including both clinical but also biological drivers became imperative to improve our ability of predict prognosis and to develop mechanism-tailored interventions.
Context:
The pathogenesis of congenital hypothyroidism (CH) is still largely unexplained. We previously reported that perturbations of the Notch pathway and knockdown of the ligand jagged1 cause a ...hypothyroid phenotype in the zebrafish. Heterozygous JAG1 variants are known to account for Alagille syndrome type 1 (ALGS1), a rare multisystemic developmental disorder characterized by variable expressivity and penetrance.
Objective:
Verify the involvement of JAG1 variants in the pathogenesis of congenital thyroid defects and the frequency of unexplained hypothyroidism in a series of ALGS1 patients.
Design, Settings, and Patients:
A total of 21 young ALGS1 and 100 CH unrelated patients were recruited in academic and public hospitals. The JAG1 variants were studied in vitro and in the zebrafish.
Results:
We report a previously unknown nonautoimmune hypothyroidism in 6/21 ALGS1 patients, 2 of them with thyroid hypoplasia. We found 2 JAG1 variants in the heterozygous state in 4/100 CH cases (3 with thyroid dysgenesis, 2 with cardiac malformations). Five out 7 JAG1 variants are new. Different bioassays demonstrate that the identified variants exhibit a variable loss of function. In zebrafish, the knock-down of jag1a/b expression causes a primary thyroid defect, and rescue experiments of the hypothyroid phenotype with wild-type or variant JAG1 transcripts support a role for JAG1 variations in the pathogenesis of the hypothyroid phenotype seen in CH and ALGS1 patients.
Conclusions:
clinical and experimental data indicate that ALGS1 patients have an increased risk of nonautoimmune hypothyroidism, and that variations in JAG1 gene can contribute to the pathogenesis of variable congenital thyroid defects, including CH.
Given the crucial role of the personalized management and treatment of hearing loss (HL), etiological investigations are performed early on, and genetic analysis significantly contributes to the ...determination of most syndromic and nonsyndromic HL cases. Knowing hundreds of syndromic associations with HL, little comprehensive data about HL in genomic disorders due to microdeletion or microduplications of contiguous genes is available. Together with the description of a new patient with a novel 3.7 Mb deletion of the Xq21 critical locus, we propose an unreported literature review about clinical findings in patients and their family members with Xq21 deletion syndrome. We finally propose a comprehensive review of HL in contiguous gene syndromes in order to confirm the role of cytogenomic microarray analysis to investigate the etiology of unexplained HL.
The 22q11.2 deletion syndrome (22q11.2DS) is the most common genomic disorder in humans and is the result of a recurrent 1.5 to 2.5 Mb deletion, encompassing approximately 20–40 genes, respectively. ...The clinical presentation of the typical deletion includes: Velocardiofacial, Di George, Opitz G/BBB and Conotruncalanomaly face syndromes. Atypical deletions (proximal, distal or nested) are rare and characterized mainly by normal phenotype or mild intellectual disability and variable clinical features. The pathogenetic mechanisms underlying this disorder are not completely understood. Because the 22q11.2 region harbours genes coding for transcriptional factors and chromatin remodelers, in this study, we performed analysis of genome-wide DNA methylation of peripheral blood from 49 patients with 22q11.2DS using the Illumina Infinium Methylation EPIC bead chip arrays. This cohort comprises 43 typical, 2 proximal and 4 distal deletions. We demonstrated the evidence of a unique and highly specific episignature in all typical and proximal 22q11.2DS. The sensitivity and specificity of this signature was further confirmed by comparing it to over 1500 patients with other neurodevelopmental disorders with known episignatures. Mapping the 22q11.2DS DNA methylation episignature provides both novel insights into the molecular pathogenesis of this disorder and an effective tool in the molecular diagnosis of 22q11.2DS.
Oculo-auriculo-vertebral-spectrum (OAVS; OMIM 164210) is a rare disorder originating from abnormal development of the first and second branchial arch. The clinical phenotype is extremely ...heterogeneous with ear anomalies, hemifacial microsomia, ocular defects, and vertebral malformations being the main features.
,
, and
gene variants were reported in a few OAVS patients, but the etiology remains largely unknown. A multifactorial origin has been proposed, including the involvement of environmental and epigenetic mechanisms. To identify the epigenetic mechanisms contributing to OAVS, we evaluated the DNA-methylation profiles of 41 OAVS unrelated affected individuals by using a genome-wide microarray-based methylation approach. The analysis was first carried out comparing OAVS patients with controls at the group level. It revealed a moderate epigenetic variation in a large number of genes implicated in basic chromatin dynamics such as DNA packaging and protein-DNA organization. The alternative analysis in individual profiles based on the searching for Stochastic Epigenetic Variants (SEV) identified an increased number of SEVs in OAVS patients compared to controls. Although no recurrent deregulated enriched regions were found, isolated patients harboring suggestive epigenetic deregulations were identified. The recognition of a different DNA methylation pattern in the OAVS cohort and the identification of isolated patients with suggestive epigenetic variations provide consistent evidence for the contribution of epigenetic mechanisms to the etiology of this complex and heterogeneous disorder.
Malformations of the cerebral cortex are an important cause of developmental disabilities and epilepsy. Neurological disorders caused by abnormal neuronal migration have been observed to occur with ...mutations in tubulin genes. The α- and β-tubulin genes encode cytoskeletal proteins, which play a role in the developing brain. TUBA1A mutations are associated with a wide spectrum of neurological problems, which are characterized by peculiar clinical details and neuroradiologic patterns. This manuscript describes the case of a nine-year-old girl with microcephaly, mild facial dysmorphisms, epileptic seizures, and severe developmental delay, with a de novo heterozygous c.320A>G p.(His 107 Arg) mutation in
gene, and the clinical aspects and neuroimaging features of "lissencephaly syndrome" are summarized. This case shows that
mutations lead to a variety of brain malformations ranging from lissencephaly with perisylvian pachygyria to diffuse posteriorly predominant pachygyria, combined with internal capsule dysgenesis, cerebellar dysplasia, and callosal hypotrophy. This peculiar neuroradiological pattern, in combination with the usually severe clinical presentation, suggests the need for future molecular studies to address the mechanisms of
mutation-induced neuropathology.
PDF
