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SpliceAI is an open-source deep learning splicing prediction algorithm that has demonstrated in the past few years its high ability to predict splicing defects caused by DNA variations. However, its outputs present several drawbacks: (1) although the numerical values are very convenient for batch filtering, their precise interpretation can be difficult, (2) the outputs are delta scores which can sometimes mask a severe consequence, and (3) complex delins are most often not handled. We present here SpliceAI-visual, a free online tool based on the SpliceAI algorithm, and show how it complements the traditional SpliceAI analysis. First, SpliceAI-visual manipulates raw scores and not delta scores, as the latter can be misleading in certain circumstances. Second, the outcome of SpliceAI-visual is user-friendly thanks to the graphical presentation. Third, SpliceAI-visual is currently one of the only SpliceAI-derived implementations able to annotate complex variants (e.g., complex delins). We report here the benefits of using SpliceAI-visual and demonstrate its relevance in the assessment/modulation of the PVS1 classification criteria. We also show how SpliceAI-visual can elucidate several complex splicing defects taken from the literature but also from unpublished cases. SpliceAI-visual is available as a Google Colab notebook and has also been fully integrated in a free online variant interpretation tool, MobiDetails ( https://mobidetails.iurc.montp.inserm.fr/MD ). Graphical abstract

Marfan syndrome (MFS) is a rare autosomal dominant connective tissue disorder related to variants in the FBN1 gene. Prognosis is related to aortic risk of dissection following aneurysm. MFS clinical variability is notable, for age of onset as well as severity and number of clinical manifestations. To identify genetic modifiers, we combined genome-wide approaches in 1070 clinically well-characterized FBN1 disease-causing variant carriers: (1) an FBN1 eQTL analysis in 80 fibroblasts of FBN1 stop variant carriers, (2) a linkage analysis, (3) a kinship matrix association study in 14 clinically concordant and discordant sib-pairs, (4) a genome-wide association study and (5) a whole exome sequencing in 98 extreme phenotype samples.Three genetic mechanisms of variability were found. A new genotype/phenotype correlation with an excess of loss-of-cysteine variants (P = 0.004) in severely affected subjects. A second pathogenic event in another thoracic aortic aneurysm gene or the COL4A1 gene (known to be involved in cerebral aneurysm) was found in nine individuals. A polygenic model involving at least nine modifier loci (named gMod-M1-9) was observed through cross-mapping of results. Notably, gMod-M2 which co-localizes with PRKG1, in which activating variants have already been described in thoracic aortic aneurysm, and gMod-M3 co-localized with a metalloprotease (proteins of extra-cellular matrix regulation) cluster. Our results represent a major advance in understanding the complex genetic architecture of MFS and provide the first steps toward prediction of clinical evolution.

Genetic generalized epilepsy (GGE) including childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy (JME), and GGE with tonic–clonic seizures (TCS) (GGE-TCS), is genetically influenced with a two- to four- fold increased risk in the first-degree relatives of patients. Since large families with GGE are very rare, international studies have focused on sporadic GGE patients using whole exome sequencing, suggesting that GGE are highly genetically heterogeneous and rather involve rare or ultra-rare variants. Moreover, a polygenic mode of inheritance is suspected in most cases. We performed SNP microarrays and whole exome sequencing in 20 families from Sudan, focusing on those with at least four affected members. Standard genetic filters and Endeavour algorithm for functional prioritization of genes selected likely susceptibility variants in FAT1, DCHS1 or ASTN2 genes. FAT1 and DCHS1 are adhesion transmembrane proteins interacting during brain development, while ASTN2 is involved in dendrite development. Our approach on familial forms of GGE is complementary to large-scale collaborative consortia studies of sporadic cases. Our study reinforces the hypothesis that GGE is genetically heterogeneous, even in a relatively limited geographic area, and mainly oligogenic, as supported by the low familial penetrance of GGE and by the Bayesian algorithm that we developed in a large pedigree with JME. Since populations with founder effect and endogamy are appropriate to study autosomal recessive pathologies, they would be also adapted to decipher genetic components of complex diseases, using the reported bayesian model. Graphical Abstract

The number of genes associated with autism is increasing, but few studies have been performed on epidemiological cohorts and in isolated populations. Here, we investigated 357 individuals from the Faroe Islands including 36 individuals with autism, 136 of their relatives and 185 non-autism controls. Data from SNP array and whole exome sequencing revealed that individuals with autism had a higher burden of rare exonic copy-number variants altering autism associated genes (deletions (p = 0.0352) or duplications (p = 0.0352)), higher inbreeding status (p = 0.023) and a higher load of rare homozygous deleterious variants (p = 0.011) compared to controls. Our analysis supports the role of several genes/loci associated with autism (e.g., NRXN1, ADNP, 22q11 deletion) and identified new truncating (e.g., GRIK2, ROBO1, NINL, and IMMP2L) or recessive deleterious variants (e.g., KIRREL3 and CNTNAP2) affecting autism-associated genes. It also revealed three genes involved in synaptic plasticity, RIMS4, KALRN, and PLA2G4A, carrying de novo deleterious variants in individuals with autism without intellectual disability. In summary, our analysis provides a better understanding of the genetic architecture of autism in isolated populations by highlighting the role of both common and rare gene variants and pointing at new autism-risk genes. It also indicates that more knowledge about how multiple genetic hits affect neuronal function will be necessary to fully understand the genetic architecture of autism.Genetic correlates of autism in natives of remote islandsA study of the genetic architecture of autism among people living on the remote Faroe Islands highlights the role of both common and rare gene variants to autism. Claire Leblond from the Institut Pasteur in Paris, France, and colleagues profiled the genetics of 357 Faroese individuals, including 36 with autism, 136 of their relatives and 185 non-autistic controls. Similar to the findings of genetic studies of autism from elsewhere, the researchers discovered rare structural variants in known autism-associated genes and a few new candidate genes linked to brain function. However, unlike studies from larger mainland populations, they also showed that inbreeding on these remote islands increased the likelihood of carrying two copies of the point mutations that contribute to autism.

Desmin is a class III intermediate filament protein highly expressed in cardiac, smooth and striated muscle. Autosomal dominant or recessive mutations in the desmin gene (DES) result in a variety of diseases, including cardiomyopathies and myofibrillar myopathy, collectively called desminopathies. Here we describe the clinical, histological and radiological features of a Greek patient with a myofibrillar myopathy and cardiomyopathy linked to the c.734A>G,p.(Glu245Gly) heterozygous variant in the DES gene. Moreover, through ribonucleic acid sequencing analysis in skeletal muscle we show that this variant provokes a defect in exon 3 splicing and thus should be considered clearly pathogenic.

ADNP is a well-known gene implicated in intellectual disability and its molecular spectrum consists mainly in loss of function variant in the ADNP last and largest exon. Here, we report the first description of a patient with intellectual disability identified with an intragenic inversion in ADNP. RNAseq experiment showed a splice skipping of the inversed exons. Moreover, in-silico analysis of initiating ATGs in the mutated transcript using contextual Kozak score suggested that several initiating ATGs were likely used to translate poisonous out-of-frame ORFs and would lead to the suppression of any in-frame rescuing translation, thereby causing haploinsufficiency. As constitutive Alu sequences with high homology were identified at both breakpoints in reversed orientation in the reference genome, we hypothesized that Alu-mediated non-allelic-homologous recombination was responsible for this rearrangement. Therefore, as this inversion is not detectable by exome sequencing, this mechanism could be a potential underdiagnosed recurrent mutation in ADNP-related disorders.

Purpose Abnormality of the corpus callosum (AbnCC) is etiologically a heterogeneous condition and the prognosis in prenatally diagnosed cases is difficult to predict. The purpose of our research was to establish the diagnostic yield using chromosomal microarray (CMA) and exome sequencing (ES) in cases with prenatally diagnosed isolated (iAbnCC) and nonisolated AbnCC (niAbnCC). Methods CMA and prenatal trio ES (pES) were done on 65 fetuses with iAbnCC and niAbnCC. Only pathogenic gene variants known to be associated with AbnCC and/or intellectual disability were considered. Results pES results were available within a median of 21.5 days (9–53 days). A pathogenic single-nucleotide variant (SNV) was identified in 12 cases (18%) and a pathogenic CNV was identified in 3 cases (4.5%). Thus, the genetic etiology was determined in 23% of cases. In all diagnosed cases, the results provided sufficient information regarding the neurodevelopmental prognosis and helped the parents to make an informed decision regarding the outcome of the pregnancy. Conclusion Our results show the significant diagnostic and prognostic contribution of CMA and pES in cases with prenatally diagnosed AbnCC. Further prospective cohort studies with long-term follow-up of the born children will be needed to provide accurate prenatal counseling after a negative pES result.

Biallelic variants in the ERLIN1 gene were recently reported as the cause of two motor neuron degeneration diseases, SPG62 and a recessive form of amyotrophic lateral sclerosis. However, only 12 individuals from five pedigrees have been identified so far. Thus, the description of the disease remains limited. Following the discovery of a homozygous pathogenic variant in a girl with SPG62, presenting with intellectual disability, and epilepsy, we gathered the largest series of SPG62 cases reported so far (13 individuals) to better understand the phenotype associated with ERLIN1. We collected molecular and clinical data for 13 individuals from six families with ERLIN1 biallelic variants. We performed RNA-seq analyses to characterize intronic variants and used Alphafold and a transcripts database to characterize the molecular consequences of the variants. We identified three new variants suspected to alter the bell-shaped ring formed by the ERLIN1/ERLIN2 complex. Affected individuals had childhood-onset paraparesis with slow progression. Six individuals presented with gait ataxia and three had superficial sensory loss. Aside from our proband, none had intellectual disability or epilepsy. Biallelic pathogenic ERLIN1 variants induce a rare, predominantly pure, spastic paraparesis, with possible cerebellar and peripheral nerve involvement.

BackgroundUbiquitination has a central role in numerous biological processes, including cell development, stress responses and ageing. Perturbed ubiquitination has been implicated in human diseases ranging from cancer to neurodegenerative diseases. SIAH1 encodes a RING-type E3 ubiquitin ligase involved in protein ubiquitination. Among numerous other roles, SIAH1 regulates metabotropic glutamate receptor signalling and affects neural cell fate. Moreover, SIAH1 positively regulates Wnt signalling through ubiquitin-mediated degradation of Axin and accumulation of β-catenin.MethodsTrio exome sequencing followed by Sanger validation was undertaken in five individuals with syndromic developmental delay. Three-dimensional structural modelling was used to predict pathogenicity of affected residues. Wnt stimulatory activity was measured by luciferase reporter assays and Axin degradation assays in HEK293 cells transfected with wild-type and mutant SIAH1 expression plasmids.ResultsWe report five unrelated individuals with shared features of developmental delay, infantile hypotonia, dysmorphic features and laryngomalacia, in whom exome sequencing identified de novo monoallelic variants in SIAH1. In silico protein modelling suggested alteration of conserved functional sites. In vitro experiments demonstrated loss of Wnt stimulatory activity with the SIAH1 mutants, suggesting variant pathogenicity.ConclusionOur results lend support to SIAH1 as a candidate Mendelian disease gene for a recognisable syndrome, further strengthening the connection between SIAH1 and neurodevelopmental disorders. Furthermore, the results suggest that dysregulation of the Wnt/β-catenin pathway may be involved in the pathogenesis.

De novo missense variants in KCNH1 encoding Kv10.1 are responsible for two clinically recognisable phenotypes: Temple-Baraitser syndrome (TBS) and Zimmermann-Laband syndrome (ZLS). The clinical overlap between these two syndromes suggests that they belong to a spectrum of KCNH1-related encephalopathies. Affected patients have severe intellectual disability (ID) with or without epilepsy, hypertrichosis and distinctive features such as gingival hyperplasia and nail hypoplasia/aplasia (present in 20/23 reported cases).We report a series of seven patients with ID and de novo pathogenic KCNH1 variants identified by whole-exome sequencing or an epilepsy gene panel in whom the diagnosis of TBS/ZLS had not been first considered. Four of these variants, p.(Thr294Met), p.(Ala492Asp), p.(Thr493Asn) and p.(Gly496Arg), were located in the transmembrane domains S3 and S6 of Kv10.1 and one, p.(Arg693Gln), in its C-terminal cyclic nucleotide-binding homology domain (CNBHD). Clinical reappraisal by the referring clinical geneticists confirmed the absence of the distinctive gingival and nail features of TBS/ZLS.Our study expands the phenotypical spectrum of KCNH1-related encephalopathies to individuals with an attenuated extraneurological phenotype preventing a clinical diagnosis of TBS or ZLS. This subtype may be related to recurrent substitutions of the Gly496, suggesting a genotype–phenotype correlation and, possibly, to variants in the CNBHD domain.