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Strabismus is a common condition, affecting 1-4% of individuals. Isolated strabismus has been studied in families with Mendelian inheritance patterns. Despite the identification of multiple loci via linkage analyses, no specific genes have been identified from these studies. The current study is based on a seven-generation family with isolated strabismus inherited in an autosomal dominant manner. A total of 13 individuals from a common ancestor have been included for linkage analysis, and a single linkage signal has been identified at chromosome 14q12 with a multipoint LOD score of 4.69. Disruption of this locus is known to cause FOXG1 syndrome (or congenital Rett syndrome; OMIM #613454 and *164874), in which 84% of affected individuals present with strabismus. With the incorporation of next generation sequencing and in-depth bioinformatic analyses, a 4bp non-coding deletion was prioritized as the top candidate for the observed strabismus phenotype. The deletion is predicted to disrupt regulation of FOXG1, which encodes a transcription factor of the Forkhead family. Suggestive of an auto-regulation effect, the disrupted sequence matches the consensus FOXG1 and Forkhead family transcription factor binding site and has been observed in previous ChIP-seq studies to be bound by Foxg1 in early mouse brain development. The findings of this study indicate that the strabismus phenotype commonly observed within FOXG1 syndrome is separable from the more severe syndromic characteristics. Future study of this specific deletion may shed light on the regulation of FOXG1 expression and may enhance our understanding of the mechanisms contributing to strabismus and FOXG1 syndrome.Author summaryEye misalignment, or strabismus, can affect up to 4% of individuals. When strabismus is detected early, intervention in young children based on eye patching and/or corrective lenses can be beneficial. In some cases, corrective surgeries are used to align the eyes, with many individuals requiring multiple surgeries over a lifetime. A better understanding of the causes of strabismus may lead to earlier detection as well as improved treatment options. Hippocrates observed that strabismus runs in families over 2,400 years ago, an early recognition of what we now recognize as a portion of cases arising from genetic causes. We describe a large family affected by strabismus and identify a single region on chromosome 14 that may be responsible. The region contains FOXG1, in which mutations are known to cause a severe syndrome, with 84% of affected individuals also having strabismus. We identify a 4bp deletion in the region that appears to auto-regulate when FOXG1 is active. Future study of this genetic alteration may enhance our understanding of the mechanisms of strabismus.

Purpose The presentation and etiology of cerebral palsy (CP) are heterogeneous. Diagnostic evaluation can be a prolonged and expensive process that might remain inconclusive. This study aimed to determine the diagnostic yield and impact on management of next-generation sequencing (NGS) in 50 individuals with atypical CP (ACP). Methods Patient eligibility criteria included impaired motor function with onset at birth or within the first year of life, and one or more of the following: severe intellectual disability, progressive neurological deterioration, other abnormalities on neurological examination, multiorgan disease, congenital anomalies outside of the central nervous system, an abnormal neurotransmitter profile, family history, brain imaging findings not typical for cerebral palsy. Previous assessment by a neurologist and/or clinical geneticist, including biochemical testing, neuroimaging, and chromosomal microarray, did not yield an etiologic diagnosis. Results A precise molecular diagnosis was established in 65% of the 50 patients. We also identified candidate disease genes without a current OMIM disease designation. Targeted intervention was enabled in eight families (~15%). Conclusion NGS enabled a molecular diagnosis in ACP cases, ending the diagnostic odyssey, improving genetic counseling and personalized management, all in all enhancing precision medicine practices.

Here, we describe a fourth case of a human with a de novo KCNJ6 (GIRK2) mutation, who presented with clinical findings of severe hyperkinetic movement disorder and developmental delay, similar to the Keppen–Lubinsky syndrome but without lipodystrophy. Whole-exome sequencing of the patient’s DNA revealed a heterozygous de novo variant in the KCNJ6 (c.512T>G, p.Leu171Arg). We conducted in vitro functional studies to determine if this Leu-to-Arg mutation alters the function of GIRK2 channels. Heterologous expression of the mutant GIRK2 channel alone produced an aberrant basal inward current that lacked G protein activation, lost K+ selectivity and gained Ca2+ permeability. Notably, the inward current was inhibited by the Na+ channel blocker QX-314, similar to the previously reported weaver mutation in murine GIRK2. Expression of a tandem dimer containing GIRK1 and GIRK2(p.Leu171Arg) did not lead to any currents, suggesting heterotetramers are not functional. In neurons expressing p.Leu171Arg GIRK2 channels, these changes in channel properties would be expected to generate a sustained depolarization, instead of the normal G protein-gated inhibitory response, which could be mitigated by expression of other GIRK subunits. The identification of the p.Leu171Arg GIRK2 mutation potentially expands the Keppen–Lubinsky syndrome phenotype to include severe dystonia and ballismus. Our study suggests screening for dominant KCNJ6 mutations in the evaluation of patients with severe movement disorders, which could provide evidence to support a causal role of KCNJ6 in neurological channelopathies.

We describe neurotransmitter abnormalities in two patients with drug-resistant epilepsy resulting from deleterious de novo mutations in sodium channel genes. Whole exome sequencing identified a de novo SCN2A splice-site mutation (c.2379 +1G>A, p.G1u717Gly.fs*30) resulting in deletion of exon 14, in a 10-year old male with early onset global developmental delay, intermittent ataxia, autism, hypotonia, epileptic encephalopathy and cerebral/cerebellar atrophy. In the cerebrospinal fluid both homovanillic acid and 5-hydroxyindoleacetic acid were significantly decreased; extensive biochemical and genetic investigations ruled out primary neurotransmitter deficiencies and other known inborn errors of metabolism. In an 8-year old female with an early onset intractable epileptic encephalopathy, developmental regression, and progressive cerebellar atrophy, a previously unreported de novo missense mutation was identified in SCN8A (c.5615G>A; p.Arg1872GIn), affecting a highly conserved residue located in the C-terminal of the Na(v)1.6 protein. Aside from decreased homovanillic acid and 5-hydroxyindoleacetic acid, 5-methyltetrahydrofolate was also found to be low. We hypothesize that these channelopathies cause abnormal synaptic mono-amine metabolite secretion/uptake via impaired vesicular release and imbalance in electrochemical ion gradients, which in turn aggravate the seizures. Treatment with oral 5-hydroxytryptophan, L-Dopa/Carbidopa, and a dopa agonist resulted in mild improvement of seizure control in the male case, most likely via dopamine and serotonin receptor activated signal transduction and modulation of glutamatergic, GABA-ergic and glycinergic neurotransmission. Neurotransmitter analysis in other sodium channelopathy patients will help validate our findings, potentially yielding novel treatment opportunities. (C) 2015 Elsevier Inc. All rights reserved

RMND1 is an integral inner membrane mitochondrial protein that assembles into a large 240 kDa complex to support translation of the 13 polypeptides encoded on mtDNA, all of which are essential subunits of the oxidative phosphorylation (OXPHOS) complexes. Variants in RMND1 produce global defects in mitochondrial translation and were first reported in patients with severe neurological phenotypes leading to mortality in the first months of life. Using whole-exome sequencing, we identified compound heterozygous RMND1 variants in a 4-year-old patient with congenital lactic acidosis, severe myopathy, hearing loss, renal failure, and dysautonomia. The levels of mitochondrial ribosome proteins were reduced in patient fibroblasts, causing a translation defect, which was rescued by expression of the wild-type cDNA. RMND1 was almost undetectable by immunoblot analysis in patient muscle and fibroblasts. BN-PAGE analysis showed a severe combined OXPHOS assembly defect that was more prominent in patient muscle than in fibroblasts. Immunofluorescence experiments showed that RMND1 localizes to discrete foci in the mitochondrial network, juxtaposed to RNA granules where the primary mitochondrial transcripts are processed. RMND1 foci were not detected in patient fibroblasts. We hypothesize that RMND1 acts to anchor or stabilize the mitochondrial ribosome near the sites where the mRNAs are matured, spatially coupling post-transcriptional handling mRNAs with their translation, and that loss of function variants in RMND1 are associated with a unique constellation of clinical phenotypes that vary with the severity of the mitochondrial translation defect.

Background Dramatic improvements in DNA-sequencing technologies and computational analyses have led to wide use of whole exome sequencing (WES) to identify the genetic basis of Mendelian disorders. More than 180 novel rare-disease-causing genes with Mendelian inheritance patterns have been discovered through sequencing the exomes of just a few unrelated individuals or family members. As rare/novel genetic variants continue to be uncovered, there is a major challenge in distinguishing true pathogenic variants from rare benign mutations. Methods We used publicly available exome cohorts, together with the dbSNP database, to derive a list of genes (n = 100) that most frequently exhibit rare (

Graphical abstractDisplay Omitted First application of usability methods to evaluate exome analysis software.Key list of user desiderata on exome software from clinical geneticists is compiled.Identified usability challenges and design features for reengineering opportunities. ObjectivesNew DNA sequencing technologies have revolutionized the search for genetic disruptions. Targeted sequencing of all protein coding regions of the genome, called exome analysis, is actively used in research-oriented genetics clinics, with the transition to exomes as a standard procedure underway. This transition is challenging; identification of potentially causal mutation(s) amongst ~106 variants requires specialized computation in combination with expert assessment. This study analyzes the usability of user interfaces for clinical exome analysis software. There are two study objectives: (1) To ascertain the key features of successful user interfaces for clinical exome analysis software based on the perspective of expert clinical geneticists, (2) To assess user-system interactions in order to reveal strengths and weaknesses of existing software, inform future design, and accelerate the clinical uptake of exome analysis. MethodsSurveys, interviews, and cognitive task analysis were performed for the assessment of two next-generation exome sequence analysis software packages. The subjects included ten clinical geneticists who interacted with the software packages using the "think aloud" method. Subjects' interactions with the software were recorded in their clinical office within an urban research and teaching hospital. All major user interface events (from the user interactions with the packages) were time-stamped and annotated with coding categories to identify usability issues in order to characterize desired features and deficiencies in the user experience. ResultsWe detected 193 usability issues, the majority of which concern interface layout and navigation, and the resolution of reports. Our study highlights gaps in specific software features typical within exome analysis. The clinicians perform best when the flow of the system is structured into well-defined yet customizable layers for incorporation within the clinical workflow. The results highlight opportunities to dramatically accelerate clinician analysis and interpretation of patient genomic data. ConclusionWe present the first application of usability methods to evaluate software interfaces in the context of exome analysis. Our results highlight how the study of user responses can lead to identification of usability issues and challenges and reveal software reengineering opportunities for improving clinical next-generation sequencing analysis. While the evaluation focused on two distinctive software tools, the results are general and should inform active and future software development for genome analysis software. As large-scale genome analysis becomes increasingly common in healthcare, it is critical that efficient and effective software interfaces are provided to accelerate clinical adoption of the technology. Implications for improved design of such applications are discussed.

We describe a woman who presented with cataracts, optic atrophy, lipodystrophy/lipoatrophy, and peripheral neuropathy. Exome sequencing identified a c.235C > G p.(Leu79Val) variant in the optic atrophy 3 (OPA3) gene that was confirmed to be de novo. This report expands the severity of the phenotypic spectrum of autosomal dominant OPA3 mutations.

BACKGROUND: Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level.METHODS: To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient's clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes.RESULTS: We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%).CONCLUSIONS: Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children's Hospital Foundation and others.).

The Nrf2 (nuclear factor E2 p45-related factor 2) transcription factor responds to diverse oxidative and electrophilic environmental stresses by circumventing repression by Keap1, translocating to the nucleus, and activating cytoprotective genes. Nrf2 responses provide protection against chemical carcinogenesis, chronic inflammation, neurodegeneration, emphysema, asthma and sepsis in murine models. Nrf2 regulates the expression of a plethora of genes that detoxify oxidants and electrophiles and repair or remove damaged macromolecules, such as through proteasomal processing. However, many direct targets of Nrf2 remain undefined. Here, mouse embryonic fibroblasts (MEF) with either constitutive nuclear accumulation (Keap1(-/-)) or depletion (Nrf2(-/-)) of Nrf2 were utilized to perform chromatin-immunoprecipitation with parallel sequencing (ChIP-Seq) and global transcription profiling. This unique Nrf2 ChIP-Seq dataset is highly enriched for Nrf2-binding motifs. Integrating ChIP-Seq and microarray analyses, we identified 645 basal and 654 inducible direct targets of Nrf2, with 244 genes at the intersection. Modulated pathways in stress response and cell proliferation distinguish the inducible and basal programs. Results were confirmed in an in vivo stress model of cigarette smoke-exposed mice. This study reveals global circuitry of the Nrf2 stress response emphasizing Nrf2 as a central node in cell survival response.

International audience; JASPAR (http://jaspar.genereg.net) is an open-access database storing curated, non-redundant transcription factor (TF) binding profiles representing transcription factor binding preferences as position frequency matrices for multiple species in six taxonomic groups. For this 2016 release, we expanded the JASPAR CORE collection with 494 new TF binding profiles (315 in vertebrates, 11 in nematodes, 3 in insects, 1 in fungi and 164 in plants) and updated 59 profiles (58 in vertebrates and 1 in fungi). The introduced profiles represent an 83% expansion and 10% update when compared to the previous release. We updated the structural annotation of the TF DNA binding domains (DBDs) following a published hierarchical structural classification. In addition, we introduced 130 transcription factor flexible models trained on ChIP-seq data for vertebrates, which capture dinucleotide dependencies within TF binding sites. This new JASPAR release is accompanied by a new web tool to infer JASPAR TF binding profiles recognized by a given TF protein sequence. Moreover, we provide the users with a Ruby module complementing the JASPAR API to ease programmatic access and use of the JASPAR collection of profiles. Finally, we provide the JASPAR2016 R/Bioconductor data package with the data of this release.

Background: Phosphatidylinositol glycan biosynthesis class A protein (PIGA) is one of the enzymes involved in the biosynthesis of glycosylphosphatidylinositol (GPI) anchor proteins, which function as enzymes, adhesion molecules, complement regulators and co-receptors in signal transduction pathways. Until recently, only somatic PIGA mutations had been reported in patients with paroxysmal nocturnal hemoglobinuria (PNH), while germline mutations had not been observed, and were suspected to result in lethality. However, in just two years, whole exome sequencing (WES) analyses have identified germline PIGA mutations in male patients with XLIDD (X-linked intellectual developmental disorder) with a wide spectrum of clinical presentations. Methods and results: Here, we report on a new missense PIGA germline mutation [g.15342986C>T (p.S330N)] identified via WES followed by Sanger sequencing, in a Chinese male infant presenting with developmental arrest, infantile spasms, a pattern of lesion distribution on brain MRI resembling that typical of maple syrup urine disease, contractures, dysmorphism, elevated alkaline phosphatase, mixed hearing loss (a combination of conductive and sensorineural), liver dysfunction, mitochondrial complex I and V deficiency, and therapy-responsive dyslipidemia with confirmed lipoprotein lipase deficiency. X-inactivation studies showed skewing in the clinically unaffected carrier mother, and CD109 surface expression in patient fibroblasts was 57% of that measured in controls; together these data support pathogenicity of this mutation. Furthermore, we review all reported germline PIGA mutations (1 nonsense, 1 frameshift, 1 in-frame deletion, five missense) in 8 unrelated families. Conclusions: Our case further delineates the heterogeneous phenotype of this condition for which we propose the term 'PIGA deficiency'. While the phenotypic spectrum is wide, it could be classified into two types (severe and less severe) with shared hallmarks of infantile spasms with hypsarrhythmia on EEG and profound XLIDD. In severe PIGA deficiency, as described in our patient, patients also present with dysmorphic facial features, multiple CNS abnormalities, such as thin corpus callosum and delayed myelination, as well as hypotonia and elevated alkaline phosphatase along with liver, renal, and cardiac involvement; its course is often fatal. The less severe form of PIGA deficiency does not involve facial dysmorphism and multiple CNS abnormalities; instead, patients present with milder IDD, treatable seizures and generally a longer lifespan

Background The transition of whole-exome and whole-genome sequencing (WES/WGS) from the research setting to routine clinical practice remains challenging. Objectives With almost no previous research specifically assessing interface designs and functionalities of WES and WGS software tools, the authors set out to ascertain perspectives from healthcare professionals in distinct domains on optimal clinical genomics user interfaces. Methods A series of semi-scripted focus groups, structured around professional challenges encountered in clinical WES and WGS, were conducted with bioinformaticians (n = 8), clinical geneticists (n = 9), genetic counselors (n = 5), and general physicians (n = 4). Results Contrary to popular existing system designs, bioinformaticians preferred command line over graphical user interfaces for better software compatibility and customization flexibility. Clinical geneticists and genetic counselors desired an overarching interactive graphical layout to prioritize candidate variants—a “tiered” system where only functionalities relevant to the user domain are made accessible. They favored a system capable of retrieving consistent representations of external genetic information from third-party sources. To streamline collaboration and patient exchanges, the authors identified user requirements toward an automated reporting system capable of summarizing key evidence-based clinical findings among the vast array of technical details. Conclusions Successful adoption of a clinical WES/WGS system is heavily dependent on its ability to address the diverse necessities and predilections among specialists in distinct healthcare domains. Tailored software interfaces suitable for each group is likely more appropriate than the current popular “one size fits all” generic framework. This study provides interfaces for future intervention studies and software engineering opportunities.

Background: Cerebral palsy (CP) is a debilitating disorder (1). Based on neuromotor impairments it is divided to spastic, dyskinetic and ataxic types (2). Inborn Errors of Metabolism (IEMs), monogenic and chromosomal disorders mimic CP (3). We aimed to identify causal genetic variants in patients with atypical dyskinetic CP in whom known IEMs were ruled out. Timely diagnosis is essential for proper management, especially in conditions that mimic CP and are treatable. Methods: We enrolled 23 patients with unexplained atypical dyskinetic CP, for whole exome sequencing. Variants were filtered against public and in-house databases to identify variants predicted as damaging (in silico tools and ACMG criteria). We applied a virtual gene panel of known and suspected CP and movement disorder genes and investigated each sample. Results: The participants presented with symptoms including: spasticity, dystonia, choera-athetosis, ataxia and cognitive delays. We identified 23 diagnoses: 13 dominant,6 recessive and 4 X-linked. 12 patients had movement disorders. In 4, the diagnoses enabled targeted treatment (neurotransmitter supplements in Unverricht Lundborg diseases (CSTB) and PAK3 deficiency, deep brain stimulation in GNAO1 deficiency, medical diet in Glutaric Aciduria (GCDH). Conclusions: Whole Exome Sequencing contributes to establishing diagnosis in patients with atypical dyskinetic CP resulting in precision medicine and improved health outcomes.

Background: Dramatic improvements in DNA-sequencing technologies and computational analyses have led to wide use of whole exome sequencing (WES) to identify the genetic basis of Mendelian disorders. More than 180 novel rare-disease-causing genes with Mendelian inheritance patterns have been discovered through sequencing the exomes of just a few unrelated individuals or family members. As rare/novel genetic variants continue to be uncovered, there is a major challenge in distinguishing true pathogenic variants from rare benign mutations. Methods: We used publicly available exome cohorts, together with the dbSNP database, to derive a list of genes (n = 100) that most frequently exhibit rare (

Four children in three unrelated families (one consanguineous) presented with lethargy, hyperlactatemia, and hyperammonemia of unexplained origin during the neonatal period and early childhood. We identified and validated three different CA5A alterations, including a homozygous missense mutation (c.697T>C) in two siblings, a homozygous splice site mutation (c.555G>A) leading to skipping of exon 4, and a homozygous 4 kb deletion of exon 6. The deleterious nature of the homozygous mutation c.697T>C (p.Ser233Pro) was demonstrated by reduced enzymatic activity and increased temperature sensitivity. Carbonic anhydrase VA (CA-VA) was absent in liver in the child with the homozygous exon 6 deletion. The metabolite profiles in the affected individuals fit CA-VA deficiency, showing evidence of impaired provision of bicarbonate to the four enzymes that participate in key pathways in intermediary metabolism: carbamoylphosphate synthetase 1 (urea cycle), pyruvate carboxylase (anaplerosis, gluconeogenesis), propionyl-CoA carboxylase, and 3-methylcrotonyl-CoA carboxylase (branched chain amino acids catabolism). In the three children who were administered carglumic acid, hyperammonemia resolved. CA-VA deficiency should therefore be added to urea cycle defects, organic acidurias, and pyruvate carboxylase deficiency as a treatable condition in the differential diagnosis of hyperammonemia in the neonate and young child.

International audience; JASPAR (http://jaspar.genereg.net) is the largest open-access database of matrix-based nucleotide profiles describing the binding preference of transcription factors from multiple species. The fifth major release greatly expands the heart of JASPAR-the JASPAR CORE subcollection, which contains curated, non-redundant profiles-with 135 new curated profiles (74 in vertebrates, 8 in Drosophila melanogaster, 10 in Caenorhabditis elegans and 43 in Arabidopsis thaliana; a 30% increase in total) and 43 older updated profiles (36 in vertebrates, 3 in D. melanogaster and 4 in A. thaliana; a 9% update in total). The new and updated profiles are mainly derived from published chromatin immunoprecipitation-seq experimental datasets. In addition, the web interface has been enhanced with advanced capabilities in browsing, searching and subsetting. Finally, the new JASPAR release is accompanied by a new BioPython package, a new R tool package and a new R/Bioconductor data package to facilitate access for both manual and automated methods.

Distal hereditary motor neuropathies represent a group of rare genetic disorders characterized by progressive distal motor weakness without sensory loss. Their genetic heterogeneity is high and thus eligible for diagnostic whole exome sequencing. The authors report successful application of whole exome sequencing in diagnosing a second consanguineous family with distal hereditary motor neuropathy due to a homozygous c.151+1G>T variant in SIGMAR1. This variant was recently proposed as causal for the same condition in a consanguineous Chinese family. Compared to this family, the Afghan ethnic origin of our patient is distinct, yet the features are identical, validating the SIGMAR1 deficiency phenotype: progressive muscle wasting/weakness in lower and upper limbs without sensory loss. Rapid disease progression during adolescent growth is similar and may be due to SIGMAR1’s role in regulating axon elongation and tau phosphorylation. Finally, the authors conclude that SIGMAR1 deficiency should be added to the differential diagnosis of distal hereditary motor neuropathies.

Background: We undertook genetic analysis of three affected families to identify the cause of dominantly-inherited CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy and sensorineural hearing loss) syndrome. Methods We used whole-exome sequencing to analyze two families affected with CAPOS syndrome, including the original family reported in 1996, and Sanger sequencing to assess familial segregation of rare variants identified in the probands and in a third, apparently unrelated family with CAPOS syndrome. Results We found an identical heterozygous missense mutation, c.2452G > A (p.(Glu818Lys)), in the Na+/K+ ATPase α3 (ATP1A3) gene in the proband and his affected sister and mother, but not in either unaffected maternal grandparent, in the first family. The same mutation was also identified in the proband and three other affected members of the second family and in all three affected members of the third family. This mutation was not found in more than 3600 chromosomes from unaffected individuals. Conclusion Other mutations in ATP1A3 have previously been demonstrated to cause rapid-onset dystonia-parkinsonism (also called dystonia-12) or alternating hemiplegia of childhood. This study shows that an allelic mutation in ATP1A3 produces CAPOS syndrome.

Background: We report a 6.5 year-old female with a homozygous missense mutation in ZFYVE20, encoding Rabenosyn-5 (Rbsn-5), a highly conserved multi-domain protein implicated in receptor-mediated endocytosis. The clinical presentation includes intractable seizures, developmental delay, microcephaly, dysostosis, osteopenia, craniofacial dysmorphism, macrocytosis and megaloblastoid erythropoiesis. Biochemical findings include transient cobalamin deficiency, severe hypertriglyceridemia upon ketogenic diet, microalbuminuria and partial cathepsin D deficiency. Methods and results Whole exome sequencing followed by Sanger sequencing confirmed a rare (frequency:0.003987) homozygous missense mutation, g.15,116,371 G > A (c.1273G > A), in ZFYVE20 resulting in an amino acid change from Glycine to Arginine at position 425 of the Rbsn protein (p.Gly425Arg), as the only mutation segregating with disease in the family. Studies in fibroblasts revealed expression and localization of Rbsn-5G425R in wild-type manner, but a 50% decrease in transferrin accumulation, which is corrected by wild-type allele transfection. Furthermore, the patient’s fibroblasts displayed an impaired proliferation rate, cytoskeletal and lysosomal abnormalities. Conclusion These results are consistent with a functional defect in the early endocytic pathway resulting from mutation in Rbsn-5, which secondarily disrupts multiple cellular functions dependent on endocytosis, leading to a severe multi-organ disorder.

Background Fatty acid amide hydrolase 2 (FAAH2) is a hydrolase that mediates the degradation of endocannabinoids in man. Alterations in the endocannabinoid system are associated with a wide variety of neurologic and psychiatric conditions, but the phenotype and biochemical characterization of patients with genetic defects of FAAH2 activity have not previously been described. We report a male with autistic features with an onset before the age of 2 years who subsequently developed additional features including anxiety, pseudoseizures, ataxia, supranuclear gaze palsy, and isolated learning disabilities but was otherwise cognitively intact as an adult. Methods and results Whole exome sequencing identified a rare missense mutation in FAAH2, hg19: g.57475100G > T (c.1372G > T) resulting in an amino acid change (p.Ala458Ser), which was Sanger confirmed as maternally inherited and absent in his healthy brother. Alterations in lipid metabolism with abnormalities of the whole blood acyl carnitine profile were found. Biochemical and molecular modeling studies confirmed that the p.Ala458Ser mutation results in partial inactivation of FAAH2. Studies in patient derived fibroblasts confirmed a defect in FAAH2 activity resulting in altered levels of endocannabinoid metabolites. Conclusions We propose that genetic alterations in FAAH2 activity contribute to neurologic and psychiatric disorders in humans. Electronic supplementary material The online version of this article (doi:10.1186/s13023-015-0248-3) contains supplementary material, which is available to authorized users.

Stevens-Johnson syndrome (SJS) and drug-induced hypersensitivity syndrome (HSS, also known as DRESS) are life-threatening drug hypersensitivity reactions. Previous studies on genetic predictors for SJS and HSS were focused on immune-related genes and on known, frequent polymorphisms in the genome. For the anticonvulsant carbamazepine (CBZ), genetic markers for CBZ-induced SJS and HSS have been identified in the HLA region (HLA-B*15:02, HLA-A*31:01). However, many patients carriyng HLA-B*15:02 or HLA-A*31:01 tolerate CBZ, resulting in a low positive predictive value of a predictive test based on these genetic markers alone. In this pilot study, we aimed to identify rare genetic variants potentially associated with CBZ-induced SJS and HSS using whole exome sequencing in seven children with CBZ-induced SJS and five children with CBZ-induced HSS. Whole exome sequencing was performed using Illumina TruSeq exome capture and sequencing technology. Paired-end sequence reads were aligned and variants within 150 bp of the 64 Mb target region were identified using Bowtie, BWA and GATK. DNA samples from 95 CBZ-tolerant Canadian children were pooled and sequenced to a median depth of 300-fold to estimate frequencies of sequence variants identified in the hypersensitivity cases. All study participants were recruited through the Canadian Pharmacogenomics Network for Drug Safety. Children with CBZ-induced SJS or HSS were of European, Asian and First Nations ancestry with three SJS cases of Asian origin carrying HLA-B*15:02 and two HSS patients of European and First Nations origin carrying HLA-A*31:01. No individual rare single nucleotide variant (SNV) was strongly overrepresented in the SJS or HSS cases either in combined or in hypersensitivity reaction-specific analyses. Gene-based analyses revealed several candidate genes with rare nonsynonymous SNVs observed in a majority of SJS or HSS cases, respectively, which require follow-up in additional patients. With a hypothesis-free, comprehensive genetic screening approach, we identified new candidate genes and variants potentially involved in the development of CBZ-induced SJS or HSS for further investigation. The identified genes and pathways may lead to novel hypotheses for the pathomechanisms of these serious dermatologic reactions, potentially opening up new possibilities for prevention and treatment strategies.