TNPO2 variants associate with human developmental delays, neurologic deficits, and dysmorphic features and alter TNPO2 activity in Drosophila.

Transportin-2 (TNPO2) mediates multiple pathways including non-classical nucleocytoplasmic shuttling of >60 cargoes, such as developmental and neuronal proteins. We identified 15 individuals carrying de novo coding variants in TNPO2 who presented with global developmental delay (GDD), dysmorphic features, ophthalmologic abnormalities, and neurological features. To assess the nature of these variants, functional studies were performed in Drosophila. We found that fly dTnpo (orthologous to TNPO2) is expressed in a subset of neurons. dTnpo is critical for neuronal maintenance and function as downregulating dTnpo in mature neurons using RNAi disrupts neuronal activity and survival. Altering the activity and expression of dTnpo using mutant alleles or RNAi causes developmental defects, including eye and wing deformities and lethality. These effects are dosage dependent as more severe phenotypes are associated with stronger dTnpo loss. Interestingly, similar phenotypes are observed with dTnpo upregulation and ectopic expression of TNPO2, showing that loss and gain of Transportin activity causes developmental defects. Further, proband-associated variants can cause more or less severe developmental abnormalities compared to wild-type TNPO2 when ectopically expressed. The impact of the variants tested seems to correlate with their position within the protein. Specifically, those that fall within the RAN binding domain cause more severe toxicity and those in the acidic loop are less toxic. Variants within the cargo binding domain show tissue-dependent effects. In summary, dTnpo is an essential gene in flies during development and in neurons. Further, proband-associated de novo variants within TNPO2 disrupt the function of the encoded protein. Hence, TNPO2 variants are causative for neurodevelopmental abnormalities.

Loss-of-Function Variants in PPP1R12A: From Isolated Sex Reversal to Holoprosencephaly Spectrum and Urogenital Malformations.

In two independent ongoing next-generation sequencing projects for individuals with holoprosencephaly and individuals with disorders of sex development, and through international research collaboration, we identified twelve individuals with de novo loss-of-function (LoF) variants in protein phosphatase 1, regulatory subunit 12a (PPP1R12A), an important developmental gene involved in cell migration, adhesion, and morphogenesis. This gene has not been previously reported in association with human disease, and it has intolerance to LoF as illustrated by a very low observed-to-expected ratio of LoF variants in gnomAD. Of the twelve individuals, midline brain malformations were found in five, urogenital anomalies in nine, and a combination of both phenotypes in two. Other congenital anomalies identified included omphalocele, jejunal, and ileal atresia with aberrant mesenteric blood supply, and syndactyly. Six individuals had stop gain variants, five had a deletion or duplication resulting in a frameshift, and one had a canonical splice acceptor site loss. Murine and human in situ hybridization and immunostaining revealed PPP1R12A expression in the prosencephalic neural folds and protein localization in the lower urinary tract at critical periods for forebrain division and urogenital development. Based on these clinical and molecular findings, we propose the association of PPP1R12A pathogenic variants with a congenital malformations syndrome affecting the embryogenesis of the brain and genitourinary systems and including disorders of sex development.

Disruption of RFX family transcription factors causes autism, attention-deficit/hyperactivity disorder, intellectual disability, and dysregulated behavior.

PURPOSE: We describe a novel neurobehavioral phenotype of autism spectrum disorder (ASD), intellectual disability, and/or attention-deficit/hyperactivity disorder (ADHD) associated with de novo or inherited deleterious variants in members of the RFX family of genes. RFX genes are evolutionarily conserved transcription factors that act as master regulators of central nervous system development and ciliogenesis. METHODS: We assembled a cohort of 38 individuals (from 33 unrelated families) with de novo variants in RFX3, RFX4, and RFX7. We describe their common clinical phenotypes and present bioinformatic analyses of expression patterns and downstream targets of these genes as they relate to other neurodevelopmental risk genes. RESULTS: These individuals share neurobehavioral features including ASD, intellectual disability, and/or ADHD; other frequent features include hypersensitivity to sensory stimuli and sleep problems. RFX3, RFX4, and RFX7 are strongly expressed in developing and adult human brain, and X-box binding motifs as well as RFX ChIP-seq peaks are enriched in the cis-regulatory regions of known ASD risk genes. CONCLUSION: These results establish a likely role of deleterious variation in RFX3, RFX4, and RFX7 in cases of monogenic intellectual disability, ADHD and ASD, and position these genes as potentially critical transcriptional regulators of neurobiological pathways associated with neurodevelopmental disease pathogenesis.

WDR26 Haploinsufficiency Causes a Recognizable Syndrome of Intellectual Disability, Seizures, Abnormal Gait, and Distinctive Facial Features.

We report 15 individuals with de novo pathogenic variants in WDR26. Eleven of the individuals carry loss-of-function mutations, and four harbor missense substitutions. These 15 individuals comprise ten females and five males, and all have intellectual disability with delayed speech, a history of febrile and/or non-febrile seizures, and a wide-based, spastic, and/or stiff-legged gait. These subjects share a set of common facial features that include a prominent maxilla and upper lip that readily reveal the upper gingiva, widely spaced teeth, and a broad nasal tip. Together, these features comprise a recognizable facial phenotype. We compared these features with those of chromosome 1q41q42 microdeletion syndrome, which typically contains WDR26, and noted that clinical features are consistent between the two subsets, suggesting that haploinsufficiency of WDR26 contributes to the pathology of 1q41q42 microdeletion syndrome. Consistent with this, WDR26 loss-of-function single-nucleotide mutations identified in these subjects lead to nonsense-mediated decay with subsequent reduction of RNA expression and protein levels. We derived a structural model of WDR26 and note that missense variants identified in these individuals localize to highly conserved residues of this WD-40-repeat-containing protein. Given that WDR26 mutations have been identified in ∼1 in 2,000 of subjects in our clinical cohorts and that WDR26 might be poorly annotated in exome variant-interpretation pipelines, we would anticipate that this disorder could be more common than currently appreciated.

Expanding the spectrum of CEP55-associated disease to viable phenotypes.

Homozygosity for nonsense variants in CEP55 has been associated with a lethal condition characterized by multinucleated neurons, anhydramnios, renal dysplasia, cerebellar hypoplasia, and hydranencephaly (MARCH syndrome) also known as Meckel-like syndrome. Missense variants in CEP55 have not previously been reported in association with disease. Here we describe seven living individuals from five families with biallelic CEP55 variants. Four unrelated individuals with microcephaly, speech delays, and bilateral toe syndactyly all have a common CEP55 variant c.70G>A p.(Glu24Lys) in trans with nonsense variants. Three siblings are homozygous for a consensus splice site variant near the end of the gene. These affected girls all have severely delayed development, microcephaly, and varying degrees of lissencephaly/pachygyria. Here we compare our seven patients with three previously reported families with a prenatal lethal phenotype (MARCH syndrome/Meckel-like syndrome) due to homozygous CEP55 nonsense variants. Our series suggests that individuals with compound heterozygosity for nonsense and missense variants in CEP55 have a different viable phenotype. We show that homozygosity for a splice variant near the end of the CEP55 gene is also compatible with life.

Participant-reported personal utility of genetic testing for Parkinson's disease and interest in clinical trial participation.

Genetic testing for Parkinson's disease (PD) is infrequently performed due to perceptions of low utility. We investigated the personal utility in PD GENEration and how results lead to enrollment in additional research studies. Participants (n = 972) underwent genetic testing, results disclosure, genetic counseling, and completed a survey examining the perceived personal utility of their results and interest in participating in additional studies. Most participants found their genetic test results useful, including satisfying curiosity (81%), feeling good about helping the medical community (80%), and having information to share with family (77%). There were no significant differences in responses based on result type. Forty-five percent of participants expressed interest in participating in research studies; whereas 16% of participants confirmed enrollment. Our results suggest that participants find personal utility in genetic testing regardless of results. Although participants may be interested in enrolling in additional research, they may need support and resources.

Bi-allelic variants in CELSR3 are implicated in central nervous system and urinary tract anomalies.

CELSR3 codes for a planar cell polarity protein. We describe twelve affected individuals from eleven independent families with bi-allelic variants in CELSR3. Affected individuals presented with an overlapping phenotypic spectrum comprising central nervous system (CNS) anomalies (7/12), combined CNS anomalies and congenital anomalies of the kidneys and urinary tract (CAKUT) (3/12) and CAKUT only (2/12). Computational simulation of the 3D protein structure suggests the position of the identified variants to be implicated in penetrance and phenotype expression. CELSR3 immunolocalization in human embryonic urinary tract and transient suppression and rescue experiments of Celsr3 in fluorescent zebrafish reporter lines further support an embryonic role of CELSR3 in CNS and urinary tract formation.

Imatinib mesylate for plexiform neurofibromas in patients with neurofibromatosis type 1: a phase 2 trial.

BACKGROUND: Plexiform neurofibromas are slow-growing chemoradiotherapy-resistant tumours arising in patients with neurofibromatosis type 1 (NF1). Currently, there are no viable therapeutic options for patients with plexiform neurofibromas that cannot be surgically removed because of their proximity to vital body structures. We undertook an open-label phase 2 trial to test whether treatment with imatinib mesylate can decrease the volume burden of clinically significant plexiform neurofibromas in patients with NF1. METHODS: Eligible patients had to be aged 3-65 years, and to have NF1 and a clinically significant plexiform neurofibroma. Patients were treated with daily oral imatinib mesylate at 220 mg/m(2) twice a day for children and 400 mg twice a day for adults for 6 months. The primary endpoint was a 20% or more reduction in plexiform size by sequential volumetric MRI imaging. Clinical data were analysed on an intention-to-treat basis; a secondary analysis was also done for those patients able to take imatinib mesylate for 6 months. This trial is registered with ClinicalTrials.gov, number NCT01673009. FINDINGS: Six of 36 patients (17%, 95% CI 6-33), enrolled on an intention-to-treat basis, had an objective response to imatinib mesylate, with a 20% or more decrease in tumour volume. Of the 23 patients who received imatinib mesylate for at least 6 months, six (26%, 95% CI 10-48) had a 20% or more decrease in volume of one or more plexiform tumours. The most common adverse events were skin rash (five patients) and oedema with weight gain (six). More serious adverse events included reversible grade 3 neutropenia (two), grade 4 hyperglycaemia (one), and grade 4 increases in aminotransferase concentrations (one). INTERPRETATION: Imatinib mesylate could be used to treat plexiform neurofibromas in patients with NF1. A multi-institutional clinical trial is warranted to confirm these results. FUNDING: Novartis Pharmaceuticals, the Indiana University Simon Cancer Centre, and the Indiana University Herman B Wells Center for Pediatric Research.

Readiness for Parkinson's disease genetic testing and counseling in patients and their relatives in urban settings in the Dominican Republic.

Genetic testing for Parkinson's disease (PD) is increasing globally, and genetic counseling is an important service that provides information and promotes understanding about PD genetics and genetic testing. PD research studies have initiated outreach to underrepresented regions in North America, including regions in Latin America, such as the Dominican Republic (DR); some studies may include return of genetic test results. Thus, understanding what individuals know about PD, genetic testing for PD, and their interest in speaking with a genetic counselor, is crucial when assessing readiness. In this cross-sectional study, a survey was distributed to people with Parkinson's disease (PwP) and their unaffected biological relatives in the DR. Questions assessed genetics knowledge, attitude toward genetic testing, and interest in genetic testing and counseling. Of 45 participants, 69% scored the maximum on the attitude scale, indicating an overall positive attitude toward genetic testing; 95% indicated interest in genetic testing for PD, and 98% were at least somewhat interested in meeting with a genetic counselor. The mean PD genetics knowledge score was similar to previously published data. Through free text responses, participants expressed a desire to know more about PD treatment and management, prevention, cause, and their personal risk for PD. These results provide further evidence of readiness for genetic testing in this country but also underscore some gaps in knowledge that should be addressed with targeted educational efforts, as part of building genetic testing and counseling capacities.

The core FOXG1 syndrome phenotype consists of postnatal microcephaly, severe mental retardation, absent language, dyskinesia, and corpus callosum hypogenesis.

BACKGROUND: Submicroscopic deletions in 14q12 spanning FOXG1 or intragenic mutations have been reported in patients with a developmental disorder described as a congenital variant of Rett syndrome. This study aimed to further characterise and delineate the phenotype of FOXG1 mutation positive patients. METHOD: The study mapped the breakpoints of a 2;14 translocation by fluorescence in situ hybridisation and analysed three chromosome rearrangements in 14q12 by cytogenetic analysis and/or array comparative genomic hybridisation. The FOXG1 gene was sequenced in 210 patients, including 129 patients with unexplained developmental disorders and 81 MECP2 mutation negative individuals. RESULTS: One known mutation, seen in two patients, and nine novel mutations of FOXG1 including two deletions, two chromosome rearrangements disrupting or displacing putative cis-regulatory elements from FOXG1, and seven sequence changes, are reported. Analysis of 11 patients in this study, and a further 15 patients reported in the literature, demonstrates a complex constellation of features including mild postnatal growth deficiency, severe postnatal microcephaly, severe mental retardation with absent language development, deficient social reciprocity resembling autism, combined stereotypies and frank dyskinesias, epilepsy, poor sleep patterns, irritability in infancy, unexplained episodes of crying, recurrent aspiration, and gastro-oesophageal reflux. Brain imaging studies reveal simplified gyral pattern and reduced white matter volume in the frontal lobes, corpus callosum hypogenesis, and variable mild frontal pachgyria. CONCLUSIONS: These findings have significantly expanded the number of FOXG1 mutations and identified two affecting possible cis-regulatory elements. While the phenotype of the patients overlaps both classic and congenital Rett syndrome, extensive clinical evaluation demonstrates a distinctive and clinically recognisable phenotype which the authors suggest designating as the FOXG1 syndrome.

Primary Erythromelalgia Treated With 10% Capsaicin Cream: A Case Report and a 10-Year Follow-Up.

In this case report, we describe the difficulty in finding a suitable treatment for a nine-year-old girl with erythromelalgia. Initially, she could only find pain relief through immersion of her hands and feet in buckets of cool water. Her pain did not respond to outpatient treatments, and she was ultimately admitted to the hospital for pain management. Many different medications and modalities were tried over the course of several weeks in the hospital. Finally, she received the most benefit from 10% compounded capsaicin cream administered under general anesthesia with regional analgesia for post-application pain. Over the course of several years, exacerbations of her pain were treated with additional applications of 10% capsaicin cream, with each application providing relief for an increased duration. Her severe pain flares eventually went into remission after several years. Today, after more than a decade following her initial presentation, she is a successful college student and is taking no medications for her erythromelalgia.

A 9.8 Mb deletion at 7q31.2q31.31 downstream of FOXP2 in an individual with speech and language impairment suggests a possible positional effect.

Haploinsufficiency of FOXP2 causes FOXP2-related speech and language disorder. We report a 9.8 Mb deletion downstream of FOXP2 in a girl with speech and language impairment, developmental delay, and other features. We propose involvement of FOXP2 in pathogenesis of these phenotypes, likely due to positional effects on the gene.

Longitudinal MRI brain findings in the R1349Q pathogenic variant of CACNA1A.

Pathogenic CACNA1A gene variants are associated with a spectrum of disorders including migraine with or without hemiplegia, ataxia, epilepsy, and developmental disability. We present a case of a pathogenic variant (c.4046G>A, p.R1349Q) in the CACNA1A gene associated with a clinical phenotype of global developmental delay, left hemiparesis, epilepsy, and stroke-like episodes. Longitudinal neuroimaging demonstrates hemispheric encephalomalacia with mismatched perfusion and angiographic imaging, in addition to progressive cerebellar atrophy.

Boricua Founder Variant in FRRS1L Causes Epileptic Encephalopathy With Hyperkinetic Movements.

OBJECTIVE: To describe a founder mutation effect and the clinical phenotype of homozygous FRRS1L c.737_739delGAG (p.Gly246del) variant in 15 children of Puerto Rican (Boricua) ancestry presenting with early infantile epileptic encephalopathy (EIEE-37) with prominent movement disorder. BACKGROUND: EIEE-37 is caused by biallelic loss of function variants in the FRRS1L gene, which is critical for AMPA-receptor function, resulting in intractable epilepsy and dyskinesia. METHODS: A retrospective, multicenter chart review of patients sharing the same homozygous FRRS1L (p.Gly246del) pathogenic variant identified by clinical genetic testing. Clinical information was collected regarding neurodevelopmental outcomes, neuroimaging, electrographic features and clinical response to antiseizure medications. RESULTS: Fifteen patients from 12 different families of Puerto Rican ancestry were homozygous for the FRRS1L (p.Gly246del) pathogenic variant, with ages ranging from 1 to 25 years. The onset of seizures was from 6 to 24 months. All had hypotonia, severe global developmental delay, and most had hyperkinetic involuntary movements. Developmental regression during the first year of life was common (86%). Electroencephalogram showed hypsarrhythmia in 66% (10/15), with many older children evolving into Lennox-Gastaut syndrome. Six patients demonstrated progressive volume loss and/or cerebellar atrophy on brain magnetic resonance imaging (MRI). CONCLUSIONS: We describe the largest cohort to date of patients with epileptic encephalopathy. We estimate that 0.76% of unaffected individuals of Puerto Rican ancestry carry this pathogenic variant due to a founder effect. Children homozygous for the FRRS1L (p.Gly246del) Boricua variant exhibit a very homogenous phenotype of early developmental regression and epilepsy, starting with infantile spasms and evolving into Lennox-Gastaut syndrome with hyperkinetic movement disorder.

The impact of Pelizaeus-Merzbacher disease on the family.

The impact of Pelizaeus-Merzbacher disease on families and caregivers of affected children has not been well-studied. Parents, relatives, and caregivers from 18 families with 20 affected children with Pelizaeus-Merzbacher disease were asked to complete the Children's Health Questionnaire-Parent Form 50, an instrument used to assess health-related quality of life in children and family impact of illness. Mean and standard deviation (S.D.) of subscale scores were calculated and compared with previously published norms. Agreement between mothers and fathers was calculated using Cronbach's test. Mean scale scores in this cohort were lower than previously published norms for the following categories: physical function (25.9 vs 96.1, >2 S.D.); family activity (55.6 vs 89.7, >1 S.D.); and parental time impact (66.2 vs 87.8, >1 S.D.). However, family cohesion (73.3 vs 72.3, <1 S.D.), self-esteem (71.1 vs 79.8, <1 S.D.), behavior (78.9 vs 75.6, <1 S.D.), and mental health scale scores (74.2 vs 78.5, <1 S.D.) were similar to previously published norms. Parental agreement was poor, with 5 of 8 parent pairs (63%) differing in their responses (<0.7) Although impact on caregiver time and limitation of physical function and family activities is high, parents and caregivers in the cohort appear to remain cohesive and view their children's psychosocial health as similar to normal children.

Chiari in the family: inheritance of the Chiari I malformation.

This report presents three families with Chiari malformation type I that became symptomatic during childhood: a mother and son; a set of monozygotic twins; and two half-siblings and their two maternal cousins. These children presented with various symptoms, including headache, stiff neck, and swallowing difficulty. A review of the relevant literature is presented, with an emphasis on familial examples and proposed inheritance. Less common presentations of Chiari malformation type I are discussed, as well as the possible pathogenesis of Chiari malformation type I and associated syringomyelia.

A child with Friedreich's ataxia and epilepsy.

Epilepsy in Friedreich's ataxia is rare. We describe a 9-year-old boy with Friedreich's ataxia who had onset of symptoms in the second year of life and developed a generalized epilepsy at age 5 years. On cerebral magnetic resonance imaging, he has a subependymal gray-matter heterotopia. We suggest that his gray-matter heterotopia might be related to his diagnosis of Friedreich's ataxia and that his early onset of symptoms might be related to the length of his guanine-adenine-adenine (GAA) triplet repeat expansion.

Clinical findings in Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease is a rare X-linked disease characterized by defective central nervous system myelination owing to a mutation in the proteolipid protein 1 gene. Few studies report detailed clinical findings in children with genetic confirmation of mutations in the proteolipid protein 1 gene. We reviewed the records of 10 boys with Pelizaeus-Merzbacher disease and one symptomatic carrier girl. Their median age was 2 1/2 years (range 10 months to 20 years). Nine had proteolipid protein 1 gene duplications, one had a point mutation, and one had a single codon deletion. The families of eight patients reported perinatal complications, including maternal hypertension (three patients) and meconium aspiration (three patients). All of the patients were social and interactive, but all had difficulty with expressive speech. All patients presented with nystagmus and had hypotonia that progressed to spasticity, affecting the legs more than the arms; ataxia also contributed to motor impairment. Additional problems reported regarded feeding (eight patients) and sleep (three patients). Further work is needed to clarify the variations in disease course and the relationship of genotype to phenotype.

Is it ADEM, POLG, or both?

OBJECTIVE: To describe a child with apparent brain biopsy-confirmed acute disseminated encephalomyelitis (ADEM) but genetic confirmation of compound heterozygosity for DNA mutations of the polymerase gamma (POLG) gene. DESIGN: Case report. SETTING: Tertiary referral center. PATIENT: A 4-year-old boy presented with ataxia and encephalopathy. RESULTS: Magnetic resonance imaging demonstrated multiple focal areas of T2 prolongation. The patient's family refused steroid treatment. His symptoms improved then progressed. Magnetic resonance imaging findings also progressed. A cerebrospinal fluid specimen revealed myelin basic protein and oligoclonal bands. A brain biopsy specimen demonstrated demyelination, suggesting progression of ADEM. However, polymerase chain reaction amplification and sequencing revealed 2 heterozygous mutations of the POLG gene, suggesting mitochondrial disease. The patient died 9 months after his initial presentation. CONCLUSIONS: This case raises interesting questions about whether ADEM triggered severe neurologic degeneration in a patient with mitochondrial disease, whether mitochondrial disease predisposed to a pathologic immune response, or whether mitochondrial disease can mimic an autoimmune disease. Mitochondrial disease-causing mutations may help explain the poor outcome in some cases of apparent autoimmune central nervous system disease.

Rituximab for the treatment of thymoma-associated and de novo myasthenia gravis: 3 cases and review.

OBJECTIVES: Myasthenia gravis (MG) is an immune-mediated disorder associated with autoantibodies against postsynaptic nicotinic acetylcholine receptors at neuromuscular junctions. Rituximab, a monoclonal antibody specific for CD20, is used primarily to treat B-cell non-Hodgkin lymphoma. Although it has been used for treatment of a number of autoimmune diseases, there is limited experience in MG. METHODS: Three patients with refractory MG (2 with concurrent thymoma) were given rituximab. RESULTS: Symptoms stabilized and reductions in immunosuppressive medications were tolerated for extended periods, without adverse effects or infectious complications. CONCLUSIONS: These observations support the concept that rituximab may be helpful for the treatment of MG. Remissions in patients with or without thymoma are achievable with rituximab given in combination with commonly used modalities. Furthermore, rituximab is not necessarily contraindicated for the treatment of MG in patients being treated for thymoma. Controlled studies are called for to define its role in the treatment of refractory MG.