Publications by authors named "Ralitza H Gavrilova"

45 Publications

Brain volumetric deficits in MAPT mutation carriers: a multisite study.

Ann Clin Transl Neurol 2021 01 28;8(1):95-110. Epub 2020 Nov 28.

Memory and Aging Center, Department of Neurology, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, California, USA.

Objective: MAPT mutations typically cause behavioral variant frontotemporal dementia with or without parkinsonism. Previous studies have shown that symptomatic MAPT mutation carriers have frontotemporal atrophy, yet studies have shown mixed results as to whether presymptomatic carriers have low gray matter volumes. To elucidate whether presymptomatic carriers have lower structural brain volumes within regions atrophied during the symptomatic phase, we studied a large cohort of MAPT mutation carriers using a voxelwise approach.

Methods: We studied 22 symptomatic carriers (age 54.7 ± 9.1, 13 female) and 43 presymptomatic carriers (age 39.2 ± 10.4, 21 female). Symptomatic carriers' clinical syndromes included: behavioral variant frontotemporal dementia (18), an amnestic dementia syndrome (2), Parkinson's disease (1), and mild cognitive impairment (1). We performed voxel-based morphometry on T1 images and assessed brain volumetrics by clinical subgroup, age, and mutation subtype.

Results: Symptomatic carriers showed gray matter atrophy in bilateral frontotemporal cortex, insula, and striatum, and white matter atrophy in bilateral corpus callosum and uncinate fasciculus. Approximately 20% of presymptomatic carriers had low gray matter volumes in bilateral hippocampus, amygdala, and lateral temporal cortex. Within these regions, low gray matter volumes emerged in a subset of presymptomatic carriers as early as their thirties. Low white matter volumes arose infrequently among presymptomatic carriers.

Interpretation: A subset of presymptomatic MAPT mutation carriers showed low volumes in mesial temporal lobe, the region ubiquitously atrophied in all symptomatic carriers. With each decade of age, an increasing percentage of presymptomatic carriers showed low mesial temporal volume, suggestive of early neurodegeneration.
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http://dx.doi.org/10.1002/acn3.51249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818091PMC
January 2021

Defining the genotypic and phenotypic spectrum of X-linked MSL3-related disorder.

Genet Med 2021 Feb 11;23(2):384-395. Epub 2020 Nov 11.

Institute of Human Genetics, Technical University Munich, Munich, Germany.

Purpose: We sought to delineate the genotypic and phenotypic spectrum of female and male individuals with X-linked, MSL3-related disorder (Basilicata-Akhtar syndrome).

Methods: Twenty-five individuals (15 males, 10 females) with causative variants in MSL3 were ascertained through exome or genome sequencing at ten different sequencing centers.

Results: We identified multiple variant types in MSL3 (ten nonsense, six frameshift, four splice site, three missense, one in-frame-deletion, one multi-exon deletion), most proven to be de novo, and clustering in the terminal eight exons suggesting that truncating variants in the first five exons might be compensated by an alternative MSL3 transcript. Three-dimensional modeling of missense and splice variants indicated that these have a deleterious effect. The main clinical findings comprised developmental delay and intellectual disability ranging from mild to severe. Autism spectrum disorder, muscle tone abnormalities, and macrocephaly were common as well as hearing impairment and gastrointestinal problems. Hypoplasia of the cerebellar vermis emerged as a consistent magnetic resonance image (MRI) finding. Females and males were equally affected. Using facial analysis technology, a recognizable facial gestalt was determined.

Conclusion: Our aggregated data illustrate the genotypic and phenotypic spectrum of X-linked, MSL3-related disorder (Basilicata-Akhtar syndrome). Our cohort improves the understanding of disease related morbidity and allows us to propose detailed surveillance guidelines for affected individuals.
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http://dx.doi.org/10.1038/s41436-020-00993-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7862064PMC
February 2021

Impact of integrated translational research on clinical exome sequencing.

Genet Med 2020 Nov 4. Epub 2020 Nov 4.

Center for Individualized Medicine, College of Medicine, Mayo Clinic, Rochester, MN, USA.

Purpose: Exome sequencing often identifies pathogenic genetic variants in patients with undiagnosed diseases. Nevertheless, frequent findings of variants of uncertain significance necessitate additional efforts to establish causality before reaching a conclusive diagnosis. To provide comprehensive genomic testing to patients with undiagnosed disease, we established an Individualized Medicine Clinic, which offered clinical exome testing and included a Translational Omics Program (TOP) that provided variant curation, research activities, or research exome sequencing.

Methods: From 2012 to 2018, 1101 unselected patients with undiagnosed diseases received exome testing. Outcomes were reviewed to assess impact of the TOP and patient characteristics on diagnostic rates through descriptive and multivariate analyses.

Results: The overall diagnostic yield was 24.9% (274 of 1101 patients), with 174 (15.8% of 1101) diagnosed on the basis of clinical exome sequencing alone. Four hundred twenty-three patients with nondiagnostic or without access to clinical exome sequencing were evaluated by the TOP, with 100 (9% of 1101) patients receiving a diagnosis, accounting for 36.5% of the diagnostic yield. The identification of a genetic diagnosis was influenced by the age at time of testing and the disease phenotype of the patient.

Conclusion: Integration of translational research activities into clinical practice of a tertiary medical center can significantly increase the diagnostic yield of patients with undiagnosed disease.
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http://dx.doi.org/10.1038/s41436-020-01005-9DOI Listing
November 2020

Expansion of -Related Phenotypes and Discovery of a Novel PURA Variant: A Case Report.

Child Neurol Open 2020 Jan-Dec;7:2329048X20955003. Epub 2020 Oct 14.

Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA.

Variants in have recently been associated with an autosomal dominant form of -related neurodevelopmental disorders. Using whole exome sequencing, patients with neurological phenotypes including hypotonia, developmental delay, learning disabilities, and seizures were identified to have de novo variants in . We describe a proband with features similar to the previously described cases with variants, but including additional features, such as short stature, delayed bone age, and delayed puberty. Exome sequencing revealed a novel pathogenic nonsense variant, c.190A>T (p.Lys64*; NM_005859), in that was not inherited from the proband's mother. In the recent literature, a significant number of patients with variants in have been described, but to our knowledge, none of these patients have the delayed bone age and growth plateau observed in the proband. It is therefore possible that the above PURA variant may be responsible for the novel features and thus expands the PURA-related phenotype spectrum.
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http://dx.doi.org/10.1177/2329048X20955003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573717PMC
October 2020

Iron Deficiency and Its Role in Sleep Disruption in Patients With Angelman Syndrome.

J Child Neurol 2020 Dec 27;35(14):963-969. Epub 2020 Jul 27.

Department of Neurology, 4352Mayo Clinic, Rochester, MN, USA.

Objective: To determine if Angelman syndrome patients with sleep complaints have an increased risk of iron deficiency, and if iron therapy improves their sleep difficulties.

Background: About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial. Because iron deficiency can contribute toward restlessness in sleep, we investigated whether it might be a contributing factor in this special population.

Methods: This retrospective study involved medical record review of Angelman syndrome patients <18 years old who had attended our multidisciplinary Angelman syndrome clinic and had sleep complaints. Serum ferritin levels were compared to age- and sex-matched controls. Sleep history and nocturnal polysomnogram findings of the Angelman syndrome patients were also characterized.

Results: Nineteen Angelman syndrome patients (9 female, mean age 6.2±4.4 years) were identified. All 19 reported sleep difficulties. The mean serum ferritin level was 19.9±8.5 μg/L, while that in controls was 27.8±17.8 μg/L ( value .13). The odds ratio of iron deficiency in Angelman syndrome compared to controls was 4.17 (95% confidence interval 1.23-14.10), using normal serum ferritin level of 24 μg/L based on literature. Fifteen Angelman syndrome patients underwent nocturnal polysomnogram with 9/15 showing an elevated periodic limb movement index (overall mean 9.8±10.4). Seventeen of 19 received iron therapy. Twelve had follow-up after iron therapy, with parents reporting improved sleep quality. Eight had serum ferritin levels rechecked after iron therapy, showing a mean increase of 24±5.1 μg/L.

Conclusions: Sleep difficulties in Angelman syndrome, though multifactorial, may in part be related to iron deficiency. Treatment with iron improved sleep to a modest degree in this population.
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http://dx.doi.org/10.1177/0883073820941755DOI Listing
December 2020

Safety and efficacy of (+)-epicatechin in subjects with Friedreich's ataxia: A phase II, open-label, prospective study.

J Inherit Metab Dis 2020 Jul 16. Epub 2020 Jul 16.

Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.

Background: (+)-Epicatechin (EPI) induces mitochondrial biogenesis and antioxidant metabolism in muscle fibers and neurons. We aimed to evaluate safety and efficacy of (+)-EPI in pediatric subjects with Friedreich's ataxia (FRDA).

Methods: This was a phase II, open-label, baseline-controlled single-center trial including 10 participants ages 10 to 22 with confirmed FA diagnosis. (+)-EPI was administered orally at 75 mg/d for 24 weeks, with escalation to 150 mg/d at 12 weeks for subjects not showing improvement of neuromuscular, neurological or cardiac endpoints. Neurological endpoints were change from baseline in Friedreich's Ataxia Rating Scale (FARS) and 8-m timed walk. Cardiac endpoints were changes from baseline in left ventricular (LV) structure and function by cardiac magnetic resonance imaging (MRI) and echocardiogram, changes in cardiac electrophysiology, and changes in biomarkers for heart failure and hypertrophy.

Results: Mean FARS/modified (m)FARS scores showed nonstatistically significant improvement by both group and individual analysis. FARS/mFARS scores improved in 5/9 subjects (56%), 8-m walk in 3/9 (33%), 9-peg hole test in 6/10 (60%). LV mass index by cardiac MRI was significantly reduced at 12 weeks (P = .045), and was improved in 7/10 (70%) subjects at 24 weeks. Mean LV ejection fraction was increased at 24 weeks (P = .008) compared to baseline. Mean maximal septal thickness by echocardiography was increased at 24 weeks (P = .031). There were no serious adverse events.

Conclusion: (+)-EPI was well tolerated over 24 weeks at up to 150 mg/d. Improvement was observed in cardiac structure and function in subset of subjects with FRDA without statistically significant improvement in primary neurological outcomes.

Synopsis: A (+)-epicatechin showed improvement of cardiac function, nonsignificant reduction of FARS/mFARS scores, and sustained significant upregulation of muscle-regeneration biomarker follistatin.
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http://dx.doi.org/10.1002/jimd.12285DOI Listing
July 2020

De novo variants of NR4A2 are associated with neurodevelopmental disorder and epilepsy.

Genet Med 2020 Aug 5;22(8):1413-1417. Epub 2020 May 5.

Department of Genetics, University Medical Centre Utrecht, Utrecht, The Netherlands.

Purpose: This study characterizes the clinical and genetic features of nine unrelated patients with de novo variants in the NR4A2 gene.

Methods: Variants were identified and de novo origins were confirmed through trio exome sequencing in all but one patient. Targeted RNA sequencing was performed for one variant to confirm its splicing effect. Independent discoveries were shared through GeneMatcher.

Results: Missense and loss-of-function variants in NR4A2 were identified in patients from eight unrelated families. One patient carried a larger deletion including adjacent genes. The cases presented with developmental delay, hypotonia (six cases), and epilepsy (six cases). De novo status was confirmed for eight patients. One variant was demonstrated to affect splicing and result in expression of abnormal transcripts likely subject to nonsense-mediated decay.

Conclusion: Our study underscores the importance of NR4A2 as a disease gene for neurodevelopmental disorders and epilepsy. The identified variants are likely causative of the seizures and additional developmental phenotypes in these patients.
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http://dx.doi.org/10.1038/s41436-020-0815-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7394879PMC
August 2020

Mitochondrial diseases in North America: An analysis of the NAMDC Registry.

Neurol Genet 2020 Apr 2;6(2):e402. Epub 2020 Mar 2.

Department of Neurology (E.B., V.E., S.D., K.E., X.Q.R., M.H.), Columbia University Medical Center, New York; Department of Biostatistics (Y.L., V.C., J.K., J. Grier, R.B., J.L.P.T.), Mailman School of Public Health, Columbia University, New York; Radboudumc (R.S.), Nijmegen, The Netherlands; Department of Pediatrics (B.H.C.), Northeast Ohio Medical University and Akron Children's Hospital; Genetics Unit (A.K.), Massachusetts General Hospital, Boston; Department of Pediatrics (G.D.V.), State University of New York at Buffalo; Departments of Neurosciences and Pediatrics (R.H.), University of California at San Diego; Department of Pediatrics (J.L.K.V.H., A.L.), University of Colorado School of Medicine, Aurora; Department of Molecular and Human Genetics (F.S.), Baylor College of Medicine, Houston, TX; Texas Children's Hospital (F.S.), Houston; Joint BCM-CUHK Center of Medical Genetics (F.S.), Prince of Wales Hospital, ShaTin, New Territories, Hong Kong; Department of Neurology (S.P.), Cleveland Clinic, OH; Departments of Genetics and Genome Sciences and Pediatrics (J.K.B., S.D.D.), and Center for Human Genetics, University Hospitals Cleveland Medical Center, Case Western Reserve University, OH; Departments of Neurology and Clinical Genomics (R.H.G.), Mayo Clinic, Rochester, MN; Department of Neurology (R.P.S.), University of Washington, Seattle Children's Hospital; Department of Pediatrics (G.M.E.), Stanford University, Palo Alto, CA; Department of Medicine (P.W.S.), University of Florida at Gainesville; Genetics and Genomic Sciences at the Icahn School of Medicine at Mount Sinai (J. Ganesh), New York; Mitochondrial Medicine Frontier Program (Z.Z.-C., M.J.F., A.C.G.), Division of Human Genetics, The Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine; University of Pennsylvania Perelman School of Medicine (Z.Z.-C.), Philadelphia; Department of Neurology (M.T.), McMasters University, Toronto, Ontario, Canada; Department of Neurology (A.G.), Children's National Health Network, Washington, DC; Office of Dietary Supplements (K.C.), National Institutes of Health, Bethesda, MD; and Eunice Kennedy Shriver National Institute of Child Health and Human Development (D.K.), National Institutes of Health, Bethesda, MD.

Objective: To describe clinical, biochemical, and genetic features of participants with mitochondrial diseases (MtDs) enrolled in the North American Mitochondrial Disease Consortium (NAMDC) Registry.

Methods: This cross-sectional, multicenter, retrospective database analysis evaluates the phenotypic and molecular characteristics of participants enrolled in the NAMDC Registry from September 2011 to December 2018. The NAMDC is a network of 17 centers with expertise in MtDs and includes both adult and pediatric specialists.

Results: One thousand four hundred ten of 1,553 participants had sufficient clinical data for analysis. For this study, we included only participants with molecular genetic diagnoses (n = 666). Age at onset ranged from infancy to adulthood. The most common diagnosis was multisystemic disorder (113 participants), and only a minority of participants were diagnosed with a classical mitochondrial syndrome. The most frequent classical syndromes were Leigh syndrome (97 individuals) and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (71 individuals). Pathogenic variants in the mitochondrial DNA were more frequently observed (414 participants) than pathogenic nuclear gene variants (252 participants). Pathogenic variants in 65 nuclear genes were identified, with and being the most commonly affected. Pathogenic variants in 38 genes were reported only in single participants.

Conclusions: The NAMDC Registry data confirm the high variability of clinical, biochemical, and genetic features of participants with MtDs. This study serves as an important resource for future enhancement of MtD research and clinical care by providing the first comprehensive description of participant with MtD in North America.
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http://dx.doi.org/10.1212/NXG.0000000000000402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164977PMC
April 2020

Loss-of-function mutations in UDP-Glucose 6-Dehydrogenase cause recessive developmental epileptic encephalopathy.

Nat Commun 2020 01 30;11(1):595. Epub 2020 Jan 30.

Institute of Medical Biology, A*STAR, Biopolis, Singapore, 138648, Singapore.

Developmental epileptic encephalopathies are devastating disorders characterized by intractable epileptic seizures and developmental delay. Here, we report an allelic series of germline recessive mutations in UGDH in 36 cases from 25 families presenting with epileptic encephalopathy with developmental delay and hypotonia. UGDH encodes an oxidoreductase that converts UDP-glucose to UDP-glucuronic acid, a key component of specific proteoglycans and glycolipids. Consistent with being loss-of-function alleles, we show using patients' primary fibroblasts and biochemical assays, that these mutations either impair UGDH stability, oligomerization, or enzymatic activity. In vitro, patient-derived cerebral organoids are smaller with a reduced number of proliferating neuronal progenitors while mutant ugdh zebrafish do not phenocopy the human disease. Our study defines UGDH as a key player for the production of extracellular matrix components that are essential for human brain development. Based on the incidence of variants observed, UGDH mutations are likely to be a frequent cause of recessive epileptic encephalopathy.
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http://dx.doi.org/10.1038/s41467-020-14360-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992768PMC
January 2020

Genetic variants in DGAT1 cause diverse clinical presentations of malnutrition through a specific molecular mechanism.

Eur J Med Genet 2020 Apr 25;63(4):103817. Epub 2019 Nov 25.

Bioinformatics Research and Development Laboratory, Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Clinical and Translational Sciences Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA. Electronic address:

Background: DGAT1, a gene encoding a protein involved in lipid metabolism, has been recently implicated in causing a rare nutritional and digestive disease presenting as Congenital Diarrheal Disorder (CDD). Genetic causes of malnutrition can be classified as metabolic disorders, caused by loss of a specific enzyme's function. However, disease driven by genetic variants in lipid metabolism genes is not well understood, and additional information is needed to better understand these effects.

Methods: We gathered a multi-institutional cohort of undiagnosed patients with a constellation of phenotypes presenting as malnutrition and metal ion dysregulation. Clinical Whole Exome Sequencing (WES) was performed on four patients and their unaffected parents. We prioritized genetic variants based on multiple criteria including population allele frequency and presumed inheritance pattern, and identified a candidate gene. Computational modeling was used to investigate if the altered amino acids are likely to result in a dysfunctional enzyme.

Results: We identified a multi-institutional cohort of patients presenting with malnutrition-like symptoms and likely pathogenic genomic variants within DGAT1. Multiple approaches were used to profile the effect these variants have on protein structure and function. Laboratory and nutritional intervention studies showed rapid and robust patient responses.

Conclusions: This report adds on to the database for existing mutations known within DGAT1, a gene recently implicated with CDD, and also expands its clinical spectrum. Identification of these DGAT1 mutations by WES has allowed for changes in the patients' nutritional rehabilitation, reversed growth failure and enabled them to be weaned off of total parenteral nutrition (TPN).
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http://dx.doi.org/10.1016/j.ejmg.2019.103817DOI Listing
April 2020

Tracking white matter degeneration in asymptomatic and symptomatic MAPT mutation carriers.

Neurobiol Aging 2019 11 15;83:54-62. Epub 2019 Aug 15.

Department of Radiology, Mayo Clinic, Rochester, MN, USA. Electronic address:

Our aim was to investigate the patterns and trajectories of white matter (WM) diffusion abnormalities in microtubule-associated protein tau (MAPT) mutations carriers. We studied 22 MAPT mutation carriers (12 asymptomatic, 10 symptomatic) and 20 noncarriers from 8 families, who underwent diffusion tensor imaging (DTI) and a subset (10 asymptomatic, 6 symptomatic MAPT mutation carriers, and 10 noncarriers) were followed annually (median = 4 years). Cross-sectional and longitudinal changes in mean diffusivity (MD) and fractional anisotropy were analyzed. Asymptomatic MAPT mutation carriers had higher MD in entorhinal WM, which propagated to the limbic tracts and frontotemporal projections in the symptomatic stage compared with noncarriers. Reduced fractional anisotropy and increased MD in the entorhinal WM were associated with the proximity to estimated and actual age of symptom onset. The annualized change of entorhinal MD on serial DTI was accelerated in MAPT mutation carriers compared with noncarriers. Entorhinal WM diffusion abnormalities precede the symptom onset and track with disease progression in MAPT mutation carriers. Our cross-sectional and longitudinal data showed a potential clinical utility for DTI to track neurodegenerative disease progression for MAPT mutation carriers in clinical trials.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.08.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6858933PMC
November 2019

Three rare disease diagnoses in one patient through exome sequencing.

Cold Spring Harb Mol Case Stud 2019 12 13;5(6). Epub 2019 Dec 13.

Center for Individualized Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.

Diagnostic exome sequencing yields a single genetic diagnosis in ∼30% of cases, and according to recent studies the prevalence of identifying two genetic conditions in a single individual range between 4.6% and 7%. We present a patient diagnosed with three different rare conditions, each explained by a pathogenic variant in a different gene. A 17-yr-old female was evaluated for a history of motor and speech delay, scoliosis, distinctive craniofacial features, and dry skin in the Department of Clinical Genomics at Mayo Clinic. Her distinctive features included prominent forehead, epicanthus, depressed nasal bridge, narrow mouth, prognathism, malar flattening, and oligodontia. Family history was notable for dry skin in her mother and missing teeth in the paternal grandmother. Previous diagnostic testing was unrevealing including biochemical testing, echocardiogram, abdominal ultrasound, and electroencephalogram. Previous genetic testing included a microarray-based comparative genomic hybridization that was reported normal. Three pathogenic loss-of-function heterozygous variants were identified by exome trio sequencing, each linked to different genetic conditions: (Witteveen-Kolk syndrome), (dermatitis), and (ectodermal dysplasia). Together, these three genetic alterations could explain the patient's overall phenotype. This patient demonstrates the importance of performing a thorough curation of exome data when presented with a complex phenotype. Although phenotypic variability can explain some of these situations, the hypothesis of multiple diseases coexisting in a single patient should never be disregarded completely.
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http://dx.doi.org/10.1101/mcs.a004390DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6913146PMC
December 2019

AMPA receptor GluA2 subunit defects are a cause of neurodevelopmental disorders.

Nat Commun 2019 07 12;10(1):3094. Epub 2019 Jul 12.

Department of Neuromuscular Disorders, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK.

AMPA receptors (AMPARs) are tetrameric ligand-gated channels made up of combinations of GluA1-4 subunits encoded by GRIA1-4 genes. GluA2 has an especially important role because, following post-transcriptional editing at the Q607 site, it renders heteromultimeric AMPARs Ca-impermeable, with a linear relationship between current and trans-membrane voltage. Here, we report heterozygous de novo GRIA2 mutations in 28 unrelated patients with intellectual disability (ID) and neurodevelopmental abnormalities including autism spectrum disorder (ASD), Rett syndrome-like features, and seizures or developmental epileptic encephalopathy (DEE). In functional expression studies, mutations lead to a decrease in agonist-evoked current mediated by mutant subunits compared to wild-type channels. When GluA2 subunits are co-expressed with GluA1, most GRIA2 mutations cause a decreased current amplitude and some also affect voltage rectification. Our results show that de-novo variants in GRIA2 can cause neurodevelopmental disorders, complementing evidence that other genetic causes of ID, ASD and DEE also disrupt glutamatergic synaptic transmission.
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http://dx.doi.org/10.1038/s41467-019-10910-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6626132PMC
July 2019

itochondrial erebellar taxia, enal failure, europathy, and ncephalopathy (MCARNE).

Neurol Genet 2019 Apr 6;5(2):e314. Epub 2019 Mar 6.

Department of Neurology (P.S.N., M.V.P., C.J.K.), Department of Laboratory Genetics and Genomics (J.L.N., L.H., E.W.H.), Department of Anatomic Pathology (J.L.N., M.E.F.), and Department of Clinical Genomics (R.H.G.), Mayo Clinic and Mayo Foundation, Rochester, MN.

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http://dx.doi.org/10.1212/NXG.0000000000000314DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6454306PMC
April 2019

Developmental delay, coarse facial features, and epilepsy in a patient with gene variants.

Clin Case Rep 2019 Apr 19;7(4):632-637. Epub 2019 Feb 19.

Department of Clinical Genomics Mayo Clinic Rochester Minnesota.

We report a patient with developmental delay, autism, epilepsy, macrocephaly, facial dysmorphism, gastrointestinal, and behavioral issues due to compound heterozygous likely pathogenic variants. This case report expands the gene mutation database and the clinical spectrum of patients with deficiencies in the heparan sulfate pathway.
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http://dx.doi.org/10.1002/ccr3.2010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6452521PMC
April 2019

Clinical spectrum of -related epileptic disorders.

Neurology 2019 03 8;92(11):e1238-e1249. Epub 2019 Feb 8.

From the University of Tübingen (S. Wolking, J.M., Y.G.W., H.L., J.S.), Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, Tübingen, Germany; Luxembourg Centre for Systems Biomedicine (P.M.), University of Luxembourg, Esch-sur-Alzette; Pediatric Neurology and Neurogenetics Unit and Laboratories (D.M., R.G., C.M.), Children's Hospital Anna Meyer, University of Florence, Italy; Danish Epilepsy Centre (R.S.M.), Dianalund; Institute for Regional Health Services (R.S.M.), University of Southern Denmark, Odense; Department of Clinical and Experimental Epilepsy (S.B.), UCL Institute of Neurology and Epilepsy Society, UK, London; Division of Neurology (K.L.H., I.H.), Children's Hospital of Philadelphia, PA; Department of Pediatric Neurology (C.D.A.), Centre de Compétences Maladies Rares, CHU Besançon; Service de Génétique (N.C.), Hospices Civils des Lyon, Bron; GENDEV Team (N.C.), Neurosciences Research Center of Lyon, Bron, France; Neuropediatric Clinic and Clinic for Neurorehabilitation (K.S.), Epilepsy Center for Children and Adolescents, Schoen Klinik Vogtareuth, Germany; Beaumont Hospital (P.W.-W.), Dublin, Ireland; Department of Pediatrics, Division of Medical Genetics, Institute of Human Genetics (B.A.M.), Departments of Neurology and Pediatrics (A.N.), and Departments of Neurology and Pediatrics, and Institute of Human Genetics (M.R.C.), University of California, San Francisco; Department of Neurology (W.V.P.), University Hospitals Leuven, Belgium; Department of Pediatrics (L.L.S.), Hvidovre Hospital, Denmark; King's College Hospital (S.O., E.H., S.G., D.K.P.), London; Evelina London Children's Hospital (S.O., E.H., S.G.), London, UK; Section of Genetics (K.B., M.S.S.), Department of Pediatrics, University of Colorado and Children's Hospital Colorado, Aurora; Clinique Bernoise Montana (T.D.), Crans-Montana, Switzerland; Department of Neuropediatrics (H.M.), University Medical Center Schleswig-Holstein, Christian-Albrechts University, Kiel, Germany; National Institute for Health Research Oxford Biomedical Research Centre, Wellcome Centre for Human Genetics (A.T.P., S.J.L.K., J.C.T.) and Department of Oncology (D.V.V.), University of Oxford, UK; Epilepsy Center (M.P.C.), Health Sciences Department, San Paolo Hospital, University of Milan; Child Neuropsychiatry (F.D.), Department of Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, Italy; Departments of Neurology and Clinical Genomics (R.H.G.) and Health Sciences Research and Clinical Genomics (E.W.K., C.K.), Mayo Clinic, Rochester, MN; Ambry Genetics (Z.P.), Aliso Viejo, CA; Department of Clinical Neuroscience (S.T.), King's College London; New Medicines (M.A., D.M.), UCB Pharma, Slough, UK; Neuropediatric Clinic and Clinic for Neurorehabilitation (G.J.K.), Epilepsy Center for Children and Adolescents, Schoen Klinik Vogtareuth, Germany; Research Institute for Rehabilitation, Transition and Palliation (G.J.K.), PMU Salzburg, Austria; Department of Neurology (D.H.L.), University of California, San Francisco; Neurogenetics Group (S. Weckhuysen), Center for Molecular Neurology, VIB, Antwerp; Laboratory of Neurogenetics (S. Weckhuysen), Institute Born-Bunge, University of Antwerp; Department of Neurology (S. Weckhuysen), Antwerp University Hospital, Antwerp, Belgium; Department of Basic & Clinical Neuroscience, Institute of Psychiatry, Psychology & Neuroscience (D.K.P.), MRC Centre for Neurodevelopmental Disorders (D.K.P.), King's College London, UK; Evelina London Children's Hospital (D.K.P.), London, UK; Department of Neuropediatrics (I.H.), University Medical Center Schleswig-Holstein, Christian-Albrechts University, Kiel, Germany; Institute of Neuroscience (R.H.T.), Henry Wellcome Building, Newcastle University; Neurology Research Group (M.I.R.), Institute of Life Science, Swansea University Medical School, Swansea, UK; Service de Génétique (G.L.), Hospices Civils des Lyon, Bron; GENDEV Team (G.L.), Neurosciences Research Center of Lyon, Bron, France; NIHR University College London Hospitals Biomedical Research Centre (S.M.S.), UCL Institute of Neurology, London, UK; Cologne Center for Genomics (D.L.), University of Cologne, Germany; Stanley Center for Psychiatric Research (D.L.) and Program in Medical and Population Genetics (D.L.), Broad Institute of MIT and Harvard, Cambridge; Psychiatric and Neurodevelopmental Genetics Unit (D.L.), Massachusetts General Hospital and Harvard Medical School, Boston.

Objective: The aim of this study was to expand the spectrum of epilepsy syndromes related to , encoding the presynaptic protein syntaxin-1B, and establish genotype-phenotype correlations by identifying further disease-related variants.

Methods: We used next-generation sequencing in the framework of research projects and diagnostic testing. Clinical data and EEGs were reviewed, including already published cases. To estimate the pathogenicity of the variants, we used established and newly developed in silico prediction tools.

Results: We describe 17 new variants in , which are distributed across the whole gene. We discerned 4 different phenotypic groups across the newly identified and previously published patients (49 patients in 23 families): (1) 6 sporadic patients or families (31 affected individuals) with febrile and afebrile seizures with a benign course, generally good drug response, normal development, and without permanent neurologic deficits; (2) 2 patients with genetic generalized epilepsy without febrile seizures and cognitive deficits; (3) 13 patients or families with intractable seizures, developmental regression after seizure onset and additional neuropsychiatric symptoms; (4) 2 patients with focal epilepsy. More often, we found loss-of-function mutations in benign syndromes, whereas missense variants in the SNARE motif of syntaxin-1B were associated with more severe phenotypes.

Conclusion: These data expand the genetic and phenotypic spectrum of -related epilepsies to a diverse range of epilepsies that span the International League Against Epilepsy classification. Variants in are protean and contribute to many different epilepsy phenotypes, similar to , the most important gene associated with fever-associated epilepsies.
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http://dx.doi.org/10.1212/WNL.0000000000007089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511102PMC
March 2019

GFAP canonical transcript may not be suitable for the diagnosis of adult-onset Alexander disease.

Acta Neuropathol Commun 2018 10 24;6(1):112. Epub 2018 Oct 24.

Center for Individualized Medicine, Mayo Clinic, Harwick 3, 200 First Street SW, Rochester, MN, 55905, USA.

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http://dx.doi.org/10.1186/s40478-018-0616-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6201530PMC
October 2018

Developmental delay and failure to thrive associated with a loss-of-function variant in WHSC1 (NSD2).

Am J Med Genet A 2018 12 22;176(12):2798-2802. Epub 2018 Oct 22.

Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota.

Wolf-Hirschhorn syndrome (WHS) is a microdeletion syndrome characterized by distinctive facial features consisting of "Greek warrior helmet" appearance, prenatal and postnatal growth deficiency, developmental disability, and seizures. This disorder is caused by heterozygous deletions on chromosome 4p16.3 often identified by cytogenetic techniques. Many groups have attempted to identify the critical region within this deletion to establish which genes are responsible for WHS. Herein, clinical whole exome sequencing (WES) was performed on a child with developmental delays, mild facial dysmorphisms, short stature, failure to thrive, and microcephaly, and revealed a de novo frameshift variant, c.1676_1679del (p.Arg559Tfs*38), in WHSC1 (NSD2). While WHSC1 falls within the WHS critical region, individuals with only disruption of this gene have only recently been described in the literature. Loss-of-function de novo variations in WHSC1 were identified in large developmental delay, autism, diagnostic, and congenital cardiac cohorts, as well as recent case reports, suggesting that de novo loss-of-function WHSC1 variants may be related to disease. These findings, along with our patient suggest that loss-of-function variation in WHSC1 may lead to a mild form of Wolf-Hirschhorn syndrome, and also may suggest that the developmental delays, facial dysmorphisms, and short stature seen in WHS may be due to disruption of WHSC1 gene.
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http://dx.doi.org/10.1002/ajmg.a.40498DOI Listing
December 2018

CKD Due to a Novel Mitochondrial DNA Mutation: A Case Report.

Am J Kidney Dis 2019 02 8;73(2):273-277. Epub 2018 Oct 8.

Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, MN. Electronic address:

In human kidney disease, mitochondrial ultrastructural damage has long been recognized. Although the extent to which such mitochondrial changes contribute to human kidney disease is uncertain, experimental studies clearly demonstrate that mitochondrial damage can instigate pathogenetic processes that drive ongoing kidney disease. Clinical credence for this experimentally based hypothesis is provided by the development of kidney disease in patients with primary mitochondrial disorders. In this regard, substantial interest surrounds the occurrence of kidney disease in primary mitochondrial cytopathies, a heterogeneous group of conditions in which mutations in mitochondrial DNA (mtDNA) or nuclear DNA impair the functionality of components of the mitochondrial respiratory chain. We describe a novel mtDNA mutation in a patient who developed chronic kidney disease. The patient exhibited mitochondrial abnormalities in both muscle and kidney, chronic tubulointerstitial changes, and recurrent episodes of rhabdomyolysis. We outline mechanisms that may underlie the occurrence of chronic kidney disease in the setting of this novel mtDNA mutation. We also underscore the need to consider in relevant kidney diseases the presence of an underlying mitochondrial cytopathy because the latter more commonly exists than is generally recognized.
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http://dx.doi.org/10.1053/j.ajkd.2018.06.032DOI Listing
February 2019

Anesthetic Considerations for Angelman Syndrome: Case Series and Review of the Literature.

Anesth Pain Med 2017 Oct 26;7(5):e57826. Epub 2017 Jul 26.

Department of Anesthesiology and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA.

Background: Angelman syndrome is a rare neurodevelopmental disorder characterized by intellectual disability, severe speech impairment, ataxia, seizures, happy demeanor, distinctive craniofacial features, high vagal tone, and gamma-amino butyric acid receptor abnormalities. The aim of this report is to review our experience of patients with Angelman syndrome undergoing anesthetic management.

Methods: We retrospectively reviewed perioperative course of patients with Angelman syndrome who underwent procedures under anesthesia from 2000 to 2016.

Results: Six patients with Angelman syndrome underwent 18 procedures; 14 performed under general anesthesia, and 4 with monitored anesthetic care, many for minor procedures (e.g., dental and diagnostic). Five patients had profound developmental delay and were nonverbal and 4 of them had epilepsy. The perioperative courses were uncomplicated except a 2 year-old girl having an intraoperative bronchospasm, a 16 year-old girl requiring flumazenil administration, and 28 year-old man who was electively intubated with a videolaryngoscope because of airway management concerns. No patients were documented as having postoperative pain.

Conclusions: Angelman syndrome patients often require anesthesia for relatively innocuous procedures, and their speech impairment and happy demeanor can confound postoperative pain assessment. Patients can have atypical responses to benzodiazepines. Craniofacial abnormalities can complicate airway management. Although not encountered in this series, anesthesiologists need to be aware that Angelman syndrome patients have developed malignant bradydysrhythmias while anesthetized.
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http://dx.doi.org/10.5812/aapm.57826DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5903253PMC
October 2017

Phenotypic Variability of c.436delC DCAF17 Gene Mutation in Woodhouse-Sakati Syndrome.

Am J Case Rep 2018 Mar 25;19:347-353. Epub 2018 Mar 25.

Department of Clinical Genomics, Mayo Clinic, Rochester, MN, USA.

BACKGROUND Woodhouse-Sakati syndrome (WSS) is a rare autosomal recessive genetic condition that was first described in 1983. Since its original description, approximately 50 cases have been reported with various clinical signs and symptoms. Characteristics include progressive neurologic deterioration with extrapyramidal involvement and polyendocrinopathy most notable for hypogonadism starting in early adolescence. Clinical presentation is variable, and a subset of patients may have additional features, such as premature aging, alopecia, distinctive facial features, cognitive impairment, or deafness. CASE REPORT We illustrate the phenotypic variability of 5 patients with WSS due to the previously reported homozygous single nucleotide deletion c.436delC in the DCAF17 gene, identified in 2008. Despite identical genetic alteration, our 5 patients had various clinical features among them and compared with previously reported cases with the same pathogenic mutation. CONCLUSIONS The phenotypic variability of WSS due to c.436delC founder mutation may have a wider range than previously recognized.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5881453PMC
http://dx.doi.org/10.12659/ajcr.907395DOI Listing
March 2018

Novel GRN mutation presenting as an aphasic dementia and evolving into corticobasal syndrome.

Neurol Genet 2017 Dec 11;3(6):e201. Epub 2017 Dec 11.

Department of Neurology (H.B., R.C.P., D.S.K., B.F.B.), Department of Clinical Genomic and Neurology (R.H.G.), Department of Psychiatry and Psychology (M.A.M., J.A.F.), Department of Nuclear Medicine (V.J.W.), Department of Radiology (C.R.J.), and Alzheimer's Disease Research Center (C.M.D., D.J.G.), Mayo Clinic, Rochester, MN; and Department of Neuroscience (N.A.F., R.R.), Mayo Clinic, Jacksonville, FL.

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http://dx.doi.org/10.1212/NXG.0000000000000201DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5733247PMC
December 2017

Clinical spectrum and genotype-phenotype associations of KCNA2-related encephalopathies.

Brain 2017 Sep;140(9):2337-2354

Danish Epilepsy Centre, Dianalund, Denmark.

Recently, de novo mutations in the gene KCNA2, causing either a dominant-negative loss-of-function or a gain-of-function of the voltage-gated K+ channel Kv1.2, were described to cause a new molecular entity within the epileptic encephalopathies. Here, we report a cohort of 23 patients (eight previously described) with epileptic encephalopathy carrying either novel or known KCNA2 mutations, with the aim to detail the clinical phenotype associated with each of them, to characterize the functional effects of the newly identified mutations, and to assess genotype-phenotype associations. We identified five novel and confirmed six known mutations, three of which recurred in three, five and seven patients, respectively. Ten mutations were missense and one was a truncation mutation; de novo occurrence could be shown in 20 patients. Functional studies using a Xenopus oocyte two-microelectrode voltage clamp system revealed mutations with only loss-of-function effects (mostly dominant-negative current amplitude reduction) in eight patients or only gain-of-function effects (hyperpolarizing shift of voltage-dependent activation, increased amplitude) in nine patients. In six patients, the gain-of-function was diminished by an additional loss-of-function (gain-and loss-of-function) due to a hyperpolarizing shift of voltage-dependent activation combined with either decreased amplitudes or an additional hyperpolarizing shift of the inactivation curve. These electrophysiological findings correlated with distinct phenotypic features. The main differences were (i) predominant focal (loss-of-function) versus generalized (gain-of-function) seizures and corresponding epileptic discharges with prominent sleep activation in most cases with loss-of-function mutations; (ii) more severe epilepsy, developmental problems and ataxia, and atrophy of the cerebellum or even the whole brain in about half of the patients with gain-of-function mutations; and (iii) most severe early-onset phenotypes, occasionally with neonatal onset epilepsy and developmental impairment, as well as generalized and focal seizures and EEG abnormalities for patients with gain- and loss-of-function mutations. Our study thus indicates well represented genotype-phenotype associations between three subgroups of patients with KCNA2 encephalopathy according to the electrophysiological features of the mutations.
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http://dx.doi.org/10.1093/brain/awx184DOI Listing
September 2017

Cerebroretinal microangiopathy with calcifications and cysts (CRMCC) or "Coats Plus": when peripheral retinal vasculature signals neurologic disease.

J AAPOS 2017 Oct 31;21(5):420-422. Epub 2017 Aug 31.

Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota. Electronic address:

An 8-month-old girl presented with vitreous hemorrhage, peripheral retinal arteriovenous anastomosis, and hypoplasia of the thumb. Magnetic resonance imaging of the brain showed multiple hyperintensities, cysts, and calcifications in the white matter. DNA testing showed a mutation in one allele of the CTC gene, supporting the diagnosis of cerebroretinal microangiopathy with calcifications and cysts (CRMCC), or Coats plus disease, despite which designation this condition can present without subretinal exudate. In infants with peripheral retinal vascular disease, neuroimaging can identify the characteristic abnormalities of CRMCC.
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http://dx.doi.org/10.1016/j.jaapos.2017.04.015DOI Listing
October 2017

The prevalence of diseases caused by lysosome-related genes in a cohort of undiagnosed patients.

Mol Genet Metab Rep 2017 Dec 11;13:46-51. Epub 2017 Aug 11.

Center for Individualized Medicine, Health Sciences Research, Mayo Clinic, Rochester, MN, USA.

Lysosomal diseases (LD) comprise a group of approximately 60 hereditary conditions caused by progressive accumulation of metabolites due to defects in lysosomal enzymes and degradation pathways, which lead to a wide range of clinical manifestations. The estimated combined incidence of LD is between 1 in 4000 to 1 in 13,000 live births, with recent data from pilot newborn screening studies showing even higher incidence. We aimed to determine the prevalence of the classical LD and other diseases caused by lysosome-related genes in our cohort of diagnostic odyssey patients. The Individualized Medicine Clinic at Mayo Clinic is increasingly utilizing whole exome sequencing (WES) to determine the genetic etiology of undiagnosed Mendelian disease. From September 2012 to April 2017, WES results from 350 patients with unexplained symptoms were reviewed. Disease-causing variants were identified in , , , , and revealing a genetic diagnosis of a LD in 8 individuals from 5 families. Based on our findings, lysosome-related disorders may be collectively common, reaching up to 1.5% prevalence in a cohort of patients with undiagnosed diseases presenting to a genetics clinic.
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http://dx.doi.org/10.1016/j.ymgmr.2017.08.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5554961PMC
December 2017

Heterozygous variants in ACTL6A, encoding a component of the BAF complex, are associated with intellectual disability.

Hum Mutat 2017 10 10;38(10):1365-1371. Epub 2017 Jul 10.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.

Pathogenic variants in genes encoding components of the BRG1-associated factor (BAF) chromatin remodeling complex have been associated with intellectual disability syndromes. We identified heterozygous, novel variants in ACTL6A, a gene encoding a component of the BAF complex, in three subjects with varying degrees of intellectual disability. Two subjects have missense variants affecting highly conserved amino acid residues within the actin-like domain. Missense mutations in the homologous region in yeast actin were previously reported to be dominant lethal and were associated with impaired binding of the human ACTL6A to β-actin and BRG1. A third subject has a splicing variant that creates an in-frame deletion. Our findings suggest that the variants identified in our subjects may have a deleterious effect on the function of the protein by disturbing the integrity of the BAF complex. Thus, ACTL6A gene mutation analysis should be considered in patients with intellectual disability, learning disabilities, or developmental language disorder.
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http://dx.doi.org/10.1002/humu.23282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5599325PMC
October 2017

Multigenerational pedigree with STAR syndrome: A novel FAM58A variant and expansion of the phenotype.

Am J Med Genet A 2017 May 21;173(5):1328-1333. Epub 2017 Mar 21.

Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota.

STAR syndrome is a rare X-linked dominant disorder characterized by toe Syndactyly, Telecanthus, Anogenital malformations, and Renal malformations, and is caused by loss-of-function variants in FAM58A. Our proband presented with the hallmark features of STAR syndrome, as well as some additional less typical features including tethered cord and hearing loss. The proband's mother and maternal half-sister had similar clinical histories, but had variability in phenotypic severity. Clinical whole exome sequencing revealed a novel pathogenic nonsense variant, c.651G>A (p.Trp217X; NM_152274), in FAM58A in the proband, mother, and maternal half-sister. This pedigree represents the 11-13th patients described with STAR syndrome and the third instance of familial inheritance. To our knowledge, this is the first occurrence of a nonsense variant in FAM58A described in individuals with STAR syndrome and the phenotype in this pedigree suggests that tethered cord and hearing loss are features of STAR syndrome.
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http://dx.doi.org/10.1002/ajmg.a.38113DOI Listing
May 2017

De novo 2p16.1 microdeletion with metastatic esophageal adenocarcinoma.

BMJ Case Rep 2017 Jan 20;2017. Epub 2017 Jan 20.

Department of Primary Care Internal Medicine, Mayo Clinic Minnesota, Rochester, Minnesota, USA.

Microdeletions involving chromosome 2p15-16.1 are a rare genetic abnormality and have been reported in 18 separate patients, mainly children, since 2007. This microdeletion syndrome is characterised by a heterogeneous expression of intellectual impairment, dysmorphic facies, musculoskeletal abnormalities and potential neurodevelopmental anomalies. We report the first case of natural progression in an adult patient who died at a young age of metastatic esophageal adenocarcinoma. Important learning points include the variable phenotypic expression of this microdeletion syndrome and the fact that clinicians must be thorough in investigating objective discrepancies in patients who cannot endorse classical symptoms.
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http://dx.doi.org/10.1136/bcr-2016-218016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5256579PMC
January 2017

A Novel Kleefstra Syndrome-associated Variant That Affects the Conserved TPL Motif within the Ankyrin Repeat of EHMT1 Leads to Abnormal Protein Folding.

J Biol Chem 2017 03 5;292(9):3866-3876. Epub 2017 Jan 5.

the Department of Clinical Genomics,

Kleefstra syndrome (KS) (Mendelian Inheritance in Man (MIM) no. 610253), also known as 9q34 deletion syndrome, is an autosomal dominant disorder caused by haploinsufficiency of euchromatic histone methyltransferase-1 (). The clinical phenotype of KS includes moderate to severe intellectual disability with absent speech, hypotonia, brachycephaly, congenital heart defects, and dysmorphic facial features with hypertelorism, synophrys, macroglossia, protruding tongue, and prognathism. Only a few cases of missense mutations in giving rise to KS have been described. However, some variants have been described in individuals presenting with autism spectrum disorder or mild intellectual disability, suggesting that the phenotypic spectrum resulting from EHMT1 alterations may be quite broad. In this report, we describe two unrelated patients with complex medical histories consistent with KS in whom next generation sequencing identified the same novel c.2426C>T (p.P809L) missense variant in To examine the functional significance of this novel variant, we performed molecular dynamics simulations of the wild type and p.P809L variant, which predicted that the latter would have a propensity to misfold, leading to abnormal histone mark binding. Recombinant EHMT1 p.P809L was also studied using far UV circular dichroism spectroscopy and intrinsic protein fluorescence. These functional studies confirmed the model-based hypotheses and provided evidence for protein misfolding and aberrant target recognition as the underlying pathogenic mechanism for this novel KS-associated variant. This is the first report to suggest that missense variants in EHMT1 that lead to protein misfolding and disrupted histone mark binding can lead to KS.
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http://dx.doi.org/10.1074/jbc.M116.770545DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339767PMC
March 2017