Neurogenomics

Research

Cracking
the Code

Identifying the cause of neurological disorders and early intervention are key to reducing the devastating brain damage that can occur. 

Neurological disorders can be caused both by inherited and random gene variations. Often, the first sign of a disorder in a newborn is unexplained seizures. 

RCIGM is involved in both foundational and translational research.

Neurodevelopmental Genetics

RCIGM investigations into inherited brain disorders focus on poorly understood conditions in neuronal development where the application of human genetics, wet-lab disease modeling and cell biology can be used to develop new treatments.
190227RadySeminar

Joseph Gleeson, MD

RCIGM Director of Neurodevelopmental Genetics Endowed Chair

Joseph Gleeson, MD, is the RCIGM Director of Neurodevelopmental Genetics Endowed Chair. Among his current research projects is a genetic investigation of the genetic mechanisms underlying spina bifida, the most common structural defect of the central nervous system.

In 2020 Dr. Gleeson along with other researchers at UC San Diego School of Medicine, in collaboration with Rady Children’s Institute for Genomic Medicine, were awarded an $8.3 million grant from the National Institutes of Health’s Eunice Kennedy Shriver National Institute of Child Health and Human Development to further illuminate the causes of spina bifida.

Dr. Gleeson also heads the Neurogenetics Laboratory at UC San Diego and is the Director of the Center for Brain Development. He is the 2020 recipient of the Bernard Sachs Award from the Child Neurology Society. In 2017, he was the first recipient of the Constance Lieber Prize for Innovation in Developmental Neuroscience.

Publications

Genome Sequencing for Diagnosing Rare Diseases

  • Wojcik MH, Lemire G, Berger E, Zaki MS, Wissmann M, Win W, White SM, Weisburd B, Wieczorek D, Waddell LB, Verboon JM, VanNoy GE, Töpf A, Tan TY, Syrbe S, Strehlow V, Straub V, Stenton SL, Snow H, Singer-Berk M, Silver J, Shril S, Seaby EG, Schneider R, Sankaran VG, Sanchis-Juan A, Russell KA, Reinson K, Ravenscroft G, Radtke M, Popp D, Polster T, Platzer K, Pierce EA, Place EM, Pajusalu S, Pais L, Õunap K, Osei-Owusu I, Opperman H, Okur V, Oja KT, O'Leary M, O'Heir E, Morel CF, Merkenschlager A, Marchant RG, Mangilog BE, Madden JA, MacArthur D, Lovgren A, Lerner-Ellis JP, Lin J, Laing N, Hildebrandt F, Hentschel J, Groopman E, Goodrich J, Gleeson JG, Ghaoui R, Genetti CA, Gburek-Augustat J, Gazda HT, Ganesh VS, Ganapathi M, Gallacher L, Fu JM, Evangelista E, England E, Donkervoort S, DiTroia S, Cooper ST, Chung WK, Christodoulou J, Chao KR, Cato LD, Bujakowska KM, Bryen SJ, Brand H, Bönnemann CG, Beggs AH, Baxter SM, Bartolomaeus T, Agrawal PB, Talkowski M, Austin-Tse C, Abou Jamra R, Rehm HL, O'Donnell-Luria A.

N Engl J Med. 2024 Jun 6;390(21):1985-1997. doi: 10.1056/NEJMoa2314761.

ABSTRACT

BACKGROUND: Genetic variants that cause rare disorders may remain elusive even after expansive testing, such as exome sequencing. The diagnostic yield of genome sequencing, particularly after a negative evaluation, remains poorly defined.

METHODS: We sequenced and analyzed the genomes of families with diverse phenotypes who were suspected to have a rare monogenic disease and for whom genetic testing had not revealed a diagnosis, as well as the genomes of a replication cohort at an independent clinical center.

RESULTS: We sequenced the genomes of 822 families (744 in the initial cohort and 78 in the replication cohort) and made a molecular diagnosis in 218 of 744 families (29.3%). Of the 218 families, 61 (28.0%) – 8.2% of families in the initial cohort – had variants that required genome sequencing for identification, including coding variants, intronic variants, small structural variants, copy-neutral inversions, complex rearrangements, and tandem repeat expansions. Most families in which a molecular diagnosis was made after previous nondiagnostic exome sequencing (63.5%) had variants that could be detected by reanalysis of the exome-sequence data (53.4%) or by additional analytic methods, such as copy-number variant calling, to exome-sequence data (10.8%). We obtained similar results in the replication cohort: in 33% of the families in which a molecular diagnosis was made, or 8% of the cohort, genome sequencing was required, which showed the applicability of these findings to both research and clinical environments.

CONCLUSIONS: The diagnostic yield of genome sequencing in a large, diverse research cohort and in a small clinical cohort of persons who had previously undergone genetic testing was approximately 8% and included several types of pathogenic variation that had not previously been detected by means of exome sequencing or other techniques. (Funded by the National Human Genome Research Institute and others.).

PMID:38838312 | DOI:10.1056/NEJMoa2314761

Frontiers in congenital disorders of glycosylation consortium, a cross-sectional study report at year 5 of 280 individuals in the natural history cohort

  • Lam C, Scaglia F, Berry GT, Larson A, Sarafoglou K, Andersson HC, Sklirou E, Tan QKG, Starosta RT, Sadek M, Wolfe L, Horikoshi S, Ali M, Barone R, Campbell T, Chang IJ, Coles K, Cook E, Eklund EA, Engelhardt NM, Freeman M, Friedman J, Fu DYT, Botzo G, Rawls B, Hernandez C, Johnsen C, Keller K, Kramer S, Kuschel B, Leshinski A, Martinez-Duncker I, Mazza GL, Mercimek-Andrews S, Miller BS, Muthusamy K, Neira J, Patterson MC, Pogorelc N, Powers LN, Ramey E, Reinhart M, Squire A, Thies J, Vockley J, Vreugdenhil H, Witters P, Youbi M, Zeighami A, Zemet R, Edmondson AC, Morava E. Frontiers in congenital disorders of glycosylation consortium, a cross-sectional study report at year 5 of 280 individuals in the natural history cohort. Mol Genet Metab. 2024 Aug;142(4):108509. doi: 10.1016/j.ymgme.2024.108509. Epub 2024 Jun 6. PMID: 38959600; PMCID: PMC11299528.

Mol Genet Metab. 2024 Jun 6;142(4):108509. doi: 10.1016/j.ymgme.2024.108509. Online ahead of print.

ABSTRACT

OBJECTIVE: Our report describes clinical, genetic, and biochemical features of participants with a molecularly confirmed congenital disorder of glycosylation (CDG) enrolled in the Frontiers in Congenital Disorders of Glycosylation (FCDGC) Natural History cohort at year 5 of the study.

METHODS: We enrolled individuals with a known or suspected CDG into the FCDGC Natural History Study, a multicenter prospective and retrospective natural history study of all genetic causes of CDG. We conducted a cross-sectional analysis of baseline study visit data from participants with confirmed CDG who were consented into the FCDGC Natural History Study (5U54NS115198) from October 2019 to November 2023.

RESULTS: Three hundred thirty-three subjects consented to the FCDGC Natural History Study. Of these, 280 unique individuals had genetic data available that was consistent with a diagnosis of CDG. These 280 individuals were enrolled into the study between October 8, 2019 and November 29, 2023. One hundred forty-one (50.4%) were female, and 139 (49.6%) were male. Mean and median age at enrollment was 10.1 and 6.5 years, respectively, with a range of 0.22 to 71.4 years. The cohort encompassed individuals with disorders of N-linked protein glycosylation (57%), glycosylphosphatidylinositol anchor disorder (GPI anchor) (15%), disorders of Golgi homeostasis, trafficking and transport (12%), dolichol metabolism disorders (5%), disorders of multiple pathways (6%), and other (5%). The most frequent presenting symptom(s) leading to diagnosis were developmental delay/disability (77%), followed by hypotonia (56%) and feeding difficulties (42%). Mean and median time between first related symptom and diagnosis was 2.7 and 0.8 years, respectively. One hundred percent of individuals in our cohort had developmental differences/disabilities at the time of their baseline visit, followed by 97% with neurologic involvement, 91% with gastrointestinal (GI)/liver involvement, and 88% with musculoskeletal involvement. Severity of disease in individuals was scored on the Nijmegen Progression CDG Rating Scale (NPCRS) with 27% of scores categorized as mild, 44% moderate, and 29% severe. Of the individuals with N-linked protein glycosylation defects, 83% of those with data showed a type 1 pattern on carbohydrate deficient transferrin (CDT) analysis including 82/84 individuals with PMM2-CDG, 6% a type 2 pattern, 1% both type 1 and type 2 pattern and 10% a normal or nonspecific pattern. One hundred percent of individuals with Golgi homeostasis and trafficking defects with data showed a type 2 pattern on CDT analysis, while Golgi transport defect showed a type II pattern 73% of the time, a type 1 pattern for 7%, and 20% had a normal or nonspecific pattern. Most of the variants documented were classified as pathogenic or likely pathogenic using ACMG criteria. For the majority of the variants, the predicted molecular consequence was missense followed by nonsense and splice site, and the majority of the diagnoses are inherited in an autosomal recessive pattern but with disorders of all major nuclear inheritance included.

DISCUSSION: The FCDGC Natural History Study serves as an important resource to build future research studies, improve clinical care, and prepare for clinical trial readiness. Herein is the first overview of CDG participants of the FCDGC Natural History Study.

PMID:38959600 | DOI:10.1016/j.ymgme.2024.108509

The contribution of de novo coding mutations to meningomyelocele

  • Yoo-Jin Ha, Isaac Tang, Ashna Nisal, Ishani Jhamb, Cassidy Wallace, Sarah Schroeder, Chanjae Lee, Keng loi Vong, Naomi Meave, Fiza Jiwani, Chelsea Barrows, Sangmoon Lee, Nan Jiang, Arzoo Patel, Francisco A. Blanco, Seyoung Yu, Hui Su Jeong, Isaac Plutzer, Michael B. Major, Béatrice Benoit, Christian Poüs, Caleb Heffner, Zoha Kibar, Gyang Markus Bot, Hope Northrup, Kit Sing Au, Madison Strain, Allison Ashley-Koch, Richard H. Finnell, Joan T. Le, Hal Meltzer, Camila Araujo, Helio R. Machado, Roger E. Stevenson, Anna Yurrita, Sara Mumtaz, Osvaldo M. Mutchinick, José Ramón Medina-Bereciartu, Friedhelm Hildebrandt, Gia Melikishvili, Rony Marwan, Valeria Capra, Mahmoud M. Noureldeen, Aida M.S. Salem, Mahmoud Y. Issa, Maha S. Zaki, Ji Eun Lee, Anna Alkelai, Alan R. Shuldiner, Stephen F. Kingsmore, Stephen A. Murray, Heon Yung Gee, W. Todd Miller, Kimberley F. Tolias, John B. Wallingford, Spina Bifida Sequencing Consortium, Sangwoo Kim, Joseph G. Gleeson

medRxiv, March 2, 2024.

ABSTRACT
Meningomyelocele (MM) is considered a genetically complex disease resulting from failure of neural tube closure (NTD). Patients display neuromotor disability and frequent hydrocephalus requiring ventricular shunting. A few proposed genes contribute to disease susceptibility, but most risk remains unexplained. We postulated that de novo mutations (DNMs) under purifying selection contribute to MM risk. Here we recruited a cohort of 851 MM trios requiring shunting at birth, compared with 732 control trios, and found that de novo likely gene disrupting or damaging missense mutations occur in approximately 22.3% of subjects, 28% of which are estimated to contribute to disease risk. The 187 genes with damaging DNMs collectively define networks including actin cytoskeleton and microtubule-based processes, axon guidance, and histone modification. Gene validation demonstrates partial or complete loss of function, impaired signaling and defective neural tube closure in Xenopus embryos. Our results suggest DNMs make key contributions to MM risk, and highlight critical pathways required for neural tube closure in human embryogenesis.

DOI:10.1101/2024.02.28.24303390

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Genetic Neurologic Disease

Neurologic Movement Disorders

RCIGM focuses on translational research in pediatric neurologic movement disorders, particularly those resulting from genetic or metabolic conditions. 

Investigations into genetic underpinnings of neurologic movement disorders is led by Jennifer Friedman, MD. Her work involves sequencing children with unexplained neurologic disease to identify diagnosis and treatment options.

Dr. Friedman’s research is aimed at ending the diagnostic odyssey by bringing diagnoses to patients and families; shortening the therapeutic odyssey by delivering precision neurologic care and identifying novel genes for rare neurologic disorders.

headshot of Dr. Jenni Friedman

Jennifer Friedman, MD

Dr. Jennifer Friedman is the Translational Medicine Director for the Precision Medicine Clinic at Rady Children’s Hospital, where she is also a senior staff neurologist. In addition, she serves as clinical professor in the UC San Diego Departments of Neurosciences and Pediatrics. 

Dr. Friedman is a diplomate of the American Board of Psychiatry and Neurology. She is a member of the American Academy of Neurology, the Movement Disorder Society, the Tourette Syndrome Association, and the Phi Beta Kappa National Honor Society. 

Publications

MSL2 variants lead to a neurodevelopmental syndrome with lack of coordination, epilepsy, specific dysmorphisms, and a distinct episignature

  • Karayol R, Borroto MC, Haghshenas S, Namasivayam A, Reilly J, Levy MA, Relator R, Kerkhof J, McConkey H, Shvedunova M, Petersen AK, Magnussen K, Zweier C, Vasileiou G, Reis A, Savatt JM, Mulligan MR, Bicknell LS, Poke G, Abu-El-Haija A, Duis J, Hannig V, Srivastava S, Barkoudah E, Hauser NS, van den Born M, Hamiel U, Henig N, Baris Feldman H, McKee S, Krapels IPC, Lei Y, Todorova A, Yordanova R, Atemin S, Rogac M, McConnell V, Chassevent A, Barañano KW, Shashi V, Sullivan JA, Peron A, Iascone M, Canevini MP, Friedman J, Reyes IA, Kierstein J, Shen JJ, Ahmed FN, Mao X, Almoguera B, Blanco-Kelly F, Platzer K, Treu AB, Quilichini J, Bourgois A, Chatron N, Januel L, Rougeot C, Carere DA, Monaghan KG, Rousseau J, Myers KA, Sadikovic B, Akhtar A, Campeau PM. MSL2 variants lead to a neurodevelopmental syndrome with lack of coordination, epilepsy, specific dysmorphisms, and a distinct episignature. Am J Hum Genet. 2024 Jul 11;111(7):1330-1351. doi: 10.1016/j.ajhg.2024.05.001. Epub 2024 May 29. PMID: 38815585; PMCID: PMC11267526.

Am J Hum Genet. 2024 May 28:S0002-9297(24)00164-2. doi: 10.1016/j.ajhg.2024.05.001. Online ahead of print.

ABSTRACT

Epigenetic dysregulation has emerged as an important etiological mechanism of neurodevelopmental disorders (NDDs). Pathogenic variation in epigenetic regulators can impair deposition of histone post-translational modifications leading to aberrant spatiotemporal gene expression during neurodevelopment. The male-specific lethal (MSL) complex is a prominent multi-subunit epigenetic regulator of gene expression and is responsible for histone 4 lysine 16 acetylation (H4K16ac). Using exome sequencing, here we identify a cohort of 25 individuals with heterozygous de novo variants in MSL complex member MSL2. MSL2 variants were associated with NDD phenotypes including global developmental delay, intellectual disability, hypotonia, and motor issues such as coordination problems, feeding difficulties, and gait disturbance. Dysmorphisms and behavioral and/or psychiatric conditions, including autism spectrum disorder, and to a lesser extent, seizures, connective tissue disease signs, sleep disturbance, vision problems, and other organ anomalies, were observed in affected individuals. As a molecular biomarker, a sensitive and specific DNA methylation episignature has been established. Induced pluripotent stem cells (iPSCs) derived from three members of our cohort exhibited reduced MSL2 levels. Remarkably, while NDD-associated variants in two other members of the MSL complex (MOF and MSL3) result in reduced H4K16ac, global H4K16ac levels are unchanged in iPSCs with MSL2 variants. Regardless, MSL2 variants altered the expression of MSL2 targets in iPSCs and upon their differentiation to early germ layers. Our study defines an MSL2-related disorder as an NDD with distinguishable clinical features, a specific blood DNA episignature, and a distinct, MSL2-specific molecular etiology compared to other MSL complex-related disorders.

PMID:38815585 | DOI:10.1016/j.ajhg.2024.05.001

Sunflower Syndrome: A Survey of Provider Awareness and Management Preferences

  • Baumer FM, Julich K, Friedman J, Nespeca M, Thiele EA, Bhatia S, Joshi C.

Pediatr Neurol. 2023 Nov 30;152:177-183. doi: 10.1016/j.pediatrneurol.2023.11.013. Online ahead of print.

ABSTRACT

BACKGROUND: Sunflower syndrome is a rare photosensitive pediatric epilepsy characterized by stereotyped hand-waving in response to bright lights. These stereotyped movements with maintained awareness can be mistaken for a movement disorder. This study assessed neurology providers’ diagnostic reasoning, evaluation, and treatment of Sunflower syndrome.

METHODS: A 32-question anonymized electronic survey, including a clinical vignette and video of hand-waving in sunlight, was distributed to child neurology providers to assess (1) initial diagnosis and evaluation based on clinical information, (2) updated diagnosis and management after electroencephalography (EEG), and (3) prior experience with Sunflower syndrome.

RESULTS: Among 277 viewed surveys, 211 respondents provided information about initial diagnosis and evaluation, 200 about updated diagnosis, 191 about management, and 189 about prior clinical experience. Most providers (135, 64%) suspected seizure, whereas fewer suspected movement disorders (29, 14%) or were unsure of the diagnosis (37, 22%). EEG was recommended by 180 (85%). After EEG, 189 (95%) diagnosed epilepsy, 111 of whom specifically diagnosed Sunflower syndrome. The majority (149, 78%) recommended antiseizure medications (ASMs) and sun avoidance (181, 95%). Only 103 (55%) had managed Sunflower syndrome. Epileptologists and those with prior clinical experience were more likely to suspect a seizure, order an EEG, and offer ASMs than those without prior experience.

CONCLUSIONS: Although many providers had not managed Sunflower syndrome, the majority recognized this presentation as concerning for epilepsy. Epilepsy training and prior clinical experience are associated with improved recognition and appropriate treatment. Educational initiatives that increase awareness of Sunflower syndrome may improve patient care.

PMID:38295719 | DOI:10.1016/j.pediatrneurol.2023.11.013

ARF1-related disorder: phenotypic and molecular spectrum

  • de Sainte Agathe JM, Pode-Shakked B, Naudion S, Michaud V, Arveiler B, Fergelot P, Delmas J, Keren B, Poirsier C, Alkuraya FS, Tabarki B, Bend E, Davis K, Bebin M, Thompson ML, Bryant EM, Wagner M, Hannibal I, Lenberg J, Krenn M, Wigby KM, Friedman JR, Iascone M, Cereda A, Miao T, LeGuern E, Argilli E, Sherr E, Caluseriu O, Tidwell T, Bayrak-Toydemir P, Hagedorn C, Brugger M, Vill K, Morneau-Jacob FD, Chung W, Weaver KN, Owens JW, Husami A, Chaudhari BP, Stone BS, Burns K, Li R, de Lange IM, Biehler M, Ginglinger E, Gérard B, Stottmann RW, Trimouille A.

J Med Genet. 2023 Apr 25:jmg-2022-108803. doi: 10.1136/jmg-2022-108803. Online ahead of print.

ABSTRACT

PURPOSE: ARF1 was previously implicated in periventricular nodular heterotopia (PVNH) in only five individuals and systematic clinical characterisation was not available. The aim of this study is to provide a comprehensive description of the phenotypic and genotypic spectrum of ARF1-related neurodevelopmental disorder.

METHODS: We collected detailed phenotypes of an international cohort of individuals (n=17) with ARF1 variants assembled through the GeneMatcher platform. Missense variants were structurally modelled, and the impact of several were functionally validated.

RESULTS: De novo variants (10 missense, 1 frameshift, 1 splice altering resulting in 9 residues insertion) in ARF1 were identified among 17 unrelated individuals. Detailed phenotypes included intellectual disability (ID), microcephaly, seizures and PVNH. No specific facial characteristics were consistent across all cases, however microretrognathia was common. Various hearing and visual defects were recurrent, and interestingly, some inflammatory features were reported. MRI of the brain frequently showed abnormalities consistent with a neuronal migration disorder.

CONCLUSION: We confirm the role of ARF1 in an autosomal dominant syndrome with a phenotypic spectrum including severe ID, microcephaly, seizures and PVNH due to impaired neuronal migration.

PMID:37185208 DOI:10.1136/jmg-2022-108803

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Discovery of Endocannabinoid Gene Mutation Leads to Identification of  New, Rare Pediatric Neurological Disease

In a study published in the October 2022 issue of BRAIN, researchers from Rady Children’s Institute for Genomic Medicine (RCIGM®) and the University of California San Diego School of Medicine describe their discovery of a new clinical syndrome, Neuro-Ocular DAGLA-related Syndrome (NODRS), in children with termination variants in the diacylglycerol lipase alpha (DAGLA) gene which encodes an enzyme in the brain that is involved in the signaling pathway of the endocannabinoid (eCB) system.

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