1
|
Sen K, Izem R, Long Y, Jiang J, Konczal LL, McCarter RJ, Gropman AL, Bedoyan JK. Are asymptomatic carriers of OTC deficiency always asymptomatic? A multicentric retrospective study of risk using the UCDC longitudinal study database. Mol Genet Genomic Med 2024; 12:e2443. [PMID: 38634223 PMCID: PMC11024633 DOI: 10.1002/mgg3.2443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 03/24/2024] [Accepted: 04/02/2024] [Indexed: 04/19/2024] Open
Abstract
BACKGROUND Ornithine transcarbamylase deficiency (OTCD) due to an X-linked OTC mutation, is responsible for moderate to severe hyperammonemia (HA) with substantial morbidity and mortality. About 80% of females with OTCD remain apparently "asymptomatic" with limited studies of their clinical characteristics and long-term health vulnerabilities. Multimodal neuroimaging studies and executive function testing have shown that asymptomatic females exhibit limitations when stressed to perform at higher cognitive load and had reduced activation of the prefrontal cortex. This retrospective study aims to improve understanding of factors that might predict development of defined complications and serious illness in apparent asymptomatic females. A proband and her daughter are presented to highlight the utility of multimodal neuroimaging studies and to underscore that asymptomatic females with OTCD are not always asymptomatic. METHODS We review data from 302 heterozygote females with OTCD enrolled in the Urea Cycle Disorders Consortium (UCDC) longitudinal natural history database. We apply multiple neuroimaging modalities in the workup of a proband and her daughter. RESULTS Among the females in the database, 143 were noted as symptomatic at baseline (Sym). We focused on females who were asymptomatic (Asx, n = 111) and those who were asymptomatic initially upon enrollment in study but who later became symptomatic sometime during follow-up (Asx/Sym, n = 22). The majority of Asx (86%) and Asx/Sym (75%) subjects did not restrict protein at baseline, and ~38% of Asx and 33% of Asx/Sym subjects suffered from mild to severe neuropsychiatric conditions such as mood disorder and sleep problems. The risk of mild to severe HA sometime later in life for the Asx and Asx/Sym subjects as a combined group was ~4% (5/133), with ammonia ranging from 77 to 470 μM and at least half (2/4) of subjects requiring hospital admission and nitrogen scavenger therapy. For this combined group, the median age of first HA crisis was 50 years, whereas the median age of first symptom which included neuropsychiatric and/or behavioral symptoms was 17 years. The multimodal neuroimaging studies in female heterozygotes with OTCD also underscore that asymptomatic female heterozygotes with OTCD (e.g., proband) are not always asymptomatic. CONCLUSIONS Analysis of Asx and Asx/Sym females with OTCD in this study suggests that future evidence-based management guidelines and/or a clinical risk score calculator for this cohort could be useful management tools to reduce morbidity and improve long-term quality of life.
Collapse
Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Neurodevelopmental PediatricsChildren's National Hospital, The George Washington School of MedicineWashingtonDCUSA
| | - Rima Izem
- Center for Translational Sciences, Children's National HospitalThe George Washington UniversityWashingtonDCUSA
- Children's National HospitalWashingtonDCUSA
| | - Yuelin Long
- Columbia University Mailman School of Public HealthNew YorkNew YorkUSA
| | - Jiji Jiang
- Center for Translational Sciences, Children's National HospitalThe George Washington UniversityWashingtonDCUSA
- Children's National HospitalWashingtonDCUSA
| | - Laura L. Konczal
- Center for Human Genetics, University Hospitals Cleveland Medical Center, Department of Genetics and Genome SciencesCase Western Reserve University School of MedicineClevelandOhioUSA
| | - Robert J. McCarter
- Center for Translational Sciences, Children's National HospitalThe George Washington UniversityWashingtonDCUSA
- Children's National HospitalWashingtonDCUSA
| | - Andrea L. Gropman
- Division of Neurogenetics and Neurodevelopmental PediatricsChildren's National Hospital, The George Washington School of MedicineWashingtonDCUSA
- Center for Translational Sciences, Children's National HospitalThe George Washington UniversityWashingtonDCUSA
| | - Jirair K. Bedoyan
- Division of Genetic and Genomic Medicine, Department of PediatricsUPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of MedicinePittsburghPennsylvaniaUSA
| |
Collapse
|
2
|
Khaksari K, Chen WL, Gropman AL. Review of Applications of Near-Infrared Spectroscopy in Two Rare Disorders with Executive and Neurological Dysfunction: UCD and PKU. Genes (Basel) 2022; 13:genes13101690. [PMID: 36292574 PMCID: PMC9602148 DOI: 10.3390/genes13101690] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/12/2022] [Accepted: 09/16/2022] [Indexed: 11/16/2022] Open
Abstract
Studying rare diseases, particularly those with neurological dysfunction, is a challenge to researchers and healthcare professionals due to their complexity and small population with geographical dispersion. Universal and standardized biomarkers generated by tools such as functional neuroimaging have been forged to collect baseline data as well as treatment effects. However, the cost and heavily infrastructural requirement of those technologies have substantially limited their availability. Thus, developing non-invasive, portable, and inexpensive modalities has become a major focus for both researchers and clinicians. When considering neurological disorders and diseases with executive dysfunction, EEG is the most convenient tool to obtain biomarkers which can correlate the objective severity and clinical observation of these conditions. However, studies have also shown that EEG biomarkers and clinical observations alone are not sensitive enough since not all the patients present classical phenotypical features or EEG evidence of dysfunction. This article reviews disorders, including two rare disorders with neurological dysfunction and the usefulness of functional near-infrared spectroscopy (fNIRS) as a non-invasive optical modality to obtain hemodynamic biomarkers of diseases and for screening and monitoring the disease.
Collapse
Affiliation(s)
- Kosar Khaksari
- Division of Neurogenetics and Developmental Pediatrics, Children’s National Health System, Washington, DC 20010, USA
- Correspondence:
| | - Wei-Liang Chen
- School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Andrea L. Gropman
- Division of Neurogenetics and Developmental Pediatrics, Children’s National Health System, Washington, DC 20010, USA
- Department of Neurology, George Washington University, Washington, DC 20052, USA
| |
Collapse
|
3
|
Sen K, Whitehead M, Castillo Pinto C, Caldovic L, Gropman A. Fifteen years of urea cycle disorders brain research: Looking back, looking forward. Anal Biochem 2022; 636:114343. [PMID: 34637785 PMCID: PMC8671367 DOI: 10.1016/j.ab.2021.114343] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/13/2021] [Accepted: 08/17/2021] [Indexed: 01/03/2023]
Abstract
Urea cycle disorders (UCD) are inherited diseases resulting from deficiency in one of six enzymes or two carriers that are required to remove ammonia from the body. UCD may be associated with neurological damage encompassing a spectrum from asymptomatic/mild to severe encephalopathy, which results in most cases from Hyperammonemia (HA) and elevation of other neurotoxic intermediates of metabolism. Electroencephalography (EEG), Magnetic resonance imaging (MRI) and Proton Magnetic resonance spectroscopy (MRS) are noninvasive measures of brain function and structure that can be used during HA to guide management and provide prognostic information, in addition to being research tools to understand the pathophysiology of UCD associated brain injury. The Urea Cycle Rare disorders Consortium (UCDC) has been invested in research to understand the immediate and downstream effects of hyperammonemia (HA) on brain using electroencephalogram (EEG) and multimodal brain MRI to establish early patterns of brain injury and to track recovery and prognosis. This review highlights the evolving knowledge about the impact of UCD and HA in particular on neurological injury and recovery and use of EEG and MRI to study and evaluate prognostic factors for risk and recovery. It recognizes the work of others and discusses the UCDC's prior work and future research priorities.
Collapse
Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Children's National Hospital, Washington D.C., United States
| | - Matthew Whitehead
- Division of Radiology, Children's National Hospital, Washington D.C., United States
| | | | - Ljubica Caldovic
- Childrens' Research Institute, Children's National Hospital, Washington D.C., United States
| | - Andrea Gropman
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Children's National Hospital, Washington D.C., United States.
| |
Collapse
|
4
|
Castillo-Pinto C, Sen K, Gropman A. Neuromonitoring in Rare Disorders of Metabolism. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2021; 94:645-655. [PMID: 34970103 PMCID: PMC8686771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inborn errors of metabolism (IEM) are a unique class of genetic diseases due to mutations in genes involved in key metabolic pathways. The combined incidence of IEM has been estimated to be as high as 1:1000. Urea Cycle disorders (UCD), one class of IEM, can present with cerebral edema and represent a possible target to explore the utility of different neuromonitoring techniques during an hyperammonemic crisis. The last two decades have brought advances in the early identification and comprehensive management of UCD, including further understanding of neuroimaging patterns associated with neurocognitive function. Nonetheless, very important questions remain about the potential acute neurotoxic effects of hyperammonemia to better understand how to treat and prevent secondary brain injury. In this review, we describe existing neuromonitoring techniques that have been used in rare metabolic disorders to assess and allow amelioration of ongoing brain injury. Directions of future research should be focused on identifying new diagnostic approaches in the management of metabolic crises to optimize care and reduce long term morbidity and mortality in patients with IEM.
Collapse
Affiliation(s)
| | - Kuntal Sen
- Neurogenetics and Neurodevelopmental Pediatrics, Children's National, Washington DC, USA
| | - Andrea Gropman
- Neurogenetics and Neurodevelopmental Pediatrics, Children's National, Washington DC, USA
| |
Collapse
|
5
|
Sen K, Anderson AA, Whitehead MT, Gropman AL. Review of Multi-Modal Imaging in Urea Cycle Disorders: The Old, the New, the Borrowed, and the Blue. Front Neurol 2021; 12:632307. [PMID: 33995244 PMCID: PMC8113618 DOI: 10.3389/fneur.2021.632307] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/26/2021] [Indexed: 12/16/2022] Open
Abstract
The urea cycle disorders (UCD) are rare genetic disorder due to a deficiency of one of six enzymes or two transport proteins that act to remove waste nitrogen in form of ammonia from the body. In this review, we focus on neuroimaging studies in OTCD and Arginase deficiency, two of the UCD we have extensively studied. Ornithine transcarbamylase deficiency (OTCD) is the most common of these, and X-linked. Hyperammonemia (HA) in OTCD is due to deficient protein handling. Cognitive impairments and neurobehavioral disorders have emerged as the major sequelae in Arginase deficiency and OTCD, especially in relation to executive function and working memory, impacting pre-frontal cortex (PFC). Clinical management focuses on neuroprotection from HA, as well as neurotoxicity from other known and yet unclassified metabolites. Prevention and mitigation of neurological injury is a major challenge and research focus. Given the impact of HA on neurocognitive function of UCD, neuroimaging modalities, especially multi-modality imaging platforms, can bring a wealth of information to understand the neurocognitive function and biomarkers. Such information can further improve clinical decision making, and result in better therapeutic interventions. In vivo investigations of the affected brain using multimodal neuroimaging combined with clinical and behavioral phenotyping hold promise. MR Spectroscopy has already proven as a tool to study biochemical aberrations such as elevated glutamine surrounding HA as well as to diagnose partial UCD. Functional Near Infrared Spectroscopy (fNIRS), which assesses local changes in cerebral hemodynamic levels of cortical regions, is emerging as a non-invasive technique and will serve as a surrogate to fMRI with better portability. Here we review two decades of our research using non-invasive imaging and how it has contributed to an understanding of the cognitive effects of this group of genetic conditions.
Collapse
Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Department of Neurology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| | - Afrouz A Anderson
- Department of Research, Focus Foundation, Crofton, MD, United States
| | - Matthew T Whitehead
- Department of Radiology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| | - Andrea L Gropman
- Division of Neurogenetics and Neurodevelopmental Pediatrics, Department of Neurology, Children's National Hospital, George Washington University School of Medicine, Washington, DC, United States
| |
Collapse
|
6
|
Anderson AA, Gropman A, Le Mons C, Stratakis CA, Gandjbakhche AH. Hemodynamics of Prefrontal Cortex in Ornithine Transcarbamylase Deficiency: A Twin Case Study. Front Neurol 2020; 11:809. [PMID: 32922350 PMCID: PMC7456944 DOI: 10.3389/fneur.2020.00809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 06/29/2020] [Indexed: 11/30/2022] Open
Abstract
Ornithine transcarbamylase deficiency (OTCD) is the most common form of urea cycle disorder characterized by the presence of hyperammonemia (HA). In patients with OTCD, HA is known to cause impairments in domains of executive function and working memory. Monitoring OTCD progression and investigating neurocognitive biomarkers can, therefore, become critical in understanding the underlying brain function in a population with OTCD. We used functional near infrared spectroscopy (fNIRS) to examine the hemodynamics of prefrontal cortex (PFC) in a fraternal twin with and without OTCD. fNIRS is a non-invasive and wearable optical technology that can be used to assess cortical hemodynamics in a realistic clinical setting. We quantified the hemodynamic variations in total-hemoglobin as assessed by fNIRS while subjects performed the N-back working memory (WM) task. Our preliminary results showed that the sibling with OTCD had higher variation in a very low frequency band (<0.03 Hz, related to mechanism of cerebral autoregulation) compared to the control sibling. The difference between these variations was not as prominent in the higher frequency band, indicating the possible role of impaired autoregulation and cognitive function due to presence of HA. We further examined the functional connectivity in PFC, where the OTCD sibling showed lower interhemispheric functional connectivity as the task load increased. Our pilot results are the first to show the utility of fNIRS in monitoring OTCD cortical hemodynamics, indicating the possibility of inefficient neurocognitive function. This study provides a novel insight into the monitoring of OTCD focusing on the contribution of physiological process and neurocognitive function in this population.
Collapse
Affiliation(s)
- Afrouz A. Anderson
- National Institutes of Health (NIH), National Institute of Child Health and Human Development, Bethesda, MD, United States
| | - Andrea Gropman
- Children's National Medical Center, Division of Neurogenetics and Neurodevelopmental Pediatrics, Washington, DC, United States
| | - Cynthia Le Mons
- National Urea Cycle Disorders Foundation, Pasadena, CA, United States
| | - Constantine A. Stratakis
- National Institutes of Health (NIH), National Institute of Child Health and Human Development, Bethesda, MD, United States
| | - Amir H. Gandjbakhche
- National Institutes of Health (NIH), National Institute of Child Health and Human Development, Bethesda, MD, United States
| |
Collapse
|
7
|
Sen K, Whitehead MT, Gropman AL. Multimodal imaging in urea cycle-related neurological disease - What can imaging after hyperammonemia teach us? ACTA ACUST UNITED AC 2020; 5:87-95. [PMID: 33344172 PMCID: PMC7739971 DOI: 10.3233/trd-200048] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Urea cycle-related brain disease may take on variable neuroimaging manifestations, ranging from normal to abnormal with or without a signature appearance. In the past, we have described the usefulness of multimodal imaging in identifying biomarkers of neuronal injury in UCD patients. In this study, we report unique findings in an adolescent male with neonatal-onset OTC deficiency after an episode of hyperammonemia. MATERIALS AND METHODS Multiplanar, multisequence MR imaging (T1WI, T2WI, T2 FLAIR, diffusion weighted images and gradient echo) of the brain was performed on seven separate occasions over the course following the acute illness; first five exams were performed within 28 days of admission and the final two exams were performed approximately 3 and 5 months later. RESULTS 1.The initial MR revealed increased signal on T2WI in the basal ganglia, claustrum and frontoparietal white matter; which remained stable over time. By the 5th exam, signal changes had developed in frontal cortex; reflecting permanent injury. 2. DTI tractography of the corticospinal tracts displayed revealed diminution of the number of projectional and commissural fibers over time. 3. Blood flow measurements demonstrated hypoperfusion on the fifth exams followed by hyperperfusion on the final two studies. 4. MR spectroscopy demonstrated that glutamine was elevated during hyperammonemia with myoinositol reduction, reflecting osmotic buffering. CONCLUSION This particular multimodal magnetic resonance neuroimaging showed novel, temporally specific manifestations over the disease course in OTC deficiency. This prospective imaging study expands our understanding of the effect of hyperammonemia on the structure and biochemistry of the nervous system.
Collapse
Affiliation(s)
- Kuntal Sen
- Division of Neurogenetics and Developmental Pediatrics, Center for Neuroscience and Behavioral Medicine, Children's National Hospital, Washington, DC, USA
| | - Matthew T Whitehead
- Department of Radiology, Children's National Hospital, Washington, DC, USA.,George Washington University of Medicine and Health Sciences, Washington, DC, USA
| | - Andrea L Gropman
- Division of Neurogenetics and Developmental Pediatrics, Center for Neuroscience and Behavioral Medicine, Children's National Hospital, Washington, DC, USA.,George Washington University of Medicine and Health Sciences, Washington, DC, USA
| |
Collapse
|
8
|
Ducich N, Ah Mew N, Bedoyan JK. The E273del variant of uncertain significance of the ornithine transcarbamylase gene - a case for reclassification. Mol Genet Metab Rep 2020; 23:100598. [PMID: 32420033 PMCID: PMC7218070 DOI: 10.1016/j.ymgmr.2020.100598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/28/2020] [Indexed: 11/26/2022] Open
Affiliation(s)
- Nicole Ducich
- School of Medicine, Case Western Reserve University (CWRU), Cleveland, OH, USA
| | - Nicholas Ah Mew
- Children's National Rare Disease Institute, The George Washington University, Washington, DC, USA
| | - Jirair K Bedoyan
- Department of Genetics and Genome Sciences, CWRU, Cleveland, OH, USA.,Department of Pediatrics, CWRU, Cleveland, OH, USA.,Center for Human Genetics, University Hospitals Cleveland Medical Center (UHCMC), Cleveland, OH, USA.,Center for Inherited Disorders of Energy Metabolism, UHCMC, Cleveland, OH, USA
| |
Collapse
|
9
|
Anderson A, Gropman A, Le Mons C, Stratakis C, Gandjbakhche A. Evaluation of neurocognitive function of prefrontal cortex in ornithine transcarbamylase deficiency. Mol Genet Metab 2020; 129:207-212. [PMID: 31952925 PMCID: PMC7416502 DOI: 10.1016/j.ymgme.2019.12.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/30/2019] [Accepted: 12/30/2019] [Indexed: 02/02/2023]
Abstract
Hyperammonia due to ornithine transcarbamylase deficiency (OTCD) can cause a range of deficiencies in domains of executive function and working memory. Only a few fMRI studies have focused on neuroimaging data in a population with OTCD. Yet, there is a need for monitoring the disease progression and neurocognitive function in this population. In this study, we used a non-invasive neuroimaging technique, functional Near Infrared Spectroscopy (fNIRS), to examine the hemodynamics of prefrontal cortex (PFC) based on neural activation in an OTCD population. Using fNIRS, we measured the activation in PFC of the participants while performing the Stroop task. Behavioral assessment such as reaction time and correct response were recorded. We investigated the difference in behavioral measures as well as brain activation in left and right PFC in patients with OTCD and controls. Results revealed a distinction in left PFC activation between controls and patients with OTCD, where control subjects showed higher task related activation increase. Subjects with OTCD also exhibited bilateral increase in PFC activation. There was no significant difference in response time or correct response between the two groups. Our findings suggest the alterations in neurocognitive function of PFC in OTCD compared to the controls despite the behavioral profiles exhibiting no such differences. This is a first study using fNIRS to examine a neurocognitive function in OTCD population and can provide a novel insight into the screening of OTCD progression and examining neurocognitive changes.
Collapse
Affiliation(s)
- Afrouz Anderson
- NIH, National Institute of Child Health and Human Development, Bethesda, MD 20892, United States of America
| | - Andrea Gropman
- Children's National Medical Center, Division of Neurogenetics and Neurodevelopmental Pediatrics, Washington, DC 20010, United States of America
| | - Cynthia Le Mons
- National Urea Cycle Disorders Foundation, Pasadena, California 91105
| | - Constantine Stratakis
- NIH, National Institute of Child Health and Human Development, Bethesda, MD 20892, United States of America
| | - Amir Gandjbakhche
- NIH, National Institute of Child Health and Human Development, Bethesda, MD 20892, United States of America.
| |
Collapse
|
10
|
Gropman AL, Anderson A. Novel imaging technologies for genetic diagnoses in the inborn errors of metabolism. JOURNAL OF TRANSLATIONAL GENETICS AND GENOMICS 2020; 4:429-445. [PMID: 35529470 PMCID: PMC9075742 DOI: 10.20517/jtgg.2020.09] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Many inborn errors of metabolism and genetic disorders affect the brain. The brain biochemistry may differ from that in the periphery and is not accessible by simple blood and urine sampling. Therefore, neuroimaging has proven to be a valuable tool to not only evaluate the brain structure, but also biochemistry, blood flow and function. Neuroimaging in patients with inborn errors of metabolism can include additional sequences in addition to T1 and T2-weighted imaging because in early stages, there may be no significant findings on the routine sequnces due to the lack of sensitivity or the evolution of abnormalities lags behind the ability of the imaging to detect it. In addition, findings on T1 and T2-weighted imaging of several inborn errors of metabolism may be non-specific and be seen in other non-genetic conditions. Therefore, additional neuroimaging modalities that have been employed including diffusion tensor imaging (DTI), magnetic resonance spectroscopy, functional MRI (fMRI), functional near infrared spectroscopy (fNIRS), or positron emission tomography (PET) imaging may further inform underlying changes in myelination, biochemistry, and functional connectivity. The use of Magnetic Resonance Spectroscopy in certain disorders may add a level of specificity depending upon the metabolite levels that are abnormal, as well as provide information about the process of brain injury (i.e., white matter, gray matter, energy deficiency, toxic buildup or depletion of key metabolites). It is even more challenging to understand how genetic or metabolic disorders contribute to short and/or long term changes in cognition which represent the downstream effects of IEMs. In order to image “cognition” or the downstream effects of a metabolic disorder on domains of brain function, more advanced techniques are required to analyze underlying fiber tracts or alternatively, methods such as fMRI enable generation of brain activation maps after both task based and resting state conditions. DTI can be used to look at changes in white matter tracks. Each imaging modality can explore an important aspect of the anatomy, physiology or biochemisty of the central nervous system. Their properties, pros and cons are discussed in this article. These imaging modalities will be discussed in the context of several inborn errors of metabolism including Galactosemia, Phenylketonruia, Maple syrup urine disease, Methylmalonic acidemia, Niemann-Pick Disease, type C1, Krabbe Disease, Ornithine transcarbamylase deficiency, Sjogren Larsson syndrome, Pelizeaus-Merzbacher disease, Pyruvate dehydrogenase deficiency, Nonketotic Hyperglycinemia and Fabry disease. Space constraints do not allow mention of all the disorders in which one of these modalities has been investigated, or where it would add value to diagnosis or disease progression.
Collapse
Affiliation(s)
- Andrea L Gropman
- Department of Neurology, Children's National Medical Center, Washington, DC 20010, USA
| | - Afrouz Anderson
- Department of Research, Focus Foundation, Crofton, MD 21035, USA
| |
Collapse
|
11
|
Häberle J, Burlina A, Chakrapani A, Dixon M, Karall D, Lindner M, Mandel H, Martinelli D, Pintos-Morell G, Santer R, Skouma A, Servais A, Tal G, Rubio V, Huemer M, Dionisi-Vici C. Suggested guidelines for the diagnosis and management of urea cycle disorders: First revision. J Inherit Metab Dis 2019; 42:1192-1230. [PMID: 30982989 DOI: 10.1002/jimd.12100] [Citation(s) in RCA: 249] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 04/04/2019] [Accepted: 04/08/2019] [Indexed: 02/06/2023]
Abstract
In 2012, we published guidelines summarizing and evaluating late 2011 evidence for diagnosis and therapy of urea cycle disorders (UCDs). With 1:35 000 estimated incidence, UCDs cause hyperammonemia of neonatal (~50%) or late onset that can lead to intellectual disability or death, even while effective therapies do exist. In the 7 years that have elapsed since the first guideline was published, abundant novel information has accumulated, experience on newborn screening for some UCDs has widened, a novel hyperammonemia-causing genetic disorder has been reported, glycerol phenylbutyrate has been introduced as a treatment, and novel promising therapeutic avenues (including gene therapy) have been opened. Several factors including the impact of the first edition of these guidelines (frequently read and quoted) may have increased awareness among health professionals and patient families. However, under-recognition and delayed diagnosis of UCDs still appear widespread. It was therefore necessary to revise the original guidelines to ensure an up-to-date frame of reference for professionals and patients as well as for awareness campaigns. This was accomplished by keeping the original spirit of providing a trans-European consensus based on robust evidence (scored with GRADE methodology), involving professionals on UCDs from nine countries in preparing this consensus. We believe this revised guideline, which has been reviewed by several societies that are involved in the management of UCDs, will have a positive impact on the outcomes of patients by establishing common standards, and spreading and harmonizing good practices. It may also promote the identification of knowledge voids to be filled by future research.
Collapse
Affiliation(s)
- Johannes Häberle
- University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
| | - Alberto Burlina
- Division of Inborn Metabolic Disease, Department of Pediatrics, University Hospital Padua, Padova, Italy
| | - Anupam Chakrapani
- Department of Metabolic Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Marjorie Dixon
- Dietetics, Great Ormond Street Hospital for Children, NHS Trust, London, UK
| | - Daniela Karall
- Clinic for Pediatrics, Division of Inherited Metabolic Disorders, Medical University of Innsbruck, Innsbruck, Austria
| | - Martin Lindner
- University Children's Hospital, Frankfurt am Main, Germany
| | - Hanna Mandel
- Institute of Human Genetics and metabolic disorders, Western Galilee Medical Center, Nahariya, Israel
| | - Diego Martinelli
- Division of Metabolism, Bambino Gesù Children's Hospital, Rome, Italy
| | - Guillem Pintos-Morell
- Centre for Rare Diseases, University Hospital Vall d'Hebron, Barcelona, Spain
- CIBERER_GCV08, Research Institute IGTP, Barcelona, Spain
- Universitat Autònoma de Barcelona, Barcelona, Spain
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anastasia Skouma
- Institute of Child Health, Agia Sofia Children's Hospital, Athens, Greece
| | - Aude Servais
- Service de Néphrologie et maladies métaboliques adulte Hôpital Necker 149, Paris, France
| | - Galit Tal
- The Ruth Rappaport Children's Hospital, Rambam Medical Center, Haifa, Israel
| | - Vicente Rubio
- Instituto de Biomedicina de Valencia (IBV-CSIC), Centro de Investigación Biomédica en Red para Enfermedades Raras (CIBERER), Valencia, Spain
| | - Martina Huemer
- University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
- Department of Paediatrics, Landeskrankenhaus Bregenz, Bregenz, Austria
| | | |
Collapse
|
12
|
Yaple ZA, Stevens WD, Arsalidou M. Meta-analyses of the n-back working memory task: fMRI evidence of age-related changes in prefrontal cortex involvement across the adult lifespan. Neuroimage 2019; 196:16-31. [DOI: 10.1016/j.neuroimage.2019.03.074] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 03/20/2019] [Accepted: 03/30/2019] [Indexed: 10/27/2022] Open
|
13
|
Wang H, He W, Wu J, Zhang J, Jin Z, Li L. A coordinate-based meta-analysis of the n-back working memory paradigm using activation likelihood estimation. Brain Cogn 2019; 132:1-12. [DOI: 10.1016/j.bandc.2019.01.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 01/20/2019] [Accepted: 01/21/2019] [Indexed: 11/29/2022]
|
14
|
Bernstein HG, Dobrowolny H, Keilhoff G, Steiner J. In human brain ornithine transcarbamylase (OTC) immunoreactivity is strongly expressed in a small number of nitrergic neurons. Metab Brain Dis 2017; 32:2143-2147. [PMID: 28868581 DOI: 10.1007/s11011-017-0105-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/29/2017] [Indexed: 12/15/2022]
Abstract
There is recent evidence for ornithine transcarbamylase (OTC) expression in adult human brain. We decided to immunocytochemically map OTC throughout brain, and to further characterize OTC-immunopositive neurons. By using double immunolabeling technique for OTC and neuronal nitric oxide synthase (nNOS) OTC protein expression was revealed in a small subset of nitrergic (nNOS) neurons. Since citrulline (the reaction product of OTC) enhances the bioavailability of L-arginine, the substrate of nNOS, it is conceivable that OTC activity supports NO production in nitrergic neurons.
Collapse
Affiliation(s)
- Hans-Gert Bernstein
- Department of Psychiatry and Psychotherapy, University of Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany.
| | - Hendrik Dobrowolny
- Department of Psychiatry and Psychotherapy, University of Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany
| | - Gerburg Keilhoff
- Institute of Biochemistry and Cell Biology, Medical Faculty, University of Magdeburg, D-39120, Magdeburg, Germany
| | - Johann Steiner
- Department of Psychiatry and Psychotherapy, University of Magdeburg, Leipziger Str. 44, D-39120, Magdeburg, Germany
| |
Collapse
|
15
|
Jiang Y, Almannai M, Sutton VR, Sun Q, Elsea SH. Quantitation of phenylbutyrate metabolites by UPLC-MS/MS demonstrates inverse correlation of phenylacetate:phenylacetylglutamine ratio with plasma glutamine levels. Mol Genet Metab 2017; 122:39-45. [PMID: 28888854 DOI: 10.1016/j.ymgme.2017.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/27/2017] [Accepted: 08/27/2017] [Indexed: 12/31/2022]
Abstract
Urea cycle disorders (UCDs) are genetic conditions characterized by nitrogen accumulation in the form of ammonia and caused by defects in the enzymes required to convert ammonia to urea for excretion. UCDs include a spectrum of enzyme deficiencies, namely n-acetylglutamate synthase deficiency (NAGS), carbamoyl phosphate synthetase I deficiency (CPS1), ornithine transcarbamylase deficiency (OTC), argininosuccinate lyase deficiency (ASL), citrullinemia type I (ASS1), and argininemia (ARG). Currently, sodium phenylbutyrate and glycerol phenylbutyrate are primary medications used to treat patients with UCDs, and long-term monitoring of these compounds is critical for preventing drug toxic levels. Therefore, a fast and simple ultra-performance liquid chromatography (UPLC-MS/MS) method was developed and validated for quantification of phenylbutyrate (PB), phenylacetate (PA), and phenylacetylglutamine (PAG) in plasma and urine. The separation of all three analytes was achieved in 2min, and the limits of detection were <0.04μg/ml. Intra-precision and inter-precision were <8.5% and 4% at two quality control concentrations, respectively. Average recoveries for all compounds ranged from 100% to 106%. With the developed assay, a strong correlation between PA and the PA/PAG ratio and an inverse correlation between PA/PAG ratio and plasma glutamine were observed in 35 patients with confirmed UCDs. Moreover, all individuals with a ratio ≥0.6 had plasma glutamine levels<1000μmol/l. Our data suggest that a PA/PAG ratio in the range of 0.6-1.5 will result in a plasma glutamine level<1000μmol/l without reaching toxic levels of PA.
Collapse
Affiliation(s)
- Yi Jiang
- Division of Biochemical Genetics, Baylor Genetics Laboratories, Houston, TX, United States
| | - Mohammed Almannai
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - V Reid Sutton
- Division of Biochemical Genetics, Baylor Genetics Laboratories, Houston, TX, United States; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Qin Sun
- Division of Biochemical Genetics, Baylor Genetics Laboratories, Houston, TX, United States; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Sarah H Elsea
- Division of Biochemical Genetics, Baylor Genetics Laboratories, Houston, TX, United States; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States.
| |
Collapse
|
16
|
Goldstein ED, Cannistraro R, Atwal PS, Meschia JF. Undiagnosed Partial Ornithine Transcarbamylase Deficiency Presenting Postoperatively as Agitated Delirium. Neurohospitalist 2017; 8:82-85. [PMID: 29623158 DOI: 10.1177/1941874417729983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Partial ornithine transcarbamylase deficiency (pOTCD), an enzymatic defect within the urea cycle, is an increasingly recognized etiology for hyperammonemia of unclear source following a stressor within female adults. Here we present a case of newly diagnosed pOTCD following a systemic stressor and prolonged hospitalization course. From a neurological perspective, prompt recognition provided the patient with a swift and near complete recovery. We briefly review the pertinent literature pertaining to this genetically based condition including historical context and current therapeutic approaches. Given the potential morbidity of prolonged hyperammonemia, neurohospitalists need to be aware of partial ornithine transcarbamylase as an entity.
Collapse
Affiliation(s)
- E D Goldstein
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
| | - R Cannistraro
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
| | - P S Atwal
- Department of Clinical Genomics Mayo Clinic, Jacksonville, FL, USA
| | - J F Meschia
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
| |
Collapse
|
17
|
Barkovich E, Robinson C, Gropman A. Brain biomarkers and neuroimaging to diagnose urea cycle disorders and assess prognosis. Expert Opin Orphan Drugs 2016. [DOI: 10.1080/21678707.2016.1242407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
18
|
Waisbren SE, Gropman AL, Batshaw ML. Improving long term outcomes in urea cycle disorders-report from the Urea Cycle Disorders Consortium. J Inherit Metab Dis 2016; 39:573-84. [PMID: 27215558 PMCID: PMC4921309 DOI: 10.1007/s10545-016-9942-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 12/31/2022]
Abstract
The Urea Cycle Disorders Consortium (UCDC) has conducted, beginning in 2006, a longitudinal study (LS) of eight enzyme deficiencies/transporter defects associated with the urea cycle. These include N-acetylglutamate synthase deficiency (NAGSD); Carbamyl phosphate synthetase 1 deficiency (CPS1D); Ornithine transcarbamylase deficiency (OTCD); Argininosuccinate synthetase deficiency (ASSD) (Citrullinemia); Argininosuccinate lyase deficiency (ASLD) (Argininosuccinic aciduria); Arginase deficiency (ARGD, Argininemia); Hyperornithinemia, hyperammonemia, homocitrullinuria (HHH) syndrome (or mitochondrial ornithine transporter 1 deficiency [ORNT1D]); and Citrullinemia type II (mitochondrial aspartate/glutamate carrier deficiency [CITRIN]). There were 678 UCD patients enrolled in 14 sites in the U.S., Canada, and Europe at the writing of this paper. This review summarizes findings of the consortium related to outcome, focusing primarily on neuroimaging findings and neurocognitive function. Neuroimaging studies in late onset OTCD offered evidence that brain injury caused by biochemical dysregulation may impact functional neuroanatomy serving working memory processes, an important component of executive function and regulation. Additionally, there were alteration in white mater microstructure and functional connectivity at rest. Intellectual deficits in OTCD and other urea cycle disorders (UCD) vary. However, when neuropsychological deficits occur, they tend to be more prominent in motor/performance areas on both intelligence tests and other measures. In some disorders, adults performed significantly less well than younger patients. Further longitudinal follow-up will reveal whether this is due to declines throughout life or to improvements in diagnostics (especially newborn screening) and treatments in the younger generation of patients.
Collapse
Affiliation(s)
- Susan E Waisbren
- Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Andrea L Gropman
- Children's Research Institute, Children's National Health System, Washington, DC, USA
| | - Mark L Batshaw
- Departments of Pediatrics and Neurology, George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
| |
Collapse
|
19
|
Pacheco-Colón I, Washington SD, Sprouse C, Helman G, Gropman AL, VanMeter JW. Reduced Functional Connectivity of Default Mode and Set-Maintenance Networks in Ornithine Transcarbamylase Deficiency. PLoS One 2015; 10:e0129595. [PMID: 26067829 PMCID: PMC4466251 DOI: 10.1371/journal.pone.0129595] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 05/11/2015] [Indexed: 12/21/2022] Open
Abstract
Background and Purpose Ornithine transcarbamylase deficiency (OTCD) is an X-chromosome linked urea cycle disorder (UCD) that causes hyperammonemic episodes leading to white matter injury and impairments in executive functioning, working memory, and motor planning. This study aims to investigate differences in functional connectivity of two resting-state networks—default mode and set-maintenance—between OTCD patients and healthy controls. Methods Sixteen patients with partial OTCD and twenty-two control participants underwent a resting-state scan using 3T fMRI. Combining independent component analysis (ICA) and region-of-interest (ROI) analyses, we identified the nodes that comprised each network in each group, and assessed internodal connectivity. Results Group comparisons revealed reduced functional connectivity in the default mode network (DMN) of OTCD patients, particularly between the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) node and bilateral inferior parietal lobule (IPL), as well as between the ACC/mPFC node and the posterior cingulate cortex (PCC) node. Patients also showed reduced connectivity in the set-maintenance network, especially between right anterior insula/frontal operculum (aI/fO) node and bilateral superior frontal gyrus (SFG), as well as between the right aI/fO and ACC and between the ACC and right SFG. Conclusion Internodal functional connectivity in the DMN and set-maintenance network is reduced in patients with partial OTCD compared to controls, most likely due to hyperammonemia-related white matter damage. Because several of the affected areas are involved in executive functioning, it is postulated that this reduced connectivity is an underlying cause of the deficits OTCD patients display in this cognitive domain.
Collapse
Affiliation(s)
- Ileana Pacheco-Colón
- Center for Functional and Molecular Imaging, Georgetown University, Washington, DC, United States of America
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States of America
- * E-mail:
| | - Stuart D. Washington
- Center for Functional and Molecular Imaging, Georgetown University, Washington, DC, United States of America
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Courtney Sprouse
- Department of Neurogenetics, Children’s National Health System, Washington, DC, United States of America
- George Washington University of the Health Sciences, Washington, DC, United States of America
| | - Guy Helman
- Department of Neurogenetics, Children’s National Health System, Washington, DC, United States of America
| | - Andrea L. Gropman
- Center for Functional and Molecular Imaging, Georgetown University, Washington, DC, United States of America
- Department of Neurogenetics, Children’s National Health System, Washington, DC, United States of America
- George Washington University of the Health Sciences, Washington, DC, United States of America
- Medical Genetics Branch, NHGRI, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John W. VanMeter
- Center for Functional and Molecular Imaging, Georgetown University, Washington, DC, United States of America
- Department of Neurology, Georgetown University Medical Center, Washington, DC, United States of America
| |
Collapse
|
20
|
Pacheco-Colón I, Fricke S, VanMeter J, Gropman AL. Advances in urea cycle neuroimaging: Proceedings from the 4th International Symposium on urea cycle disorders, Barcelona, Spain, September 2013. Mol Genet Metab 2014; 113:118-26. [PMID: 25066103 PMCID: PMC4177962 DOI: 10.1016/j.ymgme.2014.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 05/10/2014] [Indexed: 11/20/2022]
Abstract
Our previous imaging research performed as part of a Urea Cycle Rare Disorders Consortium (UCRDC) grant, has identified specific biomarkers of neurologic injury in ornithine transcarbamylase deficiency, OTCD. While characterization of mutations can be achieved in most cases, this information does not necessarily predict the severity of the underlying neurological syndrome. The biochemical consequences of any mutation may be modified additionally by a large number of factors, including contributions of other enzymes and transport systems that mediate flux through the urea cycle, diet and other environmental factors. These factors likely vary from one patient to another, and they give rise to heterogeneity of clinical severity. Affected cognitive domains include non-verbal learning, fine motor processing, reaction time, visual memory, attention, and executive function. Deficits in these capacities may be seen in symptomatic patients, as well as asymptomatic carriers with normal IQ and correlate with variances in brain structure and function in these patients. Using neuroimaging we can identify biomarkers that reflect the downstream impact of UCDs on cognition. This manuscript is a summary of the presentation from the 4th International Consortium on urea cycle disorders held in, Barcelona, Spain, September 2, 2014.
Collapse
Affiliation(s)
| | - Stanley Fricke
- Children's National Medical, USA; George Washington University, USA
| | - John VanMeter
- Center for Functional and Molecular Imaging, Georgetown University, USA
| | - Andrea L Gropman
- Center for Functional and Molecular Imaging, Georgetown University, USA; Children's National Medical, USA; George Washington University, USA.
| |
Collapse
|
21
|
Sprouse C, King J, Helman G, Pacheco-Colón I, Shattuck K, Breeden A, Seltzer R, VanMeter JW, Gropman AL. Investigating neurological deficits in carriers and affected patients with ornithine transcarbamylase deficiency. Mol Genet Metab 2014; 113:136-41. [PMID: 24881970 PMCID: PMC4458385 DOI: 10.1016/j.ymgme.2014.05.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/12/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Urea cycle disorders are caused by dysfunction in any of the six enzymes and two transport proteins involved in urea biosynthesis. Our study focuses on ornithine transcarbamylase deficiency (OTCD), an X-linked disorder that results in a dysfunctional mitochondrial enzyme, which prevents the synthesis of citrulline from carbamoyl phosphate and ornithine. This enzyme deficiency can lead to hyperammonemic episodes and severe cerebral edema. The objective of this study was to use a cognitive battery to expose the cognitive deficits in asymptomatic carriers of OTCD. MATERIALS AND METHODS In total, 81 participants were recruited as part of a larger urea cycle disorder imaging consortium study. There were 25 symptomatic participants (18 female, 7 male, 25.6 year s ± 12.72 years), 20 asymptomatic participants (20 female, 0 male, 37.6 years ± 15.19 years), and 36 healthy control participants (21 female, 15 male, 29.8 years ± 13.39 years). All participants gave informed consent to participate and were then given neurocognitive batteries with standard scores and T scores recorded. RESULTS When stratified by symptomatic participant, asymptomatic carrier, and control, the results showed significant differences in measures of executive function (e.g. CTMT and Stroop) and motor ability (Purdue Assembly) between all groups tested. Simple attention, academic measures, language and non-verbal motor abilities showed no significant differences between asymptomatic carriers and control participants, however, there were significant differences between symptomatic and control participant performance in these measures. CONCLUSIONS In our study, asymptomatic carriers of OTCD showed no significant differences in cognitive function compared to control participants until they were cognitively challenged with fine motor tasks, measures of executive function, and measures of cognitive flexibility. This suggests that cognitive dysfunction is best measurable in asymptomatic carriers after they are cognitively challenged.
Collapse
Affiliation(s)
- Courtney Sprouse
- Department of Neurogenetics, Children's National Medical Center, Washington D.C., USA; Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA
| | - Jessica King
- Department of Neurogenetics, Children's National Medical Center, Washington D.C., USA
| | - Guy Helman
- Department of Neurogenetics, Children's National Medical Center, Washington D.C., USA
| | - Ileana Pacheco-Colón
- Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA
| | - Kyle Shattuck
- Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA
| | - Andrew Breeden
- Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA
| | - Rebecca Seltzer
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - John W VanMeter
- Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA
| | - Andrea L Gropman
- Department of Neurogenetics, Children's National Medical Center, Washington D.C., USA; Center for Functional and Molecular Imaging, Georgetown University, Washington D.C., USA; George Washington University of Health Sciences, Washington D.C., USA
| |
Collapse
|
22
|
Gropman AL, Prust M, Breeden A, Fricke S, VanMeter J. Urea cycle defects and hyperammonemia: effects on functional imaging. Metab Brain Dis 2013; 28:269-75. [PMID: 23149878 PMCID: PMC3594356 DOI: 10.1007/s11011-012-9348-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 10/21/2012] [Indexed: 11/25/2022]
Abstract
The urea-cycle disorders (UCDs) are a group of congenital enzyme and carrier deficiencies predisposing to hyperammonemia (HA). HA causes changes in the central nervous system (CNS) including alterations of neurotransmitter function, cell volume, and energy deprivation ultimately leading to cerebral edema. Neuropathological findings of UCDs primarily reflect changes in astrocyte morphology. Neurological features accompanying acute HA include changes in behavior and consciousness in the short term, and potential for impairments in memory and executive function as long-term effects. Plasma measures of ammonia and glutamine, although useful for clinical monitoring, prove poor markers of CNS function. Multimodal neuroimaging has potential to investigate impact on cognitive function by interrogating neural networks, connectivity and biochemistry. As neuroimaging methods become increasingly sophisticated, they will play a critical role in clinical monitoring and treatment of metabolic disease. We describe our findings in UCDs; with focus on Ornithine Transcarbamylase deficiency (OTCD) the only X linked UCD.
Collapse
Affiliation(s)
- Andrea L Gropman
- Department of Neurology, Children's National Medical Center, George Washington University of Health Sciences, 111 Michigan Avenue, NW, Washington, DC 20010, USA.
| | | | | | | | | |
Collapse
|