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Freitag CM, Chiocchetti AG, Haslinger D, Yousaf A, Waltes R. [Genetic risk factors and their influence on neural development in autism spectrum disorders]. ZEITSCHRIFT FUR KINDER-UND JUGENDPSYCHIATRIE UND PSYCHOTHERAPIE 2021; 50:187-202. [PMID: 34128703 DOI: 10.1024/1422-4917/a000803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Genetic risk factors and their influence on neural development in autism spectrum disorders Abstract. Abstract. Autism spectrum disorders are etiologically based on genetic and specific gene x biologically relevant environmental risk factors. They are diagnosed based on behavioral characteristics, such as impaired social communication and stereotyped, repetitive behavior and sensory as well as special interests. The genetic background is heterogeneous, i. e., it comprises diverse genetic risk factors across the disorder and high interindividual differences of specific genetic risk factors. Nevertheless, risk factors converge regarding underlying biological mechanisms and shared pathways, which likely cause the autism-specific behavioral characteristics. The current selective literature review summarizes differential genetic risk factors and focuses particularly on mechanisms and pathways currently being discussed by international research. In conclusion, clinically relevant aspects and open translational research questions are presented.
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Affiliation(s)
- Christine M Freitag
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum Frankfurt, Goethe-Universität, Frankfurt am Main
| | - Andreas G Chiocchetti
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum Frankfurt, Goethe-Universität, Frankfurt am Main
| | - Denise Haslinger
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum Frankfurt, Goethe-Universität, Frankfurt am Main
| | - Afsheen Yousaf
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum Frankfurt, Goethe-Universität, Frankfurt am Main
| | - Regina Waltes
- Klinik für Psychiatrie, Psychosomatik und Psychotherapie des Kindes- und Jugendalters, Universitätsklinikum Frankfurt, Goethe-Universität, Frankfurt am Main
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Freitag CM, Haslinger D, Yousaf A, Waltes R. Clinical genetic testing and counselling in autism spectrum disorder. MED GENET-BERLIN 2020. [DOI: 10.1515/medgen-2020-2001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Autism spectrum disorders (ASDs) are phenotypically as well as genetically heterogeneous developmental disorders with a strong heritability. Clinical and basic science research has described many replicated genetic risk factors. Many findings can well be translated into clinical human genetic practice. The current article summarizes results of genetic studies in ASD, provides a diagnostic algorithm for the clinical human genetic work-up reflecting the German health care system options and gives information with regard to the obligatory genetic counselling after a clinical genetic assessment.
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Affiliation(s)
- Christine M. Freitag
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy , Autism Research and Intervention Center of Excellence , University Hospital Frankfurt, Goethe Universität , Deutschordenstr. 50 , Frankfurt am Main , Germany
| | - Denise Haslinger
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy , Autism Research and Intervention Center of Excellence , University Hospital Frankfurt, Goethe Universität , Deutschordenstr. 50 , Frankfurt am Main , Germany
| | - Afsheen Yousaf
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy , Autism Research and Intervention Center of Excellence , University Hospital Frankfurt, Goethe Universität , Deutschordenstr. 50 , Frankfurt am Main , Germany
| | - Regina Waltes
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy , Autism Research and Intervention Center of Excellence , University Hospital Frankfurt, Goethe Universität , Deutschordenstr. 50 , Frankfurt am Main , Germany
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Mao X, Li K, Tang B, Luo Y, Ding D, Zhao Y, Wang C, Zhou X, Liu Z, Zhang Y, Wang P, Xu Q, Sun Q, Xia K, Yan X, Jiang H, Lu S, Guo J. Novel mutations in ADSL for Adenylosuccinate Lyase Deficiency identified by the combination of Trio-WES and constantly updated guidelines. Sci Rep 2017; 7:1625. [PMID: 28487569 PMCID: PMC5431663 DOI: 10.1038/s41598-017-01637-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 03/31/2017] [Indexed: 01/09/2023] Open
Abstract
Whole-exome sequencing (WES), one of the next-generation sequencing (NGS), has become a powerful tool to identify exonic variants. Investigating causality of the sequence variants in human disease becomes an important part in NGS for the research and clinical applications. Recently, important guidelines on them have been published and will keep on updating. In our study, two Chinese families, with the clinical diagnosis of "Epilepsy", which presented with seizures, psychomotor retardation, hypotonia and etc. features, were sequenced by Trio-WES (including the proband and the unaffected parents), and a standard interpretation of the identified variants was performed referring to the recently updated guidelines. Finally, we identified three novel mutations (c.71 C > T, p.P24L; c.1387-1389delGAG, p.E463-; c.134 G > A, p.W45*; NM_000026) in ADSL in the two Chinese families, and confirmed them as the causal variants to the disease-Adenylosuccinate Lyase Deficiency. Previous reported specific therapy was also introduced to the patients after our refined molecular diagnosis, however, the effect was very limited success. In summary, our study demonstrated the power and advantages of WES in exploring the etiology of human disease. Using the constantly updated guidelines to conduct the WES study and to interpret the sequence variants are a necessary strategy to make the molecular diagnosis and to guide the individualized treatment of human disease.
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Affiliation(s)
- Xiao Mao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Kai Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Beisha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China
- National Clinical Research Center for Geriatric Medicine, Changsha, Hunan, P.R. China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China
- Parkinson's Disease Center of Beijing Institute for Brain Disorders, Beijing, P.R. China
- Collaborative Innovation Center for Brain Science, Shanghai, P.R. China
- Collaborative Innovation Center for Genetics and Development, Shanghai, P.R. China
| | - Yang Luo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Dongxue Ding
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Yuwen Zhao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Chunrong Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Xiaoting Zhou
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Zhenhua Liu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Yuan Zhang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Puzhi Wang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Qian Xu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Qiying Sun
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Kun Xia
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China
| | - Xinxiang Yan
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
| | - Hong Jiang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China
- National Clinical Research Center for Geriatric Medicine, Changsha, Hunan, P.R. China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China
| | - Shen Lu
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China
- National Clinical Research Center for Geriatric Medicine, Changsha, Hunan, P.R. China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China
| | - Jifeng Guo
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China.
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, P.R. China.
- National Clinical Research Center for Geriatric Medicine, Changsha, Hunan, P.R. China.
- Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, Hunan, P.R. China.
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Jurecka A, Zikanova M, Kmoch S, Tylki-Szymańska A. Adenylosuccinate lyase deficiency. J Inherit Metab Dis 2015; 38:231-42. [PMID: 25112391 PMCID: PMC4341013 DOI: 10.1007/s10545-014-9755-y] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 07/17/2014] [Accepted: 07/23/2014] [Indexed: 11/26/2022]
Abstract
Adenylosuccinate lyase ADSL) deficiency is a defect of purine metabolism affecting purinosome assembly and reducing metabolite fluxes through purine de novo synthesis and purine nucleotide recycling pathways. Biochemically this defect manifests by the presence in the biologic fluids of two dephosphorylated substrates of ADSL enzyme: succinylaminoimidazole carboxamide riboside (SAICAr) and succinyladenosine (S-Ado). More than 80 individuals with ADSL deficiency have been identified, but incidence of the disease remains unknown. The disorder shows a wide spectrum of symptoms from slowly to rapidly progressing forms. The fatal neonatal form has onset from birth and presents with fatal neonatal encephalopathy with a lack of spontaneous movement, respiratory failure, and intractable seizures resulting in early death within the first weeks of life. Patients with type I (severe form) present with a purely neurologic clinical picture characterized by severe psychomotor retardation, microcephaly, early onset of seizures, and autistic features. A more slowly progressing form has also been described (type II, moderate or mild form), as having later onset, usually within the first years of life, slight to moderate psychomotor retardation and transient contact disturbances. Diagnosis is facilitated by demonstration of SAICAr and S-Ado in extracellular fluids such as plasma, cerebrospinal fluid and/or followed by genomic and/or cDNA sequencing and characterization of mutant proteins. Over 50 ADSL mutations have been identified and their effects on protein biogenesis, structural stability and activity as well as on purinosome assembly were characterized. To date there is no specific and effective therapy for ADSL deficiency.
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Affiliation(s)
- Agnieszka Jurecka
- Department of Genetics, University of Gdańsk, ul. Wita Stwosza 59, 80-308, Gdańsk, Poland,
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Rosti RO, Sadek AA, Vaux KK, Gleeson JG. The genetic landscape of autism spectrum disorders. Dev Med Child Neurol 2014; 56:12-8. [PMID: 24116704 DOI: 10.1111/dmcn.12278] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/22/2013] [Indexed: 12/13/2022]
Abstract
Autism spectrum disorders (ASDs) are a group of heterogeneous neurodevelopmental disorders that show impaired communication and socialization, restricted interests, and stereotypical behavioral patterns. Recent advances in molecular medicine and high throughput screenings, such as array comparative genomic hybridization (CGH) and exome and whole genome sequencing, have revealed both novel insights and new questions about the nature of this spectrum of disorders. What has emerged is a better understanding about the genetic architecture of various genetic subtypes of ASD and correlations of genetic mutations with specific autism subtypes. Based on this new information, we outline a strategy for advancing diagnosis, prognosis, and counseling for patients and families.
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Affiliation(s)
- Rasim O Rosti
- Department of Neurosciences and Pediatrics, Howard Hughes Medical Institute, University of California, San Diego, CA, USA
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Ghaziuddin M, Al-Owain M. Autism spectrum disorders and inborn errors of metabolism: an update. Pediatr Neurol 2013; 49:232-6. [PMID: 23921282 DOI: 10.1016/j.pediatrneurol.2013.05.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/28/2013] [Accepted: 05/31/2013] [Indexed: 02/07/2023]
Abstract
BACKGROUND Autism spectrum disorder is characterized by social communicative deficits with restricted interests occurring in about 1% of the population. Although its exact cause is not known, several factors have been implicated in its etiology, including inborn errors of metabolism. Although relatively uncommon, these disorders frequently occur in countries with high rates of consanguinity and are often associated with behavioral problems, such as hyperactivity and aggression. The aim of this review is to examine the association of autism with these conditions. METHOD A computer-assisted search was performed to identify the most common inborn errors of metabolism associated with autism. RESULTS The following disorders were identified: phenylketonuria, glucose-6-phosphatase deficiency, propionic acidemia, adenosine deaminase deficiency, Smith-Lemli-Opitz syndrome and mitochondrial disorders, and the recently described branched chain ketoacid dehydrogenase kinase deficiency. CONCLUSION The risk of autistic features is increased in children with inborn errors of metabolism, especially in the presence of cognitive and behavioral deficits. We propose that affected children should be screened for autism.
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Affiliation(s)
- Mohammad Ghaziuddin
- University of Michigan, Ann Arbor, Michigan, and King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
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Jinnah HA, Sabina RL, Van Den Berghe G. Metabolic disorders of purine metabolism affecting the nervous system. HANDBOOK OF CLINICAL NEUROLOGY 2013; 113:1827-36. [PMID: 23622405 DOI: 10.1016/b978-0-444-59565-2.00052-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The purines are a group of molecules used by all cells for many vital biochemical processes including energy-requiring enzymatic reactions, cofactor-requiring reactions, synthesis of DNA or RNA, signaling pathways within and between cells, and other processes. Defects in some of the enzymes of purine metabolism are known to be associated with specific clinical disorders, and neurological problems may be a presenting sign or the predominant clinical problem for several of them. This chapter describes three disorders for which the clinical features and metabolic basis are well characterized. Deficiency of adenylosuccinate-lyase (ADSL) causes psychomotor retardation, epilepsy, and autistic features. Lesch-Nyhan disease is caused by deficiency of hypoxanthine-guanine phosphoribosyltransferase (HPRT) and is characterized by hyperuricemia, motor and cognitive disability, and self-injurious behavior. Deficiency of myoadenylate deaminase (mAMPD) is associated with myopathic features. In addition to these disorders, several other disorders are briefly summarized. These include defects of phosphoribosylpyrophosphate synthase, adenosine deaminase (ADA), purine nucleoside phosphorylase (PND), deoxyguanosine kinase (dGK), or IMP dehydrogenase (IMPDH). Each of these disorders provides an unusual window on the unique importance of purine metabolism for function of different parts of the nervous system.
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Affiliation(s)
- H A Jinnah
- Departments of Neurology and Human Genetics, Emory University School of Medicine, Atlanta, GA, USA.
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Jurecka A, Jurkiewicz E, Tylki-Szymanska A. Magnetic resonance imaging of the brain in adenylosuccinate lyase deficiency: a report of seven cases and a review of the literature. Eur J Pediatr 2012; 171:131-8. [PMID: 21625931 DOI: 10.1007/s00431-011-1503-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 05/17/2011] [Indexed: 11/27/2022]
Abstract
Adenylosuccinate lyase (ADSL) deficiency is a rare autosomal recessive disorder of purine metabolism. Patients may present with a wide range of neurological symptoms. Head imaging abnormalities have been reported only rarely in the scientific literature and include atrophy of the cerebral cortex, corpus callosum, cerebellar vermis, lack of myelination, delayed myelination, anomalies of the white matter, and lissencephaly. The pathogenesis of abnormalities remains unknown. To further the understanding of the spectrum of brain abnormalities associated with ADSL deficiency, we examined the magnetic resonance findings in seven Polish patients with different clinical phenotypes and genotypes. Head MRI showed impaired white matter myelination with various degrees of global supra- and infratentorial white matter loss including widening of the lateral ventricles, enlargement of the subarachnoid spaces, atrophy of the cerebrum, hypoplasia of the cerebellar hemispheres and enlargement of the cisterna magna, and white matter abnormal hyperintense signal on T(2)-weighted sequences. We recommend performing a detailed analysis of urine and plasma purine metabolites in patients who have neurological findings, including developmental delay, microcephaly, autistic features, neonatal encephalopathy, and seizures especially if MRI findings such as delayed or lack of myelination, white matter abnormal signal, and atrophy of the cerebrum and/or cerebellum are also present. Greater awareness of adenylosuccinate lyase deficiency among general pediatricians, neonatologists, pediatric neurologists, and also radiologists is the key to identifying the disorder at an early stage.
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Affiliation(s)
- Agnieszka Jurecka
- The Children's Memorial Health Institute, Al. Dzieci Polskich 20, Warsaw, Poland.
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Abstract
Autism is an etiologically and clinically heterogeneous group of disorders, diagnosed solely by the complex behavioral phenotype. On the basis of the high-heritability index, geneticists are confident that autism will be the first behavioral disorder for which the genetic basis can be well established. Although it was initially assumed that major genome-wide and candidate gene association studies would lead most directly to common autism genes, progress has been slow. Rather, most discoveries have come from studies of known genetic disorders associated with the behavioral phenotype. New technology, especially array chromosomal genomic hybridization, has both increased the identification of putative autism genes and raised to approximately 25%, the percentage of children for whom an autism-related genetic change can be identified. Incorporating clinical geneticists into the diagnostic and autism research arenas is vital to the field. Interpreting this new technology and deciphering autism's genetic montage require the skill set of the clinical geneticist including knowing how to acquire and interpret family pedigrees, how to analyze complex morphologic, neurologic, and medical phenotypes, sorting out heterogeneity, developing rational genetic models, and designing studies. The current emphasis on deciphering autism spectrum disorders has accelerated the field of neuroscience and demonstrated the necessity of multidisciplinary research that must include clinical geneticists both in the clinics and in the design and implementation of basic, clinical, and translational research.
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Jurecka A, Tylki-Szymanska A, Zikanova M, Krijt J, Kmoch S. D-ribose therapy in four Polish patients with adenylosuccinate lyase deficiency: absence of positive effect. J Inherit Metab Dis 2008; 31 Suppl 2:S329-32. [PMID: 18649008 DOI: 10.1007/s10545-008-0904-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 04/09/2008] [Accepted: 04/17/2008] [Indexed: 10/21/2022]
Abstract
Deficiency of adenylosuccinate lyase (ADSL) (OMIM 103050) is an autosomal recessive disorder of the purine de novo synthesis pathway and purine nucleotide cycle, diagnosed so far in approximately 50 patients. The clinical presentation is characterized by severe neurological involvement including hypotonia, seizures, developmental delay and autistic features. Epilepsy in ADSL deficiency is frequent and occurs in approximately two-thirds of patients, beginning either early in the neonatal period or after the first year of life. At present there is no treatment of proven clinical efficacy. Despite of the increasing number of ADSL-deficient patients reported, there are only a few communications of therapeutic considerations or efforts. Among them only two showed some beneficial effects in ADSL-deficient patients. D-ribose, a simple and relatively cheap therapy, has been associated with improvement of behaviour and progressive reduction of the seizure frequency in one 13-year-old patient with ADSL deficiency. In this study we have re-examined D-ribose treatment in four ADSL-deficient patients. Assessments consisted of biochemical markers and neurological outcome. The 12-month trial of D-ribose failed to show any clinical benefit in ADSL patients with both milder and severe phenotype. D-ribose administration was accompanied by neither reduction in seizure frequency nor growth enhancement. Additionally, patients with milder type II presented the first seizure after 4 and 8 months of the D-ribose treatment. Therefore, we could not confirm a positive effect of D-ribose as previously reported.
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Affiliation(s)
- A Jurecka
- Department of Metabolic Diseases, Endocrinology and Diabetology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730, Warsaw, Poland.
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Hettinger JA, Liu X, Holden JJA. The G22A Polymorphism of the ADA Gene and Susceptibility to Autism Spectrum Disorders. J Autism Dev Disord 2007; 38:14-9. [PMID: 17340203 DOI: 10.1007/s10803-006-0354-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Accepted: 12/29/2006] [Indexed: 11/26/2022]
Abstract
Inborn errors of purine metabolism have been implicated as a cause for some cases of autism. This hypothesis is supported by the finding of decreased adenosine deaminase (ADA) activity in the sera of some children with autism and reports of an association of the A allele of the ADA G22A (Asp8Asn) polymorphism in individuals with autism of Italian-descent. We tested the ADA G22A polymorphism in 126 North American affected sib-pair families but found no aberrant allele distributions in cases versus controls. Instead, we found an increased transmission of the G allele from fathers to affected children. Our findings suggest that the ADA G22A polymorphism plays a minimal role in susceptibility to autism in North American families.
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Affiliation(s)
- Joe A Hettinger
- Department of Physiology, Queen's University, Kingston, ON, Canada
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Abstract
PURPOSE Clinical geneticists are often asked to evaluate patients with autism spectrum disorders (ASDs) in reference to questions about cause and recurrence risk. Recent advances in diagnostic testing technology have greatly increased the options available to them. It is not currently clear what the overall diagnostic yield of a battery of tests, either collectively or individually, might be. The purpose of this study was to evaluate the diagnostic yield of a stepwise approach we have implemented in our clinics. METHODS We used a three-tiered neurogenetic evaluation scheme designed to determine the cause of ASDs in patients referred for clinical genetic consultation. We reviewed the results of our diagnostic evaluations on all patients referred with a confirmed diagnosis of autism over a 3-year period. RESULTS By using this approach, we found an overall diagnostic yield for ASDs of more than 40%. This represents a significant increase in the diagnostic yield reported just a few years ago. CONCLUSIONS Given the implications of these diagnoses on recurrence risk and associated medical conditions, a targeted neurogenetic evaluation of all persons with ASDs seems warranted. We discuss the issues in the future implementation of a fourth tier to the evaluation with the potential for an even higher diagnostic yield.
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Affiliation(s)
- G Bradley Schaefer
- Munroe-Meyer Institute for Genetics and Rehabilitation, 985430 University of Nebraska Medical Center, Omaha, NE 68198, USA
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Cohen D, Pichard N, Tordjman S, Baumann C, Burglen L, Excoffier E, Lazar G, Mazet P, Pinquier C, Verloes A, Héron D. Specific Genetic Disorders and Autism: Clinical Contribution Towards their Identification. J Autism Dev Disord 2005; 35:103-16. [PMID: 15796126 DOI: 10.1007/s10803-004-1038-2] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Autism is a heterogeneous disorder that can reveal a specific genetic disease. This paper describes several genetic diseases consistently associated with autism (fragile X, tuberous sclerosis, Angelman syndrome, duplication of 15q11-q13, Down syndrome, San Filippo syndrome, MECP2 related disorders, phenylketonuria, Smith-Magenis syndrome, 22q13 deletion, adenylosuccinate lyase deficiency, Cohen syndrome, and Smith-Lemli-Opitz syndrome) and proposes a consensual and economic diagnostic strategy to help practitioners to identify them. A rigorous initial clinical screening is presented to avoid unnecessary laboratory and imaging studies. Regarding psychiatric nosography, the concept of "syndromal autism"--autism associated with other clinical signs should be promoted because it may help to distinguish patients who warrant a multidisciplinary approach and further investigation.
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Affiliation(s)
- David Cohen
- Service de Psychiatrie de l'Enfant et de l'Adolescent, Groupe Hospitalier Pitié-Salpétrière, Paris.
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Sivendran S, Patterson D, Spiegel E, McGown I, Cowley D, Colman RF. Two novel mutant human adenylosuccinate lyases (ASLs) associated with autism and characterization of the equivalent mutant Bacillus subtilis ASL. J Biol Chem 2004; 279:53789-97. [PMID: 15471876 DOI: 10.1074/jbc.m409974200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An Australian patient with autism was found to be heterozygous for two mutations in the gene encoding adenylosuccinate lyase (ASL), resulting in the protein mutations E80D and D87E. The patient's mother carried only the E80D mutation. The equivalent positions are 62 and 69 in Bacillus subtilis ASL. Although both human and B. subtilis enzymes normally have Asp at position 87 (or 69), the B. subtilis ASL has Ile and Asp at 62 and 65, respectively, whereas human ASL has Glu and Arg at the equivalent positions. We have constructed, expressed, and purified the double mutant I62E/D65R as a "humanized" normal B. subtilis enzyme to compare with enzymes with a single mutation at position 62 (I62D/D65R), at position 69 (I62E/D65R/D69E), or at both positions (I62D/D65R/D69E). V(max) for conversion of adenylosuccinate to AMP and fumarate is 0.57 micromol/min/mg for I62E/D65R, 0.064 micromol/min/mg for I62D/D65R, 0.27 micromol/min/mg for I62E/D65R/D69E, and 0.069 micromol/min/mg for I62D/D65R/D69E. The K(m) for adenylosuccinate is elevated in the X62D mutants, and I62D/D65R is the least stable of these ASLs at 37 degrees C. The CD spectra of mutant and wild type enzymes are similar; thus, there are no appreciable structural changes. Clearly the Asp(62) causes the most drastic effect on ASL function, whereas the Glu(69) mutation produces only modest change. These results emphasize the importance of expanding tests for ASL deficiency to individuals with developmental delay of any severity, including individuals with autistic spectrum disorder. This study further demonstrates the usefulness of the B. subtilis ASL as a model to mimic the defective enzyme in ASL deficiency.
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Affiliation(s)
- Sharmila Sivendran
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
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