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mental retardation genetics

Kimberly P Keil, Sunjay Sethi, Machelle D Wilson, Jill L Silverman, Isaac N Pessah, Pamela J Lein
Dendritic morphology is a critical determinant of neuronal connectivity, and calcium signaling plays a predominant role in shaping dendrites. Altered dendritic morphology and genetic mutations in calcium signaling are both associated with neurodevelopmental disorders (NDDs). In this study we tested the hypothesis that dendritic arborization and NDD-relevant behavioral phenotypes are altered by human mutations that modulate calcium-dependent signaling pathways implicated in NDDs. The dendritic morphology of pyramidal neurons in CA1 hippocampus and somatosensory cortex was quantified in Golgi-stained brain sections from juvenile mice of both sexes expressing either a human gain-of-function mutation in ryanodine receptor 1 (T4826I-RYR1), a human CGG repeat expansion (170-200 CGG repeats) in the fragile X mental retardation gene 1 (FMR1 premutation), both mutations (double mutation; DM), or wildtype (WT) mice...
October 12, 2018: Genes, Brain, and Behavior
Kishin Koh, Yuta Ichinose, Hiroyuki Ishiura, Haitian Nan, Jun Mitsui, Junya Takahashi, Wakiro Sato, Yoshiaki Itoh, Kyoko Hoshino, Shoji Tsuji, Yoshihisa Takiyama
PLA2G6-associated neurodegeneration (PLAN) comprises heterogeneous neurodegenerative disorders, including infantile neuroaxonal dystrophy, neurodegeneration with brain iron accumulation 2B, and Parkinson disease 14 (PARK14). In addition, very recently, PLA2G6 mutations have been reported to represent a phenotype of hereditary spastic paraplegia (HSP). In this study, we screened 383 HSP families to clarify the frequency of PLA2G6 mutations in the Japan Spastic Paraplegia Research Consortium, and revealed the clinical characteristics of HSP with PLA2G6 mutations...
October 9, 2018: Journal of Human Genetics
Ayako Kashimada, Setsuko Hasegawa, Toshihiro Nomura, Hiroshi Shiraku, Kengo Moriyama, Tomonori Suzuki, Keisuke Nakajima, Tomoko Mizuno, Kohsuke Imai, Yuji Sugawara, Tomohiro Morio, Satoko Kumada, Masatoshi Takagi
OBJECTIVES: Defects in DNA damage responses or repair mechanisms cause numerous rare inherited diseases, referred to as "DNA-repair defects" or "DNA damage deficiency", characterized by neurodegeneration, immunodeficiency, and/or cancer predisposition. Early accurate diagnosis is important for informing appropriate clinical management; however, diagnosis is frequently challenging and can be delayed, due to phenotypic heterogeneity. Comprehensive genomic analysis could overcome this disadvantage...
October 6, 2018: Brain & Development
Sha Sha, Xinna Chen, Min Liu, Aiping Zhou, Yanan Sun, Cunrong Pang, Xu Zhang
OBJECTIVE: To explore the candidate disease causing gene for a case with floppy infant syndrome (FIS). METHODS: Single nucleotide polymorphism array (SNP array) was used for analyzing the whole genome copy number mutations in the proband. Multiple PCR combined with denaturing high performance liquid chromatography (DHPLC) was employed to verify the suspected mutations in the proband and his family members. RESULTS: A large duplication arr [hg19] Xq13...
October 10, 2018: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
Ron Hochstenbach, Ellen van Binsbergen, Heleen Schuring-Blom, Arjan Buijs, Hans Kristian Ploos van Amstel
Whole genome sequencing (WGS) holds the potential to identify pathogenic gene mutations, copy number variation, uniparental disomy and structural rearrangements in a single genetic test. With its high diagnostic yield and decreasing costs, the question arises whether WGS can serve as a single test for all referrals to diagnostic genome laboratories ("one test fits all"). Here, we provide an estimate for the proportion of clinically relevant aberrations identified by light microscopy in postnatal referrals that would go undetected by WGS...
September 21, 2018: European Journal of Medical Genetics
Hildegard Nikki Hall, Kathleen A Williamson, David R FitzPatrick
Absence of part or all of the iris, aniridia, is a feature of several genetically distinct conditions. This review focuses on iris development and then the clinical features and molecular genetics of these iris malformations. Classical aniridia, a panocular eye malformation including foveal hypoplasia, is the archetypal phenotype associated with heterozygous PAX6 loss-of-function mutations. Since this was identified in 1991, many genetic mechanisms of PAX6 inactivation have been elucidated, the commonest alleles being intragenic mutations causing premature stop codons, followed by those causing C-terminal extensions...
September 22, 2018: Human Genetics
Yun-Shu Ouyang, Yi-Xiu Zhang, Hua Meng, Xi-Ning Wu, Qing-Wei Qi
Fetal adducted thumbs have been described in association with hydrocephalus and other abnormalities, but in cases without other structural malformations the determination of prognosis and recurrence risk is challenging. The aim of our study is to analyze the characteristics, natural history, and postnatal outcome of such cases.A retrospective study was conducted over a period of 4 years in a tertiary referral center. All fetuses diagnosed as adducted thumbs without other structural malformations comprised the study group...
September 2018: Medicine (Baltimore)
Inusha Panigrahi, Puneet Jain, Siyaram Didel, Sarita Agarwal, Srinivasan Muthuswamy, Ansuman Saha, Vinay Kulkarni
Background: A retrospective analysis using chromosomal microarray in syndromic patients with intellectual disability from genetic clinics of a tertiary healthcare center in India was conducted. Aim: To identify the spectrum of chromosomal abnormalities detected on microarray analysis. Settings and Design: Cases were identified among those with intellectual disability with dysmorphism attending genetic clinics of a tertiary care center. Patients and Methods: All patients attending genetic clinics over a 3-year period were analyzed...
September 2018: Neurology India
Maham Rais, Devin K Binder, Khaleel A Razak, Iryna M Ethell
Fragile X syndrome (FXS) is a neurodevelopmental disorder that causes intellectual disability. It is a leading known genetic cause of autism. In addition to cognitive, social, and communication deficits, humans with FXS demonstrate abnormal sensory processing including sensory hypersensitivity. Sensory hypersensitivity commonly manifests as auditory, tactile, or visual defensiveness or avoidance. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity, impaired habituation to repeated sounds, and reduced auditory attention in humans with FXS...
January 2018: ASN Neuro
Stephanie M Matheson, Grant A Walling, Sandra A Edwards
BACKGROUND: In polytocous livestock species, litter size and offspring weight act antagonistically; in modern pig breeds, selection for increased litter size has resulted in lower mean birth weights, an increased number of small piglets and an increased number of those affected by varying degrees of intrauterine growth retardation (IUGR). IUGR poses life-long challenges, both mental, with morphological brain changes and altered cognition, and physical, such as immaturity of organs, reduced colostrum intake and weight gain...
September 18, 2018: Genetics, Selection, Evolution: GSE
Ramireddy Sriroopreddy, Rakshanda Sajeed, Raghuraman P, Sudandiradoss C
Down syndrome, a genetic disorder of known attribution reveals several types of brain abnormalities resulting in mental retardation, inadequacy in speech and memory. In this study, we have presented a consolidative network approach to comprehend the intricacy of the associated genes of Down syndrome. In this analysis, the differentially expressed genes (DEG's) were identified and the central networks were constructed as upregulated and downregulated. Subsequently, GNB5, CDC42, SPTAN1, GNG2, GNAZ, PRKACB, SST, CD44, FGF2, PHLPP1, APP, and FYN were identified as the candidate hub genes by using topological parameters...
September 12, 2018: International Journal of Biological Macromolecules
Jie Chen, Xiao Lin, Kyoung Jin Park, Kang Ro Lee, Hyun-Ju Park
The protein lysine methyltransferase G9a, which controls gene expression by epigenetic regulation of H3K9 methylation, is related to various human diseases, including cancer, drug addiction, and mental retardation. In recent years, genetic, biological, and physiological evidence has established G9a inhibitors as potential chemotherapeutic agents for cancer treatment. In this study, we identified protoberberine alkaloid pseudodehydrocorydaline (CT13) as a novel G9a inhibitor, by structure-based virtual screening of in-house library containing natural product compounds...
September 2018: Journal of Computer-aided Molecular Design
Francisco Carratala-Marco, Patricia Andreo-Lillo, Marta Martinez-Morga, Teresa Escamez-Martínez, Arancha Botella-López, Carlos Bueno, Salvador Martinez
The engrailed homeobox protein (EN) plays an important role in the regionalization of the neural tube. EN distribution regulates the cerebellum and midbrain morphogenesis, as well as retinotectal synaptogenesis. In humans, the EN1 and EN2 genes code for the EN family of transcription factors. Genetic alterations in the expression of EN2 have been related to different neurologic conditions and more particularly to autism spectrum disorders (ASD). We aimed to study and compare the phenotypes of three series of patients: (1) patients with encephalic structural anomalies (ESA) and abnormalities in the genomic (DNA) and/or transcriptomic (RNAm) of EN2 (EN2-g), (2) ESA patients having other gene mutations (OG-g), and (3) ESA patients free of these mutations (NM-g)...
2018: Frontiers in Neuroanatomy
Xue Li, Xin Han, Xiaomeng Tu, Dan Zhu, Yue Feng, Tian Jiang, Youping Yang, Jia Qu, Jie-Guang Chen
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that has a strong genetic component. Disruptions of FOXP1, a transcription factor expressed in the developing cerebral cortex, were associated with ASD. FOXP1(R525X) is a de novo heterozygous mutation found in patients with autism and severe mental retardation. To explore the neuronal basis of FOXP1(R525X) in ASD, we created Foxp1(R521X), a mouse homolog of the human variant. Ectopic expression of Foxp1(R521X) led to cytoplasmic aggregates and activated macroautophagy in neuroblastoma N2a cells and the developing neuronal cells...
August 15, 2018: Cerebral Cortex
Zhi-Jie Gao, Qian Jiang, Qian Chen, Jing-Min Wang, Hong Pan
Supernumerary marker chromosome 15 is a rare chromosome abnormality. This paper reports the clinical diagnosis and treatment, as well as genetic defects, of a child with supernumerary marker chromosome 15. The patient was a 9.5-year-old girl who had mental and motor retardation since infancy, breast development at the age of 7 years, and seizures at the age of 8.5 years. Seizures occurred with various features and could not be controlled by a variety of antiepileptic drugs. No abnormalities were found by brain magnetic resonance imaging...
August 2018: Zhongguo Dang Dai Er Ke za Zhi, Chinese Journal of Contemporary Pediatrics
Uğur Berber, Mehmet Akif Özdemir, Ekrem Unal, Serpil Taheri, Serkan Yildiz, Keziban Korkmaz Bayramov, Yunus Güler, Hüseyin Per
Intracranial hemorrhage due to vitamin K deficiency is a serious disease that can lead to morbidity, mortality, and mental retardation. Our goal in this study is to determine the frequency of VKORC1-1639 G>A polymorphism in patients who have undergone intracranial hemorrhage due to vitamin K deficiency bleeding (VKDB). To study VKORC1-1639 G>A polymorphism, blood was drawn from patients (n = 51, age 8:0 ± 6:5 years) followed at the Pediatric Neurology and Hematology section, Faculty of Medicine, Erciyes University, between 1990 and 2016, diagnosed with VKDB as idiopathic or from patients diagnosed with intracranial hemorrhage due to secondary vitamin K deficiency and also from volunteers (n = 51, age 11 ± 4...
August 13, 2018: Clinical and Applied Thrombosis/hemostasis
Liyun Feng, Weiyi Cai, Jiusheng Jiang, Shaohua Sun, Chunli Jing, Lin Yuan
OBJECTIVE: To delineate the nature and origin of chromosomal copy number variants (CNVs) in a boy with mental retardation and multiple congenital malformation. METHODS: The karyotypes of the patient and his parents were analyzed with routine G-banded chromosomal analysis. Genome DNA was analyzed by next generation sequencing (NGS). RESULTS: The patient was found to harbor a structural aberration involving chromosome 3p. The karyotype of his father was 46,XY,t(3;7)(p26;q31), while his mother was found to be normal...
August 10, 2018: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
Jiaping Wang, Qingping Zhang, Xinhua Bao, Yan Chen, Shujie Yu
OBJECTIVE: To delineate the clinical and genetic characteristics of patients with Allan-Herndon-Dudley syndrome (AHDS). METHODS: Genetic testing was carried out by next generation sequencing on 117 patients featuring intellectual disability and developmental delay. Clinical information including clinical manifestation, brain magnetic resonance imaging(MRI), thyroid hormone levels, and electrocardiogram was collected for those with SLC16A2 mutations. RESULTS: Five male patients with SLC16A2 gene mutations were identified, including 2 affected brothers and 3 sporadic cases...
August 10, 2018: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
Pawan Kumar, Inusha Panigrahi, Naveen Sankhyan, Chirag Ahuja, Prasoon K Goyadi
Down syndrome (DS), resulting from trisomy 21, is a common cause of mental retardation. Around 20,000 babies with DS are born every year in India. There is an increased risk of cerebral infarction in children with DS, the common causes being thromboembolism secondary to atrioventricular canal defects, right-to-left shunting, myocardial dysmotility, or cardiac valvular abnormalities. Stroke due to other causes can also occur in patients with DS, and one of these is moyamoya disease. This can be diagnosed by magnetic resonance imaging and/or angiography in these patients...
April 2018: Journal of Pediatric Neurosciences
Aimé Lumaka, Valerie Race, Hilde Peeters, Anniek Corveleyn, Zeynep Coban-Akdemir, Shalini N Jhangiani, Xiaofei Song, Gerrye Mubungu, Jennifer Posey, James R Lupski, Joris R Vermeesch, Prosper Lukusa, Koenraad Devriendt
Pathogenic variants account for 4 to 41% of patients with intellectual disability (ID) or developmental delay (DD). In Sub-Saharan Africa, the prevalence of ID is thought to be higher, but data in Central Africa are limited to some case reports. In addition, clinical descriptions of some syndromes are not available for this population. This study aimed at providing an estimate for the fraction of ID/DD for which an underlying etiological genetic cause may be elucidated and provide insights into their clinical presentation in special institutions in a Central African country...
August 8, 2018: American Journal of Medical Genetics. Part A
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