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Gaceta Medica de Mexico 2020Fragile X syndrome is the monogenetic condition that produces more cases of autism and intellectual disability. The repetition of CGG triplets (> 200) and their... (Review)
Review
Fragile X syndrome is the monogenetic condition that produces more cases of autism and intellectual disability. The repetition of CGG triplets (> 200) and their methylation entail the silencing of the FMR1 gene. The FMRP protein (product of the FMR1 gene) interacts with ribosomes by controlling the translation of specific messengers, and its loss causes alterations in synaptic connectivity. Screening for fragile X syndrome is performed by polymerase chain reaction. Current recommendation of the American Academy of Pediatrics is to test individuals with intellectual disability, global developmental retardation or with a family history of presence of the mutation or premutation. Hispanic countries such as Colombia, Chile and Spain report high prevalence of fragile X syndrome and have created fragile X national associations or corporations that seek to bring patients closer to available diagnostic and treatment networks.
Topics: Attention Deficit Disorder with Hyperactivity; Autistic Disorder; Checklist; Child, Preschool; Female; Fragile X Mental Retardation Protein; Fragile X Syndrome; Gene Silencing; Genetic Testing; Humans; Intellectual Disability; Male; Mutation; Pedigree; Phenotype; Ribosomes; Sex Factors; Synaptic Transmission
PubMed: 32026885
DOI: 10.24875/GMM.19005275 -
Journal of Mother and Child Mar 2022Joubert syndrome (JS; MIM PS213300) is a rare genetic autosomal recessive disease characterized by cerebellar vermis hypoplasia, a distinctive malformation of the... (Review)
Review
Joubert syndrome (JS; MIM PS213300) is a rare genetic autosomal recessive disease characterized by cerebellar vermis hypoplasia, a distinctive malformation of the cerebellum and the so-called "molar tooth sign." Other characteristic features are hypotonia with lateral ataxia, intellectual disability/mental retardation, oculomotor apraxia, retinal dystrophy, abnormalities in the respiratory system, renal cysts, hepatic fibrosis, and skeletal changes. Such pleiotropic characteristics are typical of many disorders involving primary cilium aberrations, providing a significant overlap between JS and other ciliopathies such as nephronophthisis, Meckel syndrome, and Bardet-Biedl syndrome. This review will describe some characteristics of JS associated with changes in 35 genes, and will also address subtypes of JS, clinical diagnosis, and the future of therapeutic developments.
Topics: Humans; Cerebellum; Abnormalities, Multiple; Eye Abnormalities; Retina; Polycystic Kidney Diseases; Intellectual Disability
PubMed: 36803942
DOI: 10.34763/jmotherandchild.20222601.d-22-00034 -
Indian Journal of Pediatrics Feb 2023Intellectual disability (ID) is a common cause of referral to the pediatricians, geneticists, and pediatric neurologists. A thorough clinical evaluation and a stepwise... (Review)
Review
Intellectual disability (ID) is a common cause of referral to the pediatricians, geneticists, and pediatric neurologists. A thorough clinical evaluation and a stepwise investigative approach using a combination of traditional genetic techniques and appropriate latest genomic technologies can help in arriving at a diagnosis. In the current "omics" era, adopting a multiomics approach would further assist in solving the undiagnosed cases with intellectual disability.
Topics: Child; Humans; Intellectual Disability; Exome; Genomics; High-Throughput Nucleotide Sequencing
PubMed: 36441387
DOI: 10.1007/s12098-022-04345-3 -
Orphanet Journal of Rare Diseases May 2021Calcium ions are involved in several human cellular processes including corticogenesis, transcription, and synaptogenesis. Nevertheless, the relationship between calcium... (Review)
Review
BACKGROUND
Calcium ions are involved in several human cellular processes including corticogenesis, transcription, and synaptogenesis. Nevertheless, the relationship between calcium channelopathies (CCs) and intellectual disability (ID)/global developmental delay (GDD) has been poorly investigated. We hypothesised that CCs play a major role in the development of ID/GDD and that both gain- and loss-of-function variants of calcium channel genes can induce ID/GDD. As a result, we performed a systematic review to investigate the contribution of CCs, potential mechanisms underlying their involvement in ID/GDD, advancements in cell and animal models, treatments, brain anomalies in patients with CCs, and the existing gaps in the knowledge. We performed a systematic search in PubMed, Embase, ClinVar, OMIM, ClinGen, Gene Reviews, DECIPHER and LOVD databases to search for articles/records published before March 2021. The following search strategies were employed: ID and calcium channel, mental retardation and calcium channel, GDD and calcium channel, developmental delay and calcium channel.
MAIN BODY
A total of 59 reports describing 159 cases were found in PubMed, Embase, ClinVar, and LOVD databases. Variations in ten calcium channel genes including CACNA1A, CACNA1C, CACNA1I, CACNA1H, CACNA1D, CACNA2D1, CACNA2D2, CACNA1E, CACNA1F, and CACNA1G were found to be associated with ID/GDD. Most variants exhibited gain-of-function effect. Severe to profound ID/GDD was observed more for the cases with gain-of-function variants as compared to those with loss-of-function. CACNA1E, CACNA1G, CACNA1F, CACNA2D2 and CACNA1A associated with more severe phenotype. Furthermore, 157 copy number variations (CNVs) spanning calcium genes were identified in DECIPHER database. The leading genes included CACNA1C, CACNA1A, and CACNA1E. Overall, the underlying mechanisms included gain- and/ or loss-of-function, alteration in kinetics (activation, inactivation) and dominant-negative effects of truncated forms of alpha1 subunits. Forty of the identified cases featured cerebellar atrophy. We identified only a few cell and animal studies that focused on the mechanisms of ID/GDD in relation to CCs. There is a scarcity of studies on treatment options for ID/GDD both in vivo and in vitro.
CONCLUSION
Our results suggest that CCs play a major role in ID/GDD. While both gain- and loss-of-function variants are associated with ID/GDD, the mechanisms underlying their involvement need further scrutiny.
Topics: Calcium; Calcium Channels, L-Type; Channelopathies; Child; DNA Copy Number Variations; Developmental Disabilities; Humans; Intellectual Disability
PubMed: 33985586
DOI: 10.1186/s13023-021-01850-0 -
Psychiatric Services (Washington, D.C.) Mar 2022Individuals with intellectual and developmental disabilities (IDD) are at high risk of co-occurring mental health conditions, including major depressive disorder,... (Review)
Review
Individuals with intellectual and developmental disabilities (IDD) are at high risk of co-occurring mental health conditions, including major depressive disorder, bipolar disorder, anxiety disorders, psychotic illnesses, impulse control disorders, and others. Because of symptoms associated with these illnesses and with the disabilities themselves, these individuals are often served in a mental health service system framework. However, treatment for them in these settings has typically not been sufficiently nimble, knowledgeable, or adept. Most mental health professionals receive little training about the needs of this population, and system structures typically bifurcate care, when, in reality, conditions can be complex and overlapping. In this first of two articles on care for persons with IDD in the mental health system, the authors provide a clinical overview of these neurodevelopmental disorders and of mental health and other conditions that co-occur with IDD. Considerations and challenges for treating this population in the mental health system include early recognition of mental health conditions, which often requires caregiver and family input, as well as information from a variety of additional collateral sources; the importance of trauma-informed and person-centered care; the promotion of self-determination through use of decision supports; use of approaches such as applied behavior analysis to develop a frame to address challenging behaviors; and the need to properly assess and provide thoughtful pharmacologic intervention when appropriate. The ability of individuals with IDD to thrive in a wide range of community integration opportunities depends on many factors, and clinicians must understand and use the available approaches for treating them.
Topics: Child; Depressive Disorder, Major; Developmental Disabilities; Disabled Persons; Humans; Intellectual Disability; Mental Health
PubMed: 34346730
DOI: 10.1176/appi.ps.201900504 -
The Journal of Maternal-fetal &... Oct 2022Congenital hypothyroidism (CH) is the commonest preventable cause of mental retardation in human species. It is so important for clinician to know its etiology...
Congenital hypothyroidism (CH) is the commonest preventable cause of mental retardation in human species. It is so important for clinician to know its etiology epidemiology, clinical manifestation and treatment strategies. Since it is one of the rare serious diseases that should not be diagnosed clinically because late clinical features corresponds to advanced mental retardation, the neonatal screening detection is the best and preferable way of early diagnosis of this congenital disease. Confirmatory laboratory and radiological diagnostic tests should be performed immediately after the positive neonatal screening test. In order to prevent mental defects and to maintain long term clinical as well as biochemical euthyroidism in affected children its diagnosis approach, medical treatment and follow-up should be well established knowledge to all pediatricians during the childhood period and later on to general practitioners when these individuals grow up as adults. Congenital hypothyroidism is a potentially serious disease that we need to emphasize on early detection, using proper diagnostic tools and early and planned therapeutic approach.
Topics: Child; Congenital Hypothyroidism; Humans; Infant, Newborn; Intellectual Disability; Neonatal Screening
PubMed: 33115295
DOI: 10.1080/14767058.2020.1838480 -
Journal of the College of Physicians... Apr 2022Kleefstra syndrome (KS), previously referred to as 9q subtelomeric deletion syndrome (9qSTDS), is characterised by moderate to severe developmental delay/mental...
Kleefstra syndrome (KS), previously referred to as 9q subtelomeric deletion syndrome (9qSTDS), is characterised by moderate to severe developmental delay/mental retardation, childhood hypotonia, and brachy-microcephaly (main clinical phenotype), midface hypoplasia, prognathism, lip and eyebrow shape anomalies. The true prevalence of KS is unknown, but it is estimated that it occurs with a frequency of 1/200.000 in cases with mental retardation. On literature search, approximately 110 patients have been reported so far. Genetic analysis should be planned and interdisciplinary monitoring should be provided in cases suspected to have KS. Key Words: Child, Genetic disorder, Kleefstra Syndrome, Dysmorphism.
Topics: Child; Chromosome Deletion; Chromosomes, Human, Pair 9; Craniofacial Abnormalities; Heart Defects, Congenital; Humans; Intellectual Disability; Syndrome
PubMed: 35633020
DOI: 10.29271/jcpsp.2022.Supp1.S76 -
Colombia Medica (Cali, Colombia) 2023Fragile X syndrome is caused by the expansion of CGG triplets in the gene, which generates epigenetic changes that silence its expression. The absence of the protein... (Review)
Review
Fragile X syndrome is caused by the expansion of CGG triplets in the gene, which generates epigenetic changes that silence its expression. The absence of the protein coded by this gene, FMRP, causes cellular dysfunction, leading to impaired brain development and functional abnormalities. The physical and neurologic manifestations of the disease appear early in life and may suggest the diagnosis. However, it must be confirmed by molecular tests. It affects multiple areas of daily living and greatly burdens the affected individuals and their families. Fragile X syndrome is the most common monogenic cause of intellectual disability and autism spectrum disorder; the diagnosis should be suspected in every patient with neurodevelopmental delay. Early interventions could improve the functional prognosis of patients with Fragile X syndrome, significantly impacting their quality of life and daily functioning. Therefore, healthcare for children with Fragile X syndrome should include a multidisciplinary approach.
Topics: Humans; Child; Fragile X Syndrome; Autism Spectrum Disorder; Quality of Life; Intellectual Disability; Fragile X Mental Retardation Protein
PubMed: 37664646
DOI: 10.25100/cm.v54i2.5089 -
Nature Reviews. Neuroscience May 2021Fragile X syndrome (FXS) is the most common inherited form of intellectual disability and the leading monogenic cause of autism. The condition stems from loss of fragile... (Review)
Review
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability and the leading monogenic cause of autism. The condition stems from loss of fragile X mental retardation protein (FMRP), which regulates a wide range of ion channels via translational control, protein-protein interactions and second messenger pathways. Rapidly increasing evidence demonstrates that loss of FMRP leads to numerous ion channel dysfunctions (that is, channelopathies), which in turn contribute significantly to FXS pathophysiology. Consistent with this, pharmacological or genetic interventions that target dysregulated ion channels effectively restore neuronal excitability, synaptic function and behavioural phenotypes in FXS animal models. Recent studies further support a role for direct and rapid FMRP-channel interactions in regulating ion channel function. This Review lays out the current state of knowledge in the field regarding channelopathies and the pathogenesis of FXS, including promising therapeutic implications.
Topics: Animals; Channelopathies; Fragile X Mental Retardation Protein; Fragile X Syndrome; Humans
PubMed: 33828309
DOI: 10.1038/s41583-021-00445-9 -
Cytogenetic and Genome Research 2022Brachydactyly mental retardation syndrome (BDMR) typically results from large deletions (>2-9 Mb) in distal 2q37. Haploinsufficiency of HDAC4 with incomplete penetrance...
Brachydactyly mental retardation syndrome (BDMR) typically results from large deletions (>2-9 Mb) in distal 2q37. Haploinsufficiency of HDAC4 with incomplete penetrance has been proposed as the primary genetic cause of BDMR. To date, pure 2q37 deletions distal to HDAC4 were reported only in a limited number of individuals who share a subset of the clinical manifestations seen in cases with 2q37 deletions encompassing HDAC4. Here, we present a 4-year-old African American male who carries the smallest established 2q37.3 deletion distal to HDAC4 (827.1 kb; 16 OMIM genes). His clinical features that overlap with BDMR phenotypes include expressive-receptive language delay, behavioral issues, mild facial dysmorphism such as frontal bossing, and bilateral 5th finger brachydactyly and clinodactyly. The deletion was inherited from his mother with a history of learning difficulties and similar facial dysmorphism. This case provides important genotype-phenotype correlation information and suggests a 2q37 region distal to HDAC4 encompassing the HDLBP gene may contribute to a subset of clinical features overlapping with those seen in individuals with BDMR.
Topics: Male; Humans; Intellectual Disability; Brachydactyly; Chromosome Deletion; Genetic Association Studies; Phenotype; Chromosomes, Human, Pair 2
PubMed: 36516793
DOI: 10.1159/000526660