Cause Of Intellectual Disability Research Articles

Medicaid Enrollment and Service Use Among Adults With Down Syndrome

Down syndrome is the leading genetic cause of intellectual disability and automatically qualifies individuals for Social Security Insurance. Therefore, Medicaid is the major health insurance provider for a population at high risk for dementia, obesity, and premature mortality. Despite the importance of Medicaid for adults with Down syndrome, little is known about how this population uses Medicaid. To describe enrollment in, health care use in, and cost to Medicaid for adults with Down syndrome compared with adults with intellectual disability and a random sample of adults enrolled in Medicaid. In this cohort study, the data are from a claims cohort of adults aged 18 years or older enrolled in Medicaid at any point between January 1, 2011, and December 31, 2019. Participants were enrollees with 1 or more inpatient claim or 2 or more other claims with an International Classification of Diseases, Ninth Revision code or an International Statistical Classification of Diseases and Related Health Problems, Tenth Revision code for Down syndrome or intellectual disability as well as a random sample of those without developmental disability. Analyses were conducted from June 2022 to February 2023. Data were linked across 2 data reporting systems. Main outcomes were enrollee demographic characteristics, enrollment characteristics, cost, and service use. This cohort study included 123 024 individuals with Down syndrome (820 273 person-years of coverage; mean [SD] age, 35 [14.7] years; median age, 33 years [IQR, 21-48 years]; 51.6% men; 14.1% Black individuals; 16.7% Hispanic individuals; and 74.6% White individuals), 1 182 246 individuals with intellectual disability (mean [SD] age, 37.1 [16.8] years; median age, 33 years [IQR, 22-50 years]; 56.5% men; 22.0% Black individuals; 11.7% Hispanic individuals; and 69.5% White individuals), and 3 176 371 individuals with no developmental disabilities (mean [SD] age, 38 [18.6] years; median age, 33 years [IQR, 21-52 years]; 43.8% men; 23.7% Black individuals; 20.7% Hispanic individuals; and 61.3% White individuals). Median enrollment in Medicaid for a person with Down syndrome was 8.0 years (IQR, 5.0-9.0 years; mean [SD], 6.6 [2.6] years). Costs were higher for the Down syndrome group (median, $26 278 per person-year [IQR, $11 145-$55 928 per person-year]) relative to the group with no developmental disabilities (median, $6173 per person-year [IQR, $868-$58 390 per person-year]). Asian, Black, Hispanic, Native American, and Pacific Islander adults with Down syndrome had fewer costs and claims per person-year compared with White adults with Down syndrome. This cohort study of individuals with Down syndrome enrolled in Medicaid found consistent enrollment and high use of health care in a population with high health care needs. Results were similar comparing individuals with Down syndrome and those with intellectual disability, with both groups differing from a sample of Medicaid enrollees with no developmental disabilities. Medicaid data are a useful tool for understanding the health and well-being of individuals with Down syndrome.

Understanding the genetic mechanisms and cognitive impairments in Down syndrome: towards a holistic approach.

The most common genetic cause of intellectual disability is Down syndrome (DS), trisomy 21. It commonly results from three copies of human chromosome 21 (HC21). There are no mutations or deletions involved in DS. Instead, the phenotype is caused by altered transcription of the genes on HC21. These transcriptional variations are responsible for a myriad of symptoms affecting every organ system. A very debilitating aspect of DS is intellectual disability (ID). Although tremendous advances have been made to try and understand the underlying mechanisms of ID, there is a lack of a unified, holistic view to defining the cause and managing the cognitive impairments. In this literature review, we discuss the mechanisms of neuronal over-inhibition, abnormal morphology, and other genetic factors in contributing to the development of ID in DS patients and to gain a holistic understanding of ID in DS patients. We also highlight potential therapeutic approaches to improve the quality of life of DS patients.

Increased body weight in mice with fragile X messenger ribonucleoprotein 1 (Fmr1) gene mutation is associated with hypothalamic dysfunction

Mutations in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene are linked to Fragile X Syndrome, the most common monogenic cause of intellectual disability and autism. People affected with mutations in FMR1 have higher incidence of obesity, but the mechanisms are largely unknown. In the current study, we determined that male Fmr1 knockout mice (KO, Fmr1−/y), but not female Fmr1−/−, exhibit increased weight when compared to wild-type controls, similarly to humans with FMR1 mutations. No differences in food or water intake were found between groups; however, male Fmr1−/y display lower locomotor activity, especially during their active phase. Moreover, Fmr1−/y have olfactory dysfunction determined by buried food test, although they exhibit increased compulsive behavior, determined by marble burying test. Since olfactory brain regions communicate with hypothalamic regions that regulate food intake, including POMC neurons that also regulate locomotion, we examined POMC neuron innervation and numbers in Fmr1−/y mice. POMC neurons express Fmrp, and POMC neurons in Fmr1−/y have higher inhibitory GABAergic synaptic inputs. Consistent with increased inhibitory innervation, POMC neurons in the Fmr1−/y mice exhibit lower activity, based on cFOS expression. Notably, Fmr1−/y mice have fewer POMC neurons than controls, specifically in the rostral arcuate nucleus, which could contribute to decreased locomotion and increased body weight. These results suggest a role for Fmr1 in the regulation of POMC neuron function and the etiology of Fmr1-linked obesity.

Developmental delays in cortical auditory temporal processing in a mouse model of Fragile X syndrome

BackgroundAutism spectrum disorders (ASD) encompass a wide array of debilitating symptoms, including sensory dysfunction and delayed language development. Auditory temporal processing is crucial for speech perception and language development. Abnormal development of temporal processing may account for the language impairments associated with ASD. Very little is known about the development of temporal processing in any animal model of ASD.MethodsIn the current study, we quantify auditory temporal processing throughout development in the Fmr1 knock-out (KO) mouse model of Fragile X Syndrome (FXS), a leading genetic cause of intellectual disability and ASD-associated behaviors. Using epidural electrodes in awake and freely moving wildtype (WT) and KO mice, we recorded auditory event related potentials (ERP) and auditory temporal processing with a gap-in-noise auditory steady state response (gap-ASSR) paradigm. Mice were recorded at three different ages in a cross sectional design: postnatal (p)21, p30 and p60. Recordings were obtained from both auditory and frontal cortices. The gap-ASSR requires underlying neural generators to synchronize responses to gaps of different widths embedded in noise, providing an objective measure of temporal processing across genotypes and age groups.ResultsWe present evidence that the frontal, but not auditory, cortex shows significant temporal processing deficits at p21 and p30, with poor ability to phase lock to rapid gaps in noise. Temporal processing was similar in both genotypes in adult mice. ERP amplitudes were larger in Fmr1 KO mice in both auditory and frontal cortex, consistent with ERP data in humans with FXS.ConclusionsThese data indicate cortical region-specific delays in temporal processing development in Fmr1 KO mice. Developmental delays in the ability of frontal cortex to follow rapid changes in sounds may shape language delays in FXS, and more broadly in ASD.

Correlating MRI-based brain volumetry and cognitive assessment in people with Down syndrome.

Down syndrome (DS) is the most common genetic cause of intellectual disability. Children and adults with DS show deficits in language performance and explicit memory. Here, we used magnetic resonance imaging (MRI) on children and adults with DS to characterize changes in the volume of specific brain structures involved in memory and language and their relationship to features of cognitive-behavioral phenotypes. Thirteen children and adults with the DS phenotype and 12 age- and gender-matched healthy controls (age range 4-25) underwent an assessment by MRI and a psychological evaluation for language and cognitive abilities. The cognitive profile of people with DS showed deficits in different cognition and language domains correlating with reduced volumes of specific regional and subregional brain structures, confirming previous related studies. Interestingly, in our study, people with DS also showed more significant parahippocampal gyrus volumes, in agreement with the results found in earlier reports. The memory functions and language skills affected in studied individuals with DS correlate significantly with the reduced volume of specific brain regions, allowing us to understand DS's cognitive-behavioral phenotype. Our results provide an essential basis for early intervention and the design of rehabilitation management protocols.

Single-Nucleus Profiling Identifies Accelerated Oligodendrocyte Precursor Cell Senescence in a Mouse Model of Down Syndrome.

Down syndrome (DS), the most common genetic cause of intellectual disability, is associated with lifelong cognitive deficits. However, the mechanisms by which triplication of chromosome 21 genes drive neuroinflammation and cognitive dysfunction are poorly understood. Here, using the Ts65Dn mouse model of DS, we performed an integrated single-nucleus ATAC and RNA-sequencing (snATAC-seq and snRNA-seq) analysis of the adult cortex. We identified cell type-specific transcriptional and chromatin-associated changes in the Ts65Dn cortex, including regulators of neuroinflammation, transcription and translation, myelination, and mitochondrial function. We discovered enrichment of a senescence-associated transcriptional signature in Ts65Dn oligodendrocyte (OL) precursor cells (OPCs) and epigenetic changes consistent with a loss of heterochromatin. We found that senescence is restricted to a subset of OPCs concentrated in deep cortical layers. Treatment of Ts65Dn mice with a senescence-reducing flavonoid rescued cortical OPC proliferation, restored microglial homeostasis, and improved contextual fear memory. Together, these findings suggest that cortical OPC senescence may be an important driver of neuropathology in DS.

Reliability of resting-state electrophysiology in fragile X syndrome

ObjectiveFragile X Syndrome (FXS) is the leading monogenic cause of intellectual disability and autism spectrum disorder. Currently, there are no established biomarkers for predicting and monitoring drug effects in FXS, and no approved therapies are available. Previous studies have shown electrophysiological changes in the brain using electroencephalography (EEG) in individuals with FXS and animal models. These changes may be influenced by drug therapies. In this study, we aimed to assess the reliability of resting-state EEG measures in individuals with FXS, which could potentially serve as a biomarker for drug discovery. MethodsWe collected resting-state EEG data from 35 individuals with FXS participating in placebo-controlled clinical trials (23 males, 12 females; visit age mean+/-std 25.6 +/−8.3). The data were analyzed for various spectral features using intraclass correlation analysis to evaluate test-retest reliability. The intervals between EEG recordings ranged from same-day measurements to up to six weeks apart. ResultsOur results showed high reliability for most spectral features, with same-day reliability exceeding 0.8. Features of interest demonstrated ICC values of 0.60 or above at longer intervals. Among the features, alpha band relative power exhibited the highest reliability. ConclusionThese findings indicate that resting-state EEG can provide consistent and reproducible measures of brain activity in individuals with FXS. This supports the potential use of EEG as an objective biomarker for evaluating the effects of new drugs in FXS. SignificanceThe reliable measurements obtained from power spectrum-based resting-state EEG make it a promising tool for assessing the impact of small molecule drugs in FXS.

Lipopolysaccharide-induced sickness behavior is not altered in male Fmr1-deficient mice.

Fragile X syndrome is the main monogenetic cause of intellectual disability and autism. Alterations in the immune system are commonly found in these developmental disorders. We and others have demonstrated that Fmr1 mutant mice present an altered response to immune stimuli. However, whether this altered immune response can influence the Fmr1 mutant behavioral outcomes in response to inflammation has not been fully investigated. In the current study, we examine the behavioral sickness response of male wildtype and knockout mice to the innate immune stimulus lipopolysaccharide (LPS) (0.1mg/kg) to determine if Fmr1 mutants have altered sickness behavior. We used an enzyme-linked immunosorbent assay (ELISA) to measure changes in the cytokine interleukin-6 (IL-6) to determine that inflammation was induced in the mice. Sickness behavior was assessed in a wheel-running paradigm, and a tail suspension test was used to assess the depressive-like phenotype that follows sickness behavior in response to LPS. The ELISA using blood serum confirmed a significant increase in IL-6 in mice that were treated with LPS. Treated Fmr1 mutants exhibited decreased distance traveled in the wheel running after LPS administration, similar to treated controls. Another cohort of animals treated with LPS were tested in the tail suspension test and exhibited no alterations in immobility time in response to LPS. Together, our data suggest that Fmr1 mutant mice do not have altered sickness behavior in response to a low dose of LPS.

Comprehensive volumetric phenotyping of the neonatal brain in Down syndrome.

Down syndrome (DS) is the most common genetic cause of intellectual disability with a wide range of neurodevelopmental outcomes. To date, there have been very few in vivo neuroimaging studies of the neonatal brain in DS. In this study we used a cross-sectional sample of 493 preterm- to term-born control neonates from the developing Human Connectome Project to perform normative modeling of regional brain tissue volumes from 32 to 46weeks postmenstrual age, accounting for sex and age variables. Deviation from the normative mean was quantified in 25 neonates with DS with postnatally confirmed karyotypes from the Early Brain Imaging in DS study. Here, we provide the first comprehensive volumetric phenotyping of the neonatal brain in DS, which is characterized by significantly reduced whole brain, cerebral white matter, and cerebellar volumes; reduced relative frontal and occipital lobar volumes, in contrast with enlarged relative temporal and parietal lobar volumes; enlarged relative deep gray matter volume (particularly the lentiform nuclei); and enlargement of the lateral ventricles, amongst other features. In future, the ability to assess phenotypic severity at the neonatal stage may help guide early interventions and, ultimately, help improve neurodevelopmental outcomes in children with DS.

Further evidence of biallelic variants in KCNK18 as a cause of intellectual disability and epilepsy with febrile seizure plus.

KCNK18 , a potassium channel subfamily K member 18 (MIM*613655), encodes for TWIK-related spinal cord K+ channel (TRESK) and is important for maintaining neuronal excitability. Monoallelic variants in KCNK18 are known to cause autosomal dominant migraine, with or without aura, susceptibility to, 13 (MIM#613656). Recently, biallelic missense variants in KCNK18 have been reported in three individuals from a non-consanguineous family with intellectual disability, developmental delay, autism spectrum disorder (ASD), and seizure. Singleton exome sequencing was performed for the proband after detailed clinical evaluation to identify the disease-causing variants in concordance with the phenotype. We herein report an individual with intellectual disability, developmental delay, ASD, and epilepsy with febrile seizure plus with a novel homozygous stopgain variant, c.499C>T p.(Arg167Ter) in KCNK18 . This report further validates KCNK18 as a cause of autosomal recessive intellectual disability, epilepsy, and ASD.

Differential Effects of a Behavioral Treatment Probe on Social Gaze Behavior in Fragile X Syndrome and Non-Syndromic Autism Spectrum Disorder.

The purpose of this study was to examine potential differences in social learning between individuals with fragile X syndrome (FXS), the leading known inherited cause of intellectual disability, and individuals with non-syndromic autism spectrum disorder(ASD). Thirty school-aged males with FXS and 26 age and symptom-matched males with non-syndromic ASD, were administered a behavioral treatment probe designed to improve levels of social gaze during interactions with others. The treatment probe was administered by a trained behavior therapist over two days in our laboratory and included reinforcement of social gaze in two alternating training conditions - looking while listening and looking while speaking. Prior to each session, children in each group were taught progressive muscle relaxation and breathing techniques to counteract potential increased hyperarousal. Measures included the rate of learning in each group during treatment, in addition to levels of social gaze and heart rate obtained during administration of a standardized social conversation task administered prior to and following the treatment probe. Results showed that learning rates obtained during administration of the treatment probe were significantly less steep and less variable for males with FXS compared to males with non-syndromic ASD. Significant improvements in social gaze were also observed for males with FXS during the social conversation task. There was no effect of the treatment probe on heart rate in either group. These data reveal important differences in social learning between the two groups and have implications for early interventions in the two conditions.

Emergence of Treadmill Running Ability and Quantitative Assessment of Gait Dynamics in Young Ts65Dn Mice: A Mouse Model for Down Syndrome.

Down syndrome (DS), which results from the complete or partial trisomy of chromosome 21 (trisomy-21), is the most common genetically defined cause of intellectual disability. Trisomy-21 also produces, or is associated with, many neurodevelopmental phenotypes and neurological comorbidities, including delays and deficits in fine and gross motor development. The Ts65Dn mouse is the most studied animal model for DS and displays the largest known subset of DS-like phenotypes. To date, however, only a small number of developmental phenotypes have been quantitatively defined in these animals. Here, we used a commercially available high-speed, video-based system to record and analyze the gait of Ts65Dn and euploid control mice. Longitudinal treadmill recordings were performed from p17 to p35. One of the main findings was the detection of genotype- and sex-dependent developmental delays in the emergence of consistent, progressive-intensity gait in Ts65Dn mice when compared to control mice. Gait dynamic analysis showed wider normalized front and hind stances in Ts65Dn mice compared to control mice, which may reflect deficits in dynamic postural balance. Ts65Dn mice also displayed statistically significant differences in the variability in several normalized gait measures, which were indicative of deficits in precise motor control in generating gait.

Neurodevelopmental profile of children with congenital hypothyroidism at 18–42 months of age: A case study from South India

Objectives: Congenital hypothyroidism (CH) is the most common preventable cause of intellectual disability in the world. It has been shown in multiple studies that with early detection and treatment of CH normal cognitive function is attainable. The Bayley scales of infant development (BSID) have been used extensively to evaluate the developmental functioning and to assist in planning of treatment for infants with neurodevelopmental delays or disabilities. The aim of the study was to assess the neuromotor and neurocognitive development of children with CH and to correlate it with treatment initiation, duration, and normalization of thyroid stimulating hormone (TSH) post-replacement therapy. Material and Methods: This was a cross-sectional study, where children with diagnosed CH were selected from two tertiary care centers. The children aged between 18 and 42 months were called for the neurodevelopmental assessment using BSID-III. Results: A total of 53 children diagnosed with CH were enrolled. The mean age of children was 29.53 ± 8.7 months during the study. On evaluating the children, mean cognitive composite score (CS) was 102.83 ± 12.77. Mean language CS was 106.55 ± 19.47. Mean motor CS was 111.45 ± 16.4. We noticed that there was statistically significant negative correlation between time for normalization of TSH and BSID-III motor score (P = 0.03). There was no statistically significant correlation between day of initiation of treatment, initial TSH level, or dose of levothyroxine to the BSID-III (P > 0.05). Conclusion: Neurodevelopmental retardation has been detected in children with CH in whom time taken for normalization of TSH was longer. Babies diagnosed with CH should be under regular follow-up for evaluation of neuromotor developmental status by a multidisciplinary team.

Dodecyl creatine ester improves cognitive function and identifies key protein drivers including KIF1A and PLCB1 in a mouse model of creatine transporter deficiency.

Creatine transporter deficiency (CTD), a leading cause of intellectual disability is a result of the mutation in the gene encoding the creatine transporter SLC6A8, which prevents creatine uptake into the brain, causing mental retardation, expressive speech and language delay, autistic-like behavior and epilepsy. Preclinical in vitro and in vivo data indicate that dodecyl creatine ester (DCE) which increases the creatine brain content, might be a therapeutic option for CTD patients. To gain a better understanding of the pathophysiology and DCE treatment efficacy in CTD, this study focuses on the identification of biomarkers related to cognitive improvement in a Slc6a8 knockout mouse model (Slc6a8-/y) engineered to mimic the clinical features of CTD patients which have low brain creatine content. Shotgun proteomics analysis of 4,035 proteins in four different brain regions; the cerebellum, cortex, hippocampus (associated with cognitive functions) and brain stem, and muscle as a control, was performed in 24 mice. Comparison of the protein abundance in the four brain regions between DCE-treated intranasally Slc6a8-/y mice and wild type and DCE-treated Slc6a8-/y and vehicle group identified 14 biomarkers, shedding light on the mechanism of action of DCE. Integrative bioinformatics and statistical modeling identified key proteins in CTD, including KIF1A and PLCB1. The abundance of these proteins in the four brain regions was significantly correlated with both the object recognition and the Y-maze tests. Our findings suggest a major role for PLCB1, KIF1A, and associated molecules in the pathogenesis of CTD.

Perspectives on adaptive functioning and intellectual functioning measures for intellectual disabilities behavioral research.

Intellectual disability (ID) is a significant limitation in both intellectual ability and adaptive functioning, but many studies of participants with ID only include a measure of overall intellectual functioning when describing their samples. The purpose of this perspective article was to provide a starting point for future research regarding the utility of including measures of both intellectual and adaptive functioning in research focused on ID. In this article, we discuss the differences and similarities between the constructs of intellectual and adaptive functioning, how they are measured, and the benefits of using both measures to describe participant abilities. Data are presented to demonstrate that intellectual and adaptive functioning measures capture separate but related skills in a sample of individuals with ID (i.e., children with Down syndrome [DS]; the leading genetic cause of ID). Thirty children with DS (7-31 months) were administered the Mullen Scales of Early Learning and their mothers were interviewed using the Vineland Adaptive Behavior Scales. At the group level, Vineland and Mullen composite scores were relatively normally distributed and positively correlated. At the individual level, a concordance correlation coefficient indicated moderate agreement between Vineland and Mullen composite scores. Although many children showed consistency between measures, others did not. Our discussion and findings, though preliminary, highlight that intellectual and adaptive functioning are separate but related skills and that there are benefits to including both measures when describing samples with ID. We discuss considerations for including adaptive functioning measures to enhance future research on individuals with ID.

Intellectual disabilities and autism among children with congenital heart defects, Western Australia, 1983–2010

BackgroundChildren with congenital heart defects (CHDs) are at higher risk of developing an intellectual disability. However, severity of intellectual disabilities among this group of children are largely unknown. Our objective was to determine the risk of intellectual disability (ID), ID severity, and autism among children with CHDs.MethodsWe conducted a retrospective cohort study of singleton live births in Western Australia (n = 20,592) between 1983 and 2010. Children with CHDs were identified from the Western Australian Register for Developmental Anomalies (n = 6563) and infants without CHDs were randomly selected from state birth records (n = 14,029). Children diagnosed with ID before 18 years were identified by linkage to statewide Intellectual Disability Exploring Answers database. Odds ratios (OR) and 95% confidence intervals (CI) were calculated from logistic regression models for all CHDs combined and by CHD severity adjusting for potential confounders.ResultsOf 20,592 children, 466 (7.1%) with CHDs and 187 (1.3%) without CHDs had an ID. Compared to children without CHDs, children with any CHD had 5.26 times (95% CI 4.42, 6.26) the odds of having an ID and 4.76 times (95% CI 3.98, 5.70) the odds of having mild/moderate ID. Children with any CHD had 1.76 times the odds of having autism (95% CI 1.07, 2.88), and 3.27 times the odds of having an unknown cause of ID (95% CI 2.65, 4.05) compared to children without CHD. The risk of having autism (aOR 3.23, 95% CI 1.11, 9.38), and unknown cause of ID (aOR 3.45, 95% CI 2.09, 5.70) was greatest for children with mild CHD.ConclusionsChildren with CHDs were more likely to have an ID or autism. Future research should elucidate underlying etiology of ID in children with CHDs.

Co-occurring conditions in children with Down syndrome and autism: a retrospective study

BackgroundDown syndrome (DS) is one of the most common genetic causes of intellectual disability, and it is associated with an increased incidence of numerous co-occurring conditions. Autism spectrum disorder (ASD) is common in persons with DS, with rates reported as high as 39%. However, little is known regarding co-occurring conditions in children with both DS and ASD.MethodsA single-center retrospective review of prospective longitudinally collected clinical data was performed. Any patient with a confirmed diagnosis of DS evaluated at a large, specialized Down Syndrome Program in a tertiary pediatric medical center between March 2018 and March 2022 was included. A standardized survey which included demographic and clinical questions was administered during each clinical evaluation.ResultsIn total, 562 individuals with DS were included. The median age was 10 years (IQR: 6.18–13.92). Of this group, 72 (13%) had a co-occurring diagnosis of ASD (DS+ASD). Individuals with DS+ASD were more likely to be male (OR 2.23, CI 1.29–3.84) and had higher odds of a current or prior diagnosis of constipation (OR 2.19, CI 1.31–3.65), gastroesophageal reflux (OR 1.91, CI 1.14–3.21), behavioral feeding difficulties (OR 2.71, CI 1.02–7.19), infantile spasms (OR 6.03, CI 1.79–20.34) and scoliosis (OR 2.73, CI 1.16–6.40). There were lower odds of congenital heart disease in the DS+ASD group (OR 0.56, CI 0.34–0.93). There was no observed difference in prematurity or Neonatal Intensive Care Unit complications between groups. Individuals with DS+ASD had similar odds of having a history of congenital heart defect requiring surgery to those with DS only. Furthermore, there was no difference in rates of autoimmune thyroiditis or celiac disease. There was also no difference in rates of diagnosed co-occurring neurodevelopmental or mental health conditions in this cohort, including anxiety disorders and attention-deficit/hyperactivity disorder.ConclusionsThis study identifies a variety of medical conditions which are more frequent in children with DS+ASD than DS alone, providing important information for the clinical management of these patients. Future research should investigate the role of some of these medical conditions in the development of ASD phenotypes, and whether there may be distinct genetic and metabolic contributions towards these conditions.

Diagnostic yield of chromosomal microarray and trio whole exome sequencing in congenital brain anomalies

IntroductionThe deductive method: from karyotyping to aCGH and WES is an important aspect in the diagnosis and search for the causes of intellectual disability due to congenital brain anomalies. There is recommendation to exclude the presence of CNV or monogenic variants for patients with a normal karyotype, but with a clinical picture of syndromic disease.ObjectivesImprovement of diagnosis of intellectual disability.MethodsaCGH with 60K Agilent microarrays, WES with SureSelect Human All Exon V8ResultsPathogenic or potentially pathogenic CNVs were excluded previously by aCGH for 10 families (total 32 people, 2 families had 2 children) with intellectual disability and congenital brain anomalies (for example, polymicrogyria, pachygyria, lissencephaly). The WES identified candidate variants for all families that can lead to impaired neurodevelopment, including 3 pathogenic variants in 3 families, 3 likely pathogenic in three other families, and 10 variants with uncertain clinical significance for 4 families. Almost all of these variants were identified de novo, except for one family, where the proband has been a compound heterozygous for two variants in the RELN gene. The first case of pathogenic mutation de novo was detected in a girl with agenesis of the corpus callosum. It was a missense mutation DYNC1H1 (NM_001376.5): c.4868G>A (p.Arg1623Gln), which leads to impaired intellectual development in autosomal dominant type 13 (OMIM 614563). The second variant was detected in a boy with corpus callosum agenesis, pontine hypogenesis, pachygyria in the frontal lobes. It was a missense variant MACF1 (ENST00000567887.5): c.21989A>G(p.Asp7330Gly), which leads to lissencephaly 9 with complex brainstem malformation (OMIM 614563). The third variant was found in a girl with epilepsy and impaired myelination of the white matter of the parietal-occipital areas of the cerebral hemispheres. It was a missense variant CDKL5 (NM_001323289.2):c.404-1G>A that leads to developmental and epileptic encephalopathy 2 (OMIM 300672).ConclusionsSixteen candidate variants potentially responsible for mental health were reported in this study. Most of these variants were missense changes in genes. All except one anomalies arisen de novo. Trio-based WES has been shown to be an important step in making a genetic diagnosis if other chromosomal and subchromosomal abnormalities had been excluded. The clinical description of the patient is the most important step for the correct interpretation of WES results, which allows to establish the exact genetic cause of the disease if several variants with unclear clinical significance were previously identified.This study was supported by the Russian Science Foundation, grant 21-65-00017, https://rscf.ru/project/21-65-00017/Disclosure of InterestNone Declared

Combined whole exome sequencing and chromosomal microarray analysis improve clinical interpretation of genomic variants in patients with intellectual disability

IntroductionaCGH determines pathogenic copy number variations (CNVs) in about 10% of patients with intellectual disability (ID). In another 20% of patients, probably pathogenic CNVs or variants with uncertain clinical significance are detected. It may be variants that do not fully explain the patient’s symptoms, aberrations with reduced penetrance or inherited from healthy parents. The use of a sequencing method for such cases is advisable.ObjectivesImprovement of diagnosis of intellectual disability.MethodsaCGH with 60K Agilent microarrays, qPCR, targeted sequencing, whole exome sequencing (WES).Results Six patients with ID and inherited deletions/duplications detected by aCGH and their parents if available were further examined by sequencing. Four patients had maternal CNVs: (1) del1q41 (SPATA17, LINC00210, RRP15), (2) del7q35 (TCAF2, exon 8), (3) dup8p22p21.3 (PSD3, exons 1-11), and (4) del12p11.1 (SYT10, exons 1-2). Two patients had paternal CNVs: (5) dup1q44 (SMYD3, exons 2-5) and (6) del15q11.2 (TUBGCP5, CYFIP1, NIPA1, NIPA2, LOC283683). The severe phenotype of patient (5) with dup1q44 could not be explained by the paternally inherited disruption of the single SMYD3 gene. WES determined probably pathogenic SNV in the MID1 gene associated with Opitz GBBB syndrome (OMIM 300000), which corresponds better to the patient’s phenotype and is likely to be the cause of the disease. Although del1q41 is included in the region of chromosome 1q41-q42 deletion syndrome (OMIM 612530) the phenotype of the patient (1) is much milder; WES in the patient detected two pathogenic (MPO, MAN2C1) and one probably pathogenic (ARID1B) SNVs. In patient (6) with del15q11.2 pat WES detected additional pathogenic SNV in exon 7 of the ARSE gene. In patient (3) with dup8p22p21.3 WES determined two SNVs with uncertain significance in the KIDINS220, FOXG1 genes. No SNVs were detected by WES in patient (2) with del7q35. For patient (4) with del12p11.1 targeted SYT10 sequencing revealed no pathogenic SNVs as well.ConclusionsSometimes aCGH-analysis is sufficient to identify the causes of ID, however, in the case of detection of CNVs with uncertain clinical significance and/or inherited from healthy parents, it may be necessary to further examine the patient using sequencing methods. So, the accurate diagnosis was made by WES for one patient of eight. For another two patients the combination of CNVs and SNPs should be considered. For the last three patients the described aberrations could not explain the phenotype and whole genome sequencing may be the solution.This study was supported by the Russian Science Foundation, grant 21-65-00017, https://rscf.ru/project/21-65-00017/Disclosure of InterestNone Declared

Maternal hypothyroidism to congenital hypothyroidism in neonates and neonatal outcomes

Introduction: Hypothyroidism is widely prevalent in pregnant women and the rate of detection, especially on a developing country like India, has not kept pace with the magnitude of the problem (1).Since hypothyroidism is easily treated, timely detection and treatment of the disorder could reduce the burden of adverse fetal and maternal outcomes, which are very commonly encountered (1).Congenital hypothyroidism can be caused due to thyroid dysgenesis, disorders of thyroid hormone synthesis, iodine deficiency or excess as well as trans-placental transfer of maternal antibodies or medications. (1). Congenital hypothyroidism is a preventable cause of intellectual disability. Hence it is important to monitor neonates born to mothers with hypothyroidismHypothyroidism is widely prevalent in pregnant women and the rate of detection, especially in a developing country like India needs to be treated and detected early (3).Aims and Objectives: To detect and prevent congenital hypothyroidism in neonates born to mothers with hypothyroidism and their neonatal outcomes. To screen the neonates for congenital hypothyroidism.Methods: All the pregnant women visiting the antenatal OPD at KIMS Narketpally were screened for hypothyroidism during the first antenatal visit.The present study was conducted on 27 women with the diagnosis of hypothyroidism in pregnancy who came to the antenatal OPD and who were delivered at KIMS Narketpally.The neonates born to these mothers were screened for hypothyroidism on day 5 of life in order to detect congenital hypothyroidism in the neonate.Results: In the present study all the 27 mothers diagnosed with Hypothyroidism in pregnancy were taken. The TSH value of most of the mothers with Hypothyroidism was between 3 to 4.9 and most of the mothers were controlled on treatment with Tab.Thyronorm 25mcg.The neonates born to these mothers were screened on Day 5 of life to detect congenital Hypothyroidism. In the present study it showed that none of the neonates born to these Hypothyroid mothers had congenital hypothyroidism because of early diagnosis and Treatment of the mothers in the antenatal period.Conclusion: In the present study it was observed that all the neonates born to the mothers with Hypothyroidism had normal TSH values and none of the neonates had congenital hypothyroidism dues to early diagnosis and treatment.