Mathematical learning disabilities in children with 22q11.2 deletion syndrome: a review

Extent of magnitude representation deficit and relationship with arithmetic skills in children with 22q11.2DS

BACKGROUND

Previous studies have produced conflicting results concerning the extent of magnitude representation deficit and its relationship with arithmetic achievement in children with 22q11.2 deletion syndrome. More specifically, it remains unclear whether deficits are restricted to visuospatial content or are more general and whether they could explain arithmetical impairment.

METHODS

Fifteen 5- to 12-year-old children with 22q11.2 deletion syndrome and 23 age-matched healthy controls performed a non-symbolic magnitude comparison task. Depending on the trial, participants had to compare stimuli with high or low visuospatial load (visuospatial stimuli or temporal sequence of visual stimuli). The participants also completed a battery of arithmetic skills (ZAREKI-R) and a battery of global cognitive functioning (WISC-V or WPPSI-IV), from which working memory and visuospatial indices were derived.

RESULTS

Children with 22q11.2DS responded as fast as healthy controls did but received fewer correct responses, irrespective of visuospatial load. In addition, their performance in the non-symbolic magnitude comparison task did not correlate with the ZAREKI total score, while the working memory index did.

CONCLUSION

Children with 22q11.2DS might suffer from a global magnitude representation deficit rather than a specific deficit due to visuospatial load. However, this deficit alone does not seem to be related to arithmetic achievement. Working memory might be a better concern of interest in favoring arithmetic skills in patients with 22q11.2 deletion syndrome.

TRIAL REGISTRATION

Clinicaltrials, NCT04373226 . Registered 16 September 2020.

Neurobiology of numerical learning

Numerical abilities are complex cognitive skills essential for dealing with requirements of the modern world. Although the brain structures and functions underlying numerical cognition in different species have long been appreciated, genetic and molecular techniques have more recently expanded the knowledge about the mechanisms underlying numerical learning. In this review, we discuss the status of the research related to the neurobiological bases of numerical abilities. We consider how genetic factors have been associated with mathematical capacities and how these link to the current knowledge of brain regions underlying these capacities in human and non-human animals. We further discuss the extent to which significant variations in the levels of specific neurotransmitters may be used as potential markers of individual performance and learning difficulties and take into consideration the therapeutic potential of brain stimulation methods to modulate learning and improve interventional outcomes. The implications of this research for formulating a more comprehensive view of the neural basis of mathematical learning are discussed.

Updated clinical practice recommendations for managing children with 22q11.2 deletion syndrome

This review aimed to update the clinical practice guidelines for managing children and adolescents with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society, the international scientific organization studying chromosome 22q11.2 differences and related conditions, recruited expert clinicians worldwide to revise the original 2011 pediatric clinical practice guidelines in a stepwise process: (1) a systematic literature search (1992-2021), (2) study selection and data extraction by clinical experts from 9 different countries, covering 24 subspecialties, and (3) creation of a draft consensus document based on the literature and expert opinion, which was further shaped by survey results from family support organizations regarding perceived needs. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text reviews, including 1545 meeting criteria for potential relevance to clinical care of children and adolescents. Informed by the available literature, recommendations were formulated. Given evidence base limitations, multidisciplinary recommendations represent consensus statements of good practice for this evolving field. These recommendations provide contemporary guidance for evaluation, surveillance, and management of the many 22q11.2DS-associated physical, cognitive, behavioral, and psychiatric morbidities while addressing important genetic counseling and psychosocial issues.

The Cognitive Profile of Math Difficulties: A Meta-Analysis Based on Clinical Criteria

Math difficulties (MD) manifest across various domain-specific and domain-general abilities. However, the existing cognitive profile of MD is incomplete and thus not applicable in typical settings such as schools or clinics. So far, no review has applied inclusion criteria according to DSM or ICD, summarized domain-specific abilities or examined the validity of response time scores for MD identification. Based upon stringent clinical criteria, the current meta-analysis included 34 studies which compared cognitive performances of a group with MD (n = 680) and a group without MD (n = 1565). Criteria according to DSM and ICD were applied to identify MD (percentile rank ≤ 16, age range 8–12 years, no comorbidities/low IQ). Effect sizes for 22 abilities were estimated and separated by their level and type of scoring (AC = accuracy, RT = response time). A cognitive profile of MD was identified, characterized by distinct weaknesses in: (a) computation (calculation [AC], fact retrieval [AC]), (b) number sense (quantity processing [AC], quantity-number linking [RT], numerical relations [AC]), and (c) visual-spatial short-term storage [AC]. No particular strength was found. Severity of MD, group differences in reading performance and IQ did not significantly moderate the results. Further analyses revealed that (a) effects are larger when dealing with numbers or number words than with quantities, (b) MD is not accompanied by any weakness in abilities typically assigned to reading, and (c) weaknesses in visual-spatial short-term storage emphasize the notion that number and space are interlinked. The need for high-quality studies investigating domain-general abilities is discussed.

Cognitive Dimensions of Learning in Children With Problems in Attention, Learning, and Memory

A data-driven, transdiagnostic approach was used to identify the cognitive dimensions linked with learning in a mixed group of 805 children aged 5 to 18 years recognised as having problems in attention, learning and memory by a health or education practitioner. Assessments included phonological processing, information processing speed, short-term and working memory, and executive functions, and attainments in word reading, spelling, and maths. Data reduction methods identified three dimensions of phonological processing, processing speed and executive function for the sample as a whole. This model was comparable for children with and without ADHD. The severity of learning difficulties in literacy was linked with phonological processing skills, and in maths with executive control. Associations between cognition and learning were similar across younger and older children and individuals with and without ADHD, although stronger links between learning-related problems and both executive skills and processing speed were observed in children with ADHD. The results establish clear domain-specific cognitive pathways to learning that distinguish individuals in the heterogeneous population of children struggling to learn.

Longitudinal Psychiatric and Developmental Outcomes in 22q11.2 Deletion Syndrome: A Systematic Review

OBJECTIVE

22q11.2 deletion syndrome (22q11DS) is a common genetic deletion syndrome associated with psychiatric disorders and developmental delays. A significant amount of 22q11DS research literature is published annually; here, we focus exclusively on longitudinal data that have been published in the past 5 years regarding psychiatric disorders and/or cognitive and social development. After a review, areas for future research consideration and clinical recommendations are presented.

METHODS

Articles were reviewed and organized in adherence with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for conducting systematic reviews. The literature search identified 852 studies, and 22 studies met inclusion criteria.

RESULTS

Longitudinal study findings indicate that developmental considerations for youth with 22q11DS should focus on the primacy and enduring nature of social and executive functioning deficits, attention-deficit/hyperactivity disorder, anxiety, and negative symptoms of psychosis.

CONCLUSION

From the diathesis of physiological conditions and genetic variance, 22q11DS and its associated phenotype of persistent cognitive deficits, comorbid psychiatric disorders, and social impairments likely conspire to increase the risk for stress in adolescence. The diathesis-stress framework, along with chronic stress, increases psychosis risk in individuals with 22q11DS. The existing literature has a heavy focus on the impact of the deletion on individual skills and attributes, such as cognition, but lacks information on the impact of the environment. Future 22q11DS research should consider specific aspects of social functioning, including interactions with parenting styles and family communication, as well as high demands in educational settings, as possible risk factors for psychosis.

The Polygenic Nature and Complex Genetic Architecture of Specific Learning Disorder

Specific Learning Disorder (SLD) is a multifactorial, neurodevelopmental disorder which may involve persistent difficulties in reading (dyslexia), written expression and/or mathematics. Dyslexia is characterized by difficulties with speed and accuracy of word reading, deficient decoding abilities, and poor spelling. Several studies from different, but complementary, scientific disciplines have investigated possible causal/risk factors for SLD. Biological, neurological, hereditary, cognitive, linguistic-phonological, developmental and environmental factors have been incriminated. Despite worldwide agreement that SLD is highly heritable, its exact biological basis remains elusive. We herein present: (a) an update of studies that have shaped our current knowledge on the disorder’s genetic architecture; (b) a discussion on whether this genetic architecture is ‘unique’ to SLD or, alternatively, whether there is an underlying common genetic background with other neurodevelopmental disorders; and, (c) a brief discussion on whether we are at a position of generating meaningful correlations between genetic findings and anatomical data from neuroimaging studies or specific molecular/cellular pathways. We conclude with open research questions that could drive future research directions.

Relations between executive functions and academic outcomes in elementary school children: A meta-analysis

The primary goal of this study was to examine developmental patterns among the relations between components of executive function (EF; working memory [WM], inhibitory control, shifting), and academic outcomes (reading, mathematics, language) in elementary school-age children. These relations were examined within the context of the development of EF and of academic skills utilizing an extension of the unity and diversity, intrinsic cognitive load, and dual process theories. Using meta-analytic methods, we summarized results from 299 studies from 293 articles/dissertations, representing 65,605 elementary school-age children (42-191 months old [M = 101 months, SD = 24.49 months]). Results indicated that accounting for general EF (by including the correlations among EF tasks in meta-analytic path models and accounting for effects between all three EF components and academic outcomes simultaneously) produced weaker relations between EF and academic skills than the bivariate relations which have been reported in prior meta-analytic reviews. However, although reduced, all relations between EF and academic outcomes remained significant throughout elementary school. Whereas WM was consistently moderately associated with reading, math, and oral language across development, the developmental trends for the relations between inhibitory control and shifting with academic outcomes varied based upon the academic skill examined. On the academic side, whereas the relations between reading and language skills with EF components varied throughout elementary school, few developmental changes were found in the relations between EF components and math skills across elementary school. Future directions and implications of findings for the conceptualization of the impact of EF on academics are discussed within the context of relevant theoretical models. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Arithmetic in developmental cognitive disabilities

This paper reviews and discusses research on arithmetical strengths and weaknesses in children with specific developmental cognitive disabilities. It focusses on children with dyslexia, developmental language disorder, attention deficit hyperactivity disorder and autism. In general, studies show that arithmetical weaknesses are commoner in children with any of these disorders than in controls. Autism is sometimes associated with specific strengths in arithmetic; but even in autism, it is commoner for arithmetic to be a relative weakness than a relative strength. There may be some genetic reasons why there is an overlap between mathematical difficulties and other developmental learning difficulties; but much of the reason seems to be that specific aspects of arithmetic are often influenced by other factors, including language comprehension, phonological awareness, verbal and spatial working memory and long-term memory, and executive functions. The findings discussed here will be discussed in relation to Pennington's (2006) Multiple Deficit Model.

Consequences of 22q11.2 Microdeletion on the Genome, Individual and Population Levels

Chromosomal 22q11.2 deletion syndrome (22q11.2DS) (ORPHA: 567) caused by microdeletion in chromosome 22 is the most common chromosomal microdeletion disorder in humans. Despite the same change on the genome level, like in the case of monozygotic twins, phenotypes are expressed differently in 22q11.2 deletion individuals. The rest of the genome, as well as epigenome and environmental factors, are not without influence on the variability of phenotypes. The penetrance seems to be more genotype specific than deleted locus specific. The transcript levels of deleted genes are not usually reduced by 50% as assumed due to haploinsufficiency. 22q11.2DS is often an undiagnosed condition, as each patient may have a different set out of 180 possible clinical manifestations. Diverse dysmorphic traits are present in patients from different ethnicities, which makes diagnosis even more difficult. 22q11.2 deletion syndrome serves as an example of a genetic syndrome that is not easy to manage at all stages: diagnosis, consulting and dealing with.

Magnitude processing in populations with spina-bifida: The role of visuospatial and working memory processes

People with Spina Bifida usually experience difficulties with mathematics. In a series of other developmental disorders, a magnitude processing deficit was considered to be the main source of subsequent difficulties in mathematics. The processing of magnitude could be numerical (which is the larger number) or non-numerical such as spatial (e.g., which is the longer?) or temporal (which one last longer?) for instance. However, no study yet has examined directly magnitude processes in a population with Spina Bifida. On the other hand, recent studies in people with genetic syndromes have suggested that visuospatial and working memory processes play an important role in magnitude processing, including number magnitude. Therefore, in this study we explored for the first time magnitude representation using several tasks with different visuospatial and working memory processing requirements, cognitive skills frequently impaired in Spina Bifida. Results showed children with SB presented a global magnitude processing deficit for non-numerical and numerical comparison tasks, but not in symbolic number magnitude tasks compared to controls. Importantly, visuospatial skills and working memory abilities could partially explain the differences between groups in comparison and estimation tasks. This study proposes that magnitude processing difficulties in children with SB could be due to higher cognitive factors such as visuospatial and working memory processes.

Neurocognitive profile and onset of psychosis symptoms in children, adolescents and young adults with 22q11 deletion syndrome: A longitudinal study

BACKGROUND

The neurobehavioral phenotype of 22q11.2 deletion syndrome (22q11DS) includes cognitive dysfunction and high rates of psychotic symptoms and schizophrenia. Existing research has mainly considered changes in IQ, especially its decline, as a psychosis predictor. The aim of this study was to investigate, in a longitudinal perspective, the relationship between neuropsychological abilities (not only IQ but also executive functioning, language and visual-motor integration abilities) and onset of psychotic symptoms in a sample of children, adolescents and young adults with 22q11DS. In addition, the role of comorbid psychiatric disorders at baseline was taken into account.

METHODS

75 participants with 22q11DS, aged between 6 and 27 years at baseline, were included. Eighteen of the 75 participants had developed psychosis at the one year follow-up (onset psychosis-OP) and constituted the first group; 57 participants who had not developed a psychosis at the one year follow-up (without onset psychosis-WOP) constituted the second group.

RESULTS

At baseline, group OP showed lower IQ (both full scale and verbal and performance scale) and more perseverative errors as well as a reduced number of correct categories on the Wisconsin Card Sorting Test (WCST) compared to group WOP. In addition, at baseline, group OP showed a higher frequency of depressive disorders than group WOP.

CONCLUSION

Even if with caution, results suggest neuropsychological deficits and depressive symptoms should be considered and monitored as possible clinical signs for the onset of psychosis in children, adolescents and young adults with 22q11DS.

The Diagnosis and Treatment of Dyscalculia

BACKGROUND

3-7% of all children, adolescents, and adults suffer from dyscalculia. Severe, persistent difficulty performing arithmetical calculations leads to marked impairment in school, at work, and in everyday life and elevates the risk of comorbid mental disorders. The state of the evidence underlying various methods of diagnosing and treating this condition is unclear.

METHODS

Systematic literature searches were carried out from April 2015 to June 2016 in the PsycInfo, PSYNDEX, MEDLINE, ProQuest, ERIC, Cochrane Library, ICTRP, and MathEduc databases. The main search terms on dyscalculia were the German terms "Rechenstörung," "Rechenschwäche," and "Dyskalkulie" and the English terms "dyscalculia," "math disorder, and "math disability." The data from the retrieved studies were evaluated in a meta-analysis, and corresponding recommendations on the diagnosis and treatment of dyscalculia were jointly issued by the 20 societies and associations that participated in the creation of this guideline.

RESULTS

The diagnosis of dyscalculia should only be made if the person in question displays below-average mathematical performance when seen in the context of relevant information from the individual history, test findings, clinical examination, and further psychosocial assessment. The treatment should be directed toward the individual mathematical problem areas. The mean effect size found across all intervention trials was 0.52 (95% confidence interval [0.42; 0.62]). Treatment should be initiated early on in the primary-school years and carried out by trained specialists in an individual setting; comorbid symptoms and disorders should also receive attention. Persons with dyscalculia are at elevated risk of having dyslexia as well (odds ratio [OR]: 12.25); the same holds for attention deficit/hyperactivity disorder and for other mental disorders, both internalizing (such as anxiety and depression) and externalizing (e.g., disorders characterized by aggression and rule-breaking).

CONCLUSION

Symptom-specific interventions involving the training of specific mathematical content yield the best results. There is still a need for high-quality intervention trials and for suitable tests and learning programs for older adolescents and adults.

The impact of hypocalcemia on full scale IQ in patients with 22q11.2 deletion syndrome

Hypocalcemia has been reported in ~50% of patients 22q11.2DS and calcium regulation is known to play a role in neuronal development and synaptic plasticity. Because calcium ions play a role in neuronal function and development, we hypothesized that hypocalcemia would be associated with adverse effects on full scale IQ index (FSIQ) in patients with 22q11.2DS. A retrospective chart review cataloguing the presence or absence of hypocalcemia in 1073 subjects with a laboratory confirmed chromosome 22q11.2 deletion evaluated at the Children's Hospital of Philadelphia was conducted. 852/1073 patients had an endocrinology evaluation with laboratory confirmed calcium levels. 466/852 (54.7%) had a diagnosis of hypocalcemia. 265/1073 subjects ranging from 0 to 51 years of age had both calcium levels measured and a neuropsychological evaluation yielding a FSIQ. The mean FSIQ for 146/265 patients with hypocalcemia was 77.09 (SD = 13.56) and the mean FSIQ for 119/265 patients with normocalcemia was 77.27 (SD = 14.25). The distribution of patients with intellectual disability (ID) (FSIQ<69), borderline IQ (FSIQ 70-79), and average IQ (FSIQ>80) between the hypocalcemic and normocalcemic groups was not statistically significant (χ2 = 0.2676, p = 0.8748). Neonatal hypocalcemic seizures were not found to be associated with ID. We found no difference in FSIQ between the hypocalcemic and non-hypocalcemic patients with 22q11.2DS. As our findings differ from a previous report in adult subjects, we speculate that this may reflect a potential benefit from early treatment of hypocalcemia and may support early 22q11.2 deletion detection in order to offer prompt diagnosis and subsequent treatment of hypocalcemia.

Neurodevelopmental outcome in 22q11.2 deletion syndrome and management

The 22q11.2 deletion syndrome (22q11.2 DS) places affected individuals at an increased risk for neurodevelopmental/cognitive, behavioral and social-emotional difficulties. Poor cognitive functioning and intellectual disabilities, attention and executive functioning deficits, learning disorders, emotional dysregulation and impairments in social processing are common among individuals with 22q11.2 DS. Identifying risk and protective/resilience factors that can be detected in early life and can predict neurodevelopmental outcomes for people with 22q11.2 DS is of significant clinical relevance and might allow for early detection and intervention. Given the focus of this review, we will discuss the possible contributing factors that influence the neurodevelopmental outcome in 22q1.2 DS, the cognitive phenotype in 22q11.2 DS, the different developmental trajectories across life span, and the implications for clinical practice and management.

22q and two: 22q11.2 deletion syndrome and coexisting conditions

22q11.2 deletion syndrome (DS) is the most frequent copy number variant (CNV) affecting ~1/1,000 fetuses and ~1/2,000-4,000 children, resulting in recognizable but variable findings across multiple organ systems. Patients with atypical features should prompt consideration of coexisting diagnoses due to additional genome-wide mutations, CNVs, or mutations/CNVs on the other allele, unmasking autosomal recessive conditions. Importantly, a dual diagnosis compounds symptoms and impacts management. We previously reported seven patients with 22q11.2DS and: SCID, Trisomy 8 mosaicism, Bernard-Soulier, and CEDNIK syndromes. Here we present six additional unreported patients with 22q11.2DS and concurrent diagnoses. Records on 1,422 patients with 22q11.2DS, identified via FISH, microarray, or MLPA, followed in our 22q and You Center at the Children's Hospital of Philadelphia (CHOP) were reviewed to identify a dual diagnosis. In addition to our seven previously reported cases, we identified an additional six with 22q11.2DS and another coexisting condition identified via: molecular/cytogenetic studies, newborn screening, coagulation factor studies, or enzyme testing; these include CHARGE syndrome (CHD7 mutation), cystic fibrosis, a maternally inherited 17q12 deletion, G6PD deficiency, von Willebrand disease, and 1q21.1 deletion, resulting in an incidence of dual diagnoses at our center of 0.9%. The range of dual diagnoses identified in our cohort is notable, medically actionable, and may alter long-term outcome and recurrence risk counseling. Thus, our findings may support testing patients with 22q11.2DS using a combination of microarray, mutational analysis of the other allele/WES, to ensure appropriate personalized care, as formulating medical management decisions hinges on establishing the correct diagnoses in their entirety.

Reading Deficits in Intellectual Disability Are still an Open Question: A Narrative Review

BACKGROUND

In children with intellectual disability (ID), the acquisition of reading skills constitutes a basic step towards the possibility of independent living, social inclusion and participation.

METHODS

We carried out a narrative review of the literature on reading fluency and accuracy of individuals with ID resulting from different genetic syndromes (Fragile X, Williams, Velocardiofacial, Prader-Willi, and Down syndrome). Our aim was to define their reading profiles in light of the dual-route reading model. For this purpose, studies that examined both word and non-word reading in children with ID were included in the analysis.

RESULTS

Seventeen studies emerged based on the selection criteria. The results were different depending on the control group used. A deficit in reading non-words emerged in studies that used the reading-level match design but not when standardized scores were used, when controls were age-matched or when a mental age matching was used. Thus, a deficit in reading non-words emerged only in studies that used the reading-level match design. However, severe methodological criticisms were recently raised about the use of this matching design.

CONCLUSIONS

In view of the methodological problems in using grade equivalents, it is premature to draw definite conclusions about the reading profile of children with ID resulting from different genetic syndromes. In any case, the reviewed evidence provides little support for the idea that children with ID have selective difficulty in phonological reading. Thus, the reading profile of children with ID remains an open question that needs to be investigated by means of methodologically sound research.

Specific learning disability in mathematics: a comprehensive review

Math skills are necessary for success in the childhood educational and future adult work environment. This article reviews the changing terminology for specific learning disabilities (SLD) in math and describes the emerging genetics and neuroimaging studies that relate to individuals with math disability (MD). It is important to maintain a developmental perspective on MD, as presentation changes with age, instruction, and the different models (educational and medical) of identification. Intervention requires a systematic approach to screening and remediation that has evolved with more evidence-based literature. Newer directions in behavioral, educational and novel interventions are described.

Quantifying indices of short- and long-range white matter connectivity at each cortical vertex

Several neurodevelopmental diseases are characterized by impairments in cortical morphology along with altered white matter connectivity. However, the relationship between these two measures is not yet clear. In this study, we propose a novel methodology to compute and display metrics of white matter connectivity at each cortical point. After co-registering the extremities of the tractography streamlines with the cortical surface, we computed two measures of connectivity at each cortical vertex: the mean tracts’ length, and the proportion of short- and long-range connections. The proposed measures were tested in a clinical sample of 62 patients with 22q11.2 deletion syndrome (22q11DS) and 57 typically developing individuals. Using these novel measures, we achieved a fine-grained visualization of the white matter connectivity patterns at each vertex of the cortical surface. We observed an intriguing pattern of both increased and decreased short- and long-range connectivity in 22q11DS, that provides novel information about the nature and topology of white matter alterations in the syndrome. We argue that the method presented in this study opens avenues for additional analyses of the relationship between cortical properties and patterns of underlying structural connectivity, which will help clarifying the intrinsic mechanisms that lead to altered brain structure in neurodevelopmental disorders.

22q11 deletion syndrome: Parents' and children's experiences of educational and healthcare provision in the United Kingdom

22q11 deletion syndrome (22q11DS) is a genetic syndrome, prevalence around 1:4000-1:6000 live births, with a complex array of associated features, impacting on healthcare and educational support. This study reports the perceptions of families and individuals with 22q11DS in relation to these needs. Individuals and families of those with 22q11DS were approached though two national charities - the Max Appeal and 22Crew. An initial observational survey design was used to gather views via questions probing access to healthcare and educational experiences. Thirty-four responses were received and the data subjected to descriptive analysis. Over half of the respondents were diagnosed before the age of 1. Ninety-one percent reported ongoing difficulties with learning at school, compounded by school attendance being compromised as a result of medical interventions. Individuals reported engaging heavily with educational support and a high number of health professions (mean 9.5; mode 10). Age of diagnosis of 22q11DS ranged from birth to nine years. Families had ongoing concerns about aspects of education and healthcare services, and lack of knowledge and awareness of the difficulties faced by individuals with 22q11DS was raised. Healthcare and education providers should be aware of the range of services individuals required on a regular basis so as to provide a more holistic approach to care.

Longitudinal study of cerebral surface morphology in youth with 22q11.2 deletion syndrome, and association with positive symptoms of psychosis

BACKGROUND

22q11.2 deletion syndrome (22q11DS) is a genetic disorder that greatly increases risk of developing schizophrenia. We previously characterized cerebral surface morphology trajectories from late childhood to mid adolescence in a cohort of youth with 22q11DS. Herein, we extend the study period into early adulthood, and describe further the trajectories associated with severe psychiatric symptoms in this cohort.

METHODS

Participants included 76 youth with 22q11DS and 30 unaffected siblings, assessed at three timepoints, during which high resolution, anatomic magnetic resonance images were acquired. High-dimensional, nonlinear warping algorithms were applied to images in order to derive characteristics of cerebral surface morphology for each participant at each timepoint. Repeated-measures, linear regressions using a mixed model were conducted, while covarying for age and sex.

RESULTS

Alterations in cerebral surface morphology during late adolescence/early adulthood in individuals with 22q11DS were observed in the lateral frontal, orbitofrontal, temporal, parietal, occipital, and cerebellar regions. An Age x Diagnosis interaction revealed that relative to unaffected siblings, individuals with 22q11DS showed age-related surface protrusions in the prefrontal cortex (which remained stable or increased during early adulthood), and surface indentations in posterior regions (which seemed to level off during late adolescence). Symptoms of psychosis were associated with a trajectory of surface indentations in the orbitofrontal and parietal regions.

CONCLUSIONS

These results advance our understanding of cerebral maturation in individuals with 22q11DS, and provide clinically relevant information about the psychiatric phenotype associated with the longitudinal trajectory of cortical surface morphology in youth with this genetic syndrome.

Neuropsychiatric aspects of 22q11.2 deletion syndrome: considerations in the prenatal setting

Most major neuropsychiatric outcomes of concern to families are not detectable by prenatal ultrasound. The introduction of genome-wide chromosomal microarray analysis to prenatal clinical diagnostic testing has increased the detection of pathogenic 22q11.2 deletions, which cause the most common genomic disorder. The recent addition of this and other microdeletions to non-invasive prenatal screening methods using cell-free fetal DNA has further propelled interest in outcomes. Conditions associated with 22q11.2 deletions include intellect ranging from intellectual disability to average, schizophrenia and other treatable psychiatric conditions, epilepsy, and early-onset Parkinson's disease. However, there is currently no way to predict how severe the lifetime expression will be. Available evidence suggests no major role in these neuropsychiatric outcomes for the congenital cardiac or most other structural anomalies that may be detectable on ultrasound. This article provides an outline of the lifetime neuropsychiatric phenotype of 22q11.2 deletion syndrome that will be useful to clinicians involved in prenatal diagnosis and related genetic counselling. The focus is on information that will be most relevant to two common situations: detection of a 22q11.2 deletion in a fetus or newborn, and new diagnosis of 22q11.2 deletion syndrome in a parent without a previous molecular diagnosis. © 2016 John Wiley & Sons, Ltd.

A meta-analysis of math performance in Turner syndrome

AIM

Studies investigating the relationship between Turner syndrome and math learning disability have used a wide variation of tasks designed to test various aspects of mathematical competencies. Although these studies have revealed much about the math deficits common to Turner syndrome, their diversity makes comparisons between individual studies difficult. As a result, the consistency of outcomes among these diverse measures remains unknown. The overarching aim of this review is to provide a systematic meta-analysis of the differences in math and number performance between females with Turner syndrome and age-matched neurotypical peers.

METHOD

We provide a meta-analysis of behavioral performance in Turner syndrome relative to age-matched neurotypical populations on assessments of math and number aptitude. In total, 112 comparisons collected across 17 studies were included.

RESULTS

Although 54% of all statistical comparisons in our analyses failed to reject the null hypothesis, our results indicate that meaningful group differences exist on all comparisons except those that do not require explicit calculation.

INTERPRETATION

Taken together, these results help elucidate our current understanding of math and number weaknesses in Turner syndrome, while highlighting specific topics that require further investigation.

22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common chromosomal microdeletion disorder, estimated to result mainly from de novo non-homologous meiotic recombination events occurring in approximately 1 in every 1,000 fetuses. The first description in the English language of the constellation of findings now known to be due to this chromosomal difference was made in the 1960s in children with DiGeorge syndrome, who presented with the clinical triad of immunodeficiency, hypoparathyroidism and congenital heart disease. The syndrome is now known to have a heterogeneous presentation that includes multiple additional congenital anomalies and later-onset conditions, such as palatal, gastrointestinal and renal abnormalities, autoimmune disease, variable cognitive delays, behavioural phenotypes and psychiatric illness - all far extending the original description of DiGeorge syndrome. Management requires a multidisciplinary approach involving paediatrics, general medicine, surgery, psychiatry, psychology, interventional therapies (physical, occupational, speech, language and behavioural) and genetic counselling. Although common, lack of recognition of the condition and/or lack of familiarity with genetic testing methods, together with the wide variability of clinical presentation, delays diagnosis. Early diagnosis, preferably prenatally or neonatally, could improve outcomes, thus stressing the importance of universal screening. Equally important, 22q11.2DS has become a model for understanding rare and frequent congenital anomalies, medical conditions, psychiatric and developmental disorders, and may provide a platform to better understand these disorders while affording opportunities for translational strategies across the lifespan for both patients with 22q11.2DS and those with these associated features in the general population.

Caracterização do perfil comportamental e de competência social de indivíduos com a síndrome del22q11.2

Resumo:OBJETIVO:caracterizar os problemas comportamentais e de competência social de indivíduos com a síndrome del22q11.2 e compará-los com indivíduos com desenvolvimento típico, segundo informação dos pais.MÉTODOS:participaram desta pesquisa 24 pais de indivíduos de ambos os gêneros, entre seis e 18 anos, sendo 12 indivíduos com a síndrome del22q11.2 (grupo amostral) e 12 indivíduos com desenvolvimento típico (grupo controle). Foi aplicado o inventário comportamental "Child Behavior Checklist (CBCL)".RESULTADOS:oito dos 12 indivíduos com a síndrome foram classificados como "clínico" nas escalas de comportamento e Problemas Internalizantes; cinco dos 12 indivíduos do grupo amostral foram classificados como "clínico" quanto às escalas de comportamento e Problemas Externalizantes. Nas habilidades de competência social, dez dos 12 indivíduos do grupo amostral foram classificados como "clínico".CONCLUSÃO:indivíduos com diagnóstico da síndrome del22q11.2 apresentaram, segundo opinião dos pais, problemas comportamentais e de competência social, em diferentes graus de comprometimento. Quando realizada a comparação entre os grupos pode-se observar diferenças estatisticamente significantes em variáveis dos comportamentos externalizantes e dos comportamentos internalizantes. Desta forma, concluí-se que o grupo amostral apresenta comportamentos mais alterados quando comparados ao grupo controle.

Practical guidelines for managing adults with 22q11.2 deletion syndrome

22q11.2 Deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans, estimated to affect up to 1 in 2,000 live births. Major features of this multisystem condition include congenital anomalies, developmental delay, and an array of early- and later-onset medical and psychiatric disorders. Advances in pediatric care ensure a growing population of adults with 22q11.2DS. Informed by an international panel of multidisciplinary experts and a comprehensive review of the existing literature concerning adults, we present the first set of guidelines focused on managing the neuropsychiatric, endocrine, cardiovascular, reproductive, psychosocial, genetic counseling, and other issues that are the focus of attention in adults with 22q11.2DS. We propose practical strategies for the recognition, evaluation, surveillance, and management of the associated morbidities.Genet Med 17 8, 599-609.

Are 22q11.2 distal deletions associated with math difficulties?

Approximately 6% of school-aged children have math difficulties (MD). A neurogenetic etiology has been suggested due to the presence of MD in some genetic syndromes such as 22q11.2DS. However, the contribution of 22q11.2DS to the MD phenotype has not yet been investigated. This is the first population-based study measuring the frequency of 22q11.2DS among school children with MD. Children (1,564) were identified in the schools through a screening test for language and math. Of these children, 152 (82 with MD and 70 controls) were selected for intelligence, general neuropsychological, and math cognitive assessments and for 22q11.2 microdeletion screening using MLPA. One child in the MD group had a 22q11.2 deletion spanning the LCR22-4 to LCR22-5 interval. This child was an 11-year-old girl with subtle anomalies, normal intelligence, MD attributable to number sense deficit, and difficulties in social interactions. Only 19 patients have been reported with this deletion. Upon reviewing these reports, we were able to characterize a new syndrome, 22q11.2 DS (LCR22-4 to LCR22-5), characterized by prematurity; pre- and postnatal growth restriction; apparent hypotelorism, short/upslanting palpebral fissures; hypoplastic nasal alae; pointed chin and nose; posteriorly rotated ears; congenital heart defects; skeletal abnormalities; developmental delay, particularly compromising the speech; learning disability (including MD, in one child); intellectual disability; and behavioral problems. These results suggest that 22q11.2 DS (LCR22-4 to LCR22-5) may be one of the genetic causes of MD.

Common and specific impairments in attention functioning in girls with chromosome 22q11.2 deletion, fragile X or Turner syndromes

Background

Chromosome 22q11.2 deletion syndrome (22q11.2DS), fragile X syndrome (FXS), and Turner syndrome (TS) are complex and variable developmental syndromes caused by different genetic abnormalities; yet, they share similar cognitive impairments in the domains of numbers, space, and time. The atypical development of foundational neural networks that underpin the attentional system is thought to result in further impairments in higher-order cognitive functions. The current study investigates whether children with similar higher-order cognitive impairments but different genetic disorders also show similar impairments in alerting, orienting, and executive control of attention.

Methods

Girls with 22q11.2DS, FXS, or TS and typically developing (TD) girls, aged 7 to 15 years, completed an attention network test, a flanker task with alerting and orienting cues. Exploration of reaction times and accuracy allowed us to test for potential commonalities in attentional functioning in alerting, orienting, and executive control. Linear regression models were used to test whether the predictors of group and chronological age were able to predict differences in attention indices.

Results

Girls with 22q11.2DS, FXS, or TS demonstrated unimpaired function of the alerting system and impaired function of the executive control system. Diagnosis-specific impairments were found such that girls with FXS made more errors and had a reduced orienting index, while girls with 22q11.2DS showed specific age-related deficits in the executive control system.

Conclusions

These results suggest that the control but not the implementation of attention is selectively impaired in girls with 22q11.2DS, TS or FXS. Additionally, the age effect on executive control in girls with 22q11.2DS implies a possible altered developmental trajectory.

Perceived burden and neuropsychiatric morbidities in adults with 22q11.2 deletion syndrome

BACKGROUND

22q11.2 deletion syndrome (22q11.2DS) is a common genetic subtype of intellectual disability (ID) remarkable for its constellation of congenital, developmental and later-onset features. Survival to adulthood is now the norm, and serious psychiatric illness is common in adults. However, little is known about the experiences and perceived needs of individuals with 22q11.2DS and their caregivers at time of transition from paediatric to adult models of care and beyond.

METHOD

We administered a mail survey to 84 caregivers of adults with 22q11.2DS and 34 adult patients themselves, inquiring about medical and social services, perceived burden and major challenges in adulthood in 22q11.2DS. Standard quantitative and qualitative methods were used to analyse the responses.

RESULTS

Fifty-three (63.1%) caregivers and 20 (58.8%) adults with 22q11.2DS completed the survey. Perceived burden was high, with psychiatric illness and/or behavioural issues considered the most challenging aspects of adulthood in 22q11.2DS by the majority of caregivers (70.0%) and many patients themselves (42.9%). Irrespective of the extent of ID and the presence or absence of other major features, caregivers expressed dissatisfaction with medical and social services for adults, including at time of transition from paediatric care.

CONCLUSIONS

To our knowledge, this is the first study to examine the subjective experiences of adults with 22q11.2DS and their caregivers and to identify their perceived needs for services. Better awareness of 22q11.2DS and its later-onset manifestations, early diagnosis and treatment of psychiatric illness, additional support at time of transition and dedicated clinics for adults with 22q11.2DS may help to improve patient outcomes and reduce caregiver burden.

Association of the family environment with behavioural and cognitive outcomes in children with chromosome 22q11.2 deletion syndrome

BACKGROUND

Children with 22q11.2 deletion syndrome (22q11DS) are at risk for social-behavioural and neurocognitive sequelae throughout development. The current study examined the impact of family environmental characteristics on social-behavioural and cognitive outcomes in this paediatric population.

METHOD

Guardians of children with 22q11DS were recruited through two medical genetics clinics. Consenting guardians were asked to complete several questionnaires regarding their child's social, emotional and behavioural functioning, as well as family social environment and parenting styles. Children with 22q11DS were asked to undergo a cognitive assessment, including IQ and achievement testing, and measures of attention, executive function and memory.

RESULTS

Modest associations were found between aspects of the family social environment and parenting styles with social-behavioural and cognitive/academic outcomes. Regression models indicated that physical punishment, socioeconomic status, parental control and family organisation significantly predicted social-behavioural and cognitive outcomes in children with 22q11DS.

CONCLUSION

Characteristics of the family social environment and parenting approaches appear to be associated with functional outcomes of children with 22q11DS. Understanding the impact of environmental variables on developmental outcomes can be useful in determining more effective targets for intervention. This will be important in order to improve the quality of life of individuals affected by 22q11DS.

Towards a safety net for management of 22q11.2 deletion syndrome: guidelines for our times

The commonest autosomal deletion, 22q11.2 deletion syndrome (22q11DS) is a multisystem disorder varying greatly in severity and age of identification between affected individuals. Holistic care is best served by a multidisciplinary team, with an anticipatory approach. Priorities tend to change with age, from feeding difficulties, infections and surgery of congenital abnormalities particularly of the heart and velopharynx in infancy and early childhood to longer-term communication, learning, behavioural and mental health difficulties best served by evaluation at intervals to consider and initiate management. Regular monitoring of growth, endocrine status, haematological and immune function to enable early intervention helps in maintaining health.

CONCLUSION

Guidelines to best practice management of 22q11DS based on a literature review and consensus have been developed by a national group of professionals with consideration of the limitations of available medical and educational resources.

Caregiver and adult patient perspectives on the importance of a diagnosis of 22q11.2 deletion syndrome

BACKGROUND

Recent advances in genetics are particularly relevant in the field of intellectual disability (ID), where sub-microscopic deletions or duplications of genetic material are increasingly implicated as known or suspected causal factors. Data-driven reports on the impact of providing an aetiological explanation in ID are needed to help justify widespread use of new and expensive genetic technologies.

METHODS

We conducted a survey of caregivers on the value of a genetic/aetiologic diagnosis of 22q11.2 deletion syndrome (22q11.2DS), the most common microdeletion syndrome in ID. We also surveyed the opinion of a high-functioning subset of adults with 22q11.2DS themselves. We used standard quantitative and qualitative methods to analyse the responses.

RESULTS

In total, 73 of 118 surveys were returned (61.9%). There was convergence of quantitative and qualitative results, and consistency between adult patient and caregiver responses. A definitive molecular diagnosis of 22q11.2DS was a critical event with diverse positive repercussions, even if occurring later in life. Frequently cited benefits included greater understanding and certainty, newfound sense of purpose and a platform for advocacy, and increased opportunities to optimise medical, social and educational needs.

CONCLUSIONS

This is the first study to characterise the impact of a diagnosis of this representative microdeletion syndrome on adult patients and their families. The results both validate and expand on the theoretical benefits proposed by clinicians and researchers. The use of genome-wide microarray technologies will provide an increasing number of molecular diagnoses. The importance of a diagnosis of 22q11.2DS demonstrated here therefore has implications for changing attitudes about molecular genetic diagnosis that could benefit individuals with ID of currently unknown cause and their families.

A cross-sectional study of the development of volitional control of spatial attention in children with chromosome 22q11.2 deletion syndrome

Background

Chromosome 22q11.2 deletion syndrome (22q11.2DS) results from a 1.5- to 3-megabase deletion on the long arm of chromosome 22 and occurs in approximately 1 in 4000 live births. Previous studies indicate that children with 22q11.2DS are impaired on tasks involving spatial attention. However, the degree to which these impairments are due to volitionally generated (endogenous) or reflexive (exogenous) orienting of attention is unclear. Additionally, the efficacy of these component attention processes throughout child development in 22q11.2DS has yet to be examined.

Methods

Here we compared the performance of a wide age range (7 to 14 years) of children with 22q11.2DS to typically developing (TD) children on a comprehensive visual cueing paradigm to dissociate the contributions of endogenous and exogenous attentional impairments. Paired and two-sample t-tests were used to compare outcome measures within a group or between groups. Additionally, repeated measures regression models were fit to the data in order to examine effects of age on performance.

Results

We found that children with 22q11.2DS were impaired on a cueing task with an endogenous cue, but not on the same task with an exogenous cue. Additionally, it was younger children exclusively who were impaired on endogenous cueing when compared to age-matched TD children. Older children with 22q11.2DS performed comparably to age-matched TD peers on the endogenous cueing task.

Conclusions

These results suggest that endogenous but not exogenous orienting of attention is selectively impaired in children with 22q11.2DS. Additionally, the age effect on cueing in children with 22q11.2DS suggests a possible altered developmental trajectory of endogenous cueing.

Clinical applications of schizophrenia genetics: genetic diagnosis, risk, and counseling in the molecular era

Schizophrenia is a complex neuropsychiatric disease with documented clinical and genetic heterogeneity, and evidence for neurodevelopmental origins. Driven by new genetic technologies and advances in molecular medicine, there has recently been concrete progress in understanding some of the specific genetic causes of this serious psychiatric illness. In particular, several large rare structural variants have been convincingly associated with schizophrenia, in targeted studies over two decades with respect to 22q11.2 microdeletions, and more recently in large-scale, genome-wide case-control studies. These advances promise to help many families afflicted with this disease. In this review, we critically appraise recent developments in the field of schizophrenia genetics through the lens of immediate clinical applicability. Much work remains in translating the recent surge of genetic research discoveries into the clinic. The epidemiology and basic genetic parameters (such as penetrance and expression) of most genomic disorders associated with schizophrenia are not yet well characterized. To date, 22q11.2 deletion syndrome is the only established genetic subtype of schizophrenia of proven clinical relevance. We use this well-established association as a model to chart the pathway for translating emerging genetic discoveries into clinical practice. We also propose new directions for research involving general genetic risk prediction and counseling in schizophrenia.

Clues to the foundations of numerical cognitive impairments: evidence from genetic disorders

Several neurodevelopmental disorders of known genetic etiology generate phenotypes that share the characteristic of numerical and mathematical cognitive impairments. This article reviews some of the main findings that suggest a possible key role that spatial and temporal information processing impairments may play in the atypical development of numerical cognitive competence. The question of what neural substrate might underlie these impairments is also addressed, as are the challenges for interpreting neural structure/cognitive function mapping in atypically developing populations.

Chromosome 22q11.2 microdeletion syndrome

Chromosome 22q11.2 microdeletion syndrome is the most common microdeletion syndrome in humans. It involves the loss of genetic material on the short arm of one of the chromosome 22 alleles. Until advanced testing was available, this syndrome was known by various names including DiGeorge syndrome and velo-cardio-facial syndrome. This syndrome has a varied presentation with significant abnormalities including congenital heart disease, hypocalcemia, immunologic deficiencies, learning disabilities, and behavioral problems. A multidisciplinary approach is required to diagnose and manage the varied manifestations.

Cognitive, behavioural and psychiatric phenotype in 22q11.2 deletion syndrome

22q11.2 Deletion syndrome has become an important model for understanding the pathophysiology of neurodevelopmental conditions, particularly schizophrenia which develops in about 20-25% of individuals with a chromosome 22q11.2 microdeletion. From the initial discovery of the syndrome, associated developmental delays made it clear that changes in brain development were a key part of the expression. Once patients were followed through childhood into adult years, further neurobehavioural phenotypes became apparent, including a changing cognitive profile, anxiety disorders and seizure diathesis. The variability of expression is as wide as for the myriad physical features associated with the syndrome, with the addition of evolving phenotype over the developmental trajectory. Notably, variability appears unrelated to length of the associated deletion. Several mouse models of the deletion have been engineered and are beginning to reveal potential molecular mechanisms for the cognitive and behavioural phenotypes observable in animals. Both animal and human studies hold great promise for further discoveries relevant to neurodevelopment and associated cognitive, behavioural and psychiatric disorders.

Coherent motion sensitivity predicts individual differences in subtraction

Recent findings suggest deficits in coherent motion sensitivity, an index of visual dorsal stream functioning, in children with poor mathematical skills or dyscalculia, a specific learning disability in mathematics. We extended these data using a longitudinal design to unravel whether visual dorsal stream functioning is able to predict individual differences in subsequent specific mathematical skills, i.e., single-digit subtraction and multiplication. We measured children's sensitivity to coherent motion in kindergarten (mean age: 5 years 8 months) and evaluated their subtraction and multiplication skills in third grade (mean age 8 years 3 months). Findings revealed an association between subtraction but not multiplication performance and coherent motion sensitivity. This association remained significant even when intellectual ability and reading ability were additionally controlled for. Subtractions are typically solved by means of quantity-based procedural strategies, which reliably recruit the intraparietal sulcus. Against the background of a neural overlap between the intraparietal sulcus and visual dorsal stream functioning, we hypothesize that low-level visuospatial mechanisms might set constraints on the development of quantity representations, which are used during calculation, particularly in subtraction.

Copy number variants in schizophrenia: confirmation of five previous findings and new evidence for 3q29 microdeletions and VIPR2 duplications

OBJECTIVE

To evaluate previously reported associations of copy number variants (CNVs) with schizophrenia and to identify additional associations, the authors analyzed CNVs in the Molecular Genetics of Schizophrenia study (MGS) and additional available data.

METHOD

After quality control, MGS data for 3,945 subjects with schizophrenia or schizoaffective disorder and 3,611 screened comparison subjects were available for analysis of rare CNVs (<1% frequency). CNV detection thresholds were chosen that maximized concordance in 151 duplicate assays. Pointwise and genewise analyses were carried out, as well as analyses of previously reported regions. Selected regions were visually inspected and confirmed with quantitative polymerase chain reaction.

RESULTS

In analyses of MGS data combined with other available data sets, odds ratios of 7.5 or greater were observed for previously reported deletions in chromosomes 1q21.1, 15q13.3, and 22q11.21, duplications in 16p11.2, and exon-disrupting deletions in NRXN1. The most consistently supported candidate associations across data sets included a 1.6-Mb deletion in chromosome 3q29 (21 genes, TFRC to BDH1) that was previously described in a mild-moderate mental retardation syndrome, exonic duplications in the gene for vasoactive intestinal peptide receptor 2 (VIPR2), and exonic duplications in C16orf72. The case subjects had a modestly higher genome-wide number of gene-containing deletions (>100 kb and >1 Mb) but not duplications.

CONCLUSIONS

The data strongly confirm the association of schizophrenia with 1q21.1, 15q13.3, and 22q11.21 deletions, 16p11.2 duplications, and exonic NRXN1 deletions. These CNVs, as well as 3q29 deletions, are also associated with mental retardation, autism spectrum disorders, and epilepsy. Additional candidate genes and regions, including VIPR2, were identified. Study of the mechanisms underlying these associations should shed light on the pathophysiology of schizophrenia.

Behavior, brain, and genome in genomic disorders: finding the correspondences

OBJECTIVE

Within the last decade or so, there has been an acceleration of research attempting to connect specific genetic lesions to the patterns of brain structure and activation. This article comments on observations that have been made based on these recent data and discusses their importance for the field of investigations into developmental disorders.

METHODS

In making these observations, the authors focus on one specific genomic lesion, the well-studied, yet still incompletely understood, 22q11.2 deletion syndrome.

RESULTS

The authors demonstrate the degree of variability in the phenotype that occurs at both the brain and behavioral levels of genomic disorders and describe how this variability is, on close inspection, represented at the genomic level.

CONCLUSION

The authors emphasize the importance of combining genetic/genomic analyses and neuroimaging for research and for future clinical diagnostic purposes and for the purposes of developing individualized, patient-tailored treatment and remediation approaches.

Mathematical learning disabilities in special populations: phenotypic variation and cross-disorder comparisons

What is mathematical learning disability (MLD)? The reviews in this special issue adopt different approaches to defining the construct of MLD. Collectively, they demonstrate the current status of efforts to establish a consensus definition and the challenges faced in this endeavor. In this commentary, we reflect upon the proposed pathways to mathematical learning difficulties and disabilities presented across the reviews. Specifically we consider how each of the reviews contributes to identifying the MLD phenotype by specifying the range of assets and deficits in mathematics, identifying sources of individual variation, and characterizing the natural progression of MLD over the life course. We show how principled comparisons across disorders address issues about the cognitive and behavioral co-morbidities of MLD, and whether commonalities in brain dysmorphology are associated with common mathematics performance profiles. We project the status of MLD research ten years hence with respect to theoretical gains, advances in methodology, and principled intervention studies.