Neurocognitive profiles of 22q11.2 and 16p11.2 deletions and duplications.

Rare recurrent copy number variants (CNVs) at chromosomal loci 22q11.2 and 16p11.2 are genetic disorders with lifespan risk for neuropsychiatric disorders. Microdeletions and duplications are associated with neurocognitive deficits, yet few studies compared these groups using the same measures to address confounding measurement differences. We report a prospective international collaboration applying the same computerized neurocognitive assessment, the Penn Computerized Neurocognitive Battery (CNB), administered in a multi-site study on rare genomic disorders: 22q11.2 deletions (n = 492); 22q11.2 duplications (n = 106); 16p11.2 deletion (n = 117); and 16p11.2 duplications (n = 46). Domains examined include executive functions, episodic memory, complex cognition, social cognition, and psychomotor speed. Accuracy and speed for each domain were included as dependent measures in a mixed-model repeated measures analysis. Locus (22q11.2, 16p11.2) and Copy number (deletion/duplication) were grouping factors and Measure (accuracy, speed) and neurocognitive domain were repeated measures factors, with Sex and Site as covariates. We also examined correlation with IQ. We found a significant Locus × Copy number × Domain × Measure interaction (p = 0.0004). 22q11.2 deletions were associated with greater performance accuracy deficits than 22q11.2 duplications, while 16p11.2 duplications were associated with greater specific deficits than 16p11.2 deletions. Duplications at both loci were associated with reduced speed compared to deletions. Performance profiles differed among the groups with particularly poor memory performance of the 22q11.2 deletion group while the 16p11.2 duplication group had greatest deficits in complex cognition. Average accuracy on the CNB was moderately correlated with Full Scale IQ. Deletions and duplications of 22q11.2 and 16p11.2 have differential effects on accuracy and speed of neurocognition indicating locus specificity of performance profiles. These profile differences can help inform mechanistic substrates to heterogeneity in presentation and outcome, and can only be established in large-scale international consortia using the same neurocognitive assessment. Future studies could aim to link performance profiles to clinical features and brain function.

Differential alternative splicing analysis links variation in ZRSR2 to a novel type of oral-facial-digital syndrome.

PURPOSE: Oral-facial-digital (OFD) syndromes are genetically heterogeneous developmental disorders, caused by pathogenic variants in genes involved in primary cilia formation and function. We identified a previously undescribed type of OFD with brain anomalies, ranging from alobar holoprosencephaly to pituitary anomalies, in 6 unrelated families. METHODS: Exome sequencing of affected probands was supplemented with alternative splicing analysis in patient and control lymphoblastoid and fibroblast cell lines, and primary cilia structure analysis in patient fibroblasts. RESULTS: In 1 family with 2 affected males, we identified a germline variant in the last exon of ZRSR2, NM_005089.4:c.1211_1212del NP_005080.1:p.(Gly404GlufsTer23), whereas 7 affected males from 5 unrelated families were hemizygous for the ZRSR2 variant NM_005089.4:c.1207_1208del NP_005080.1:p.(Arg403GlyfsTer24), either occurring de novo or inherited in an X-linked recessive pattern. ZRSR2, located on chromosome Xp22.2, encodes a splicing factor of the minor spliceosome complex, which recognizes minor introns, representing 0.35% of human introns. Patient samples showed significant enrichment of minor intron retention. Among differentially spliced targets are ciliopathy-related genes, such as TMEM107 and CIBAR1. Primary fibroblasts containing the NM_005089.4:c.1207_1208del ZRSR2 variant had abnormally elongated cilia, confirming an association between defective U12-type intron splicing, OFD and abnormal primary cilia formation. CONCLUSION: We introduce a novel type of OFD associated with elongated cilia and differential splicing of minor intron-containing genes due to germline variation in ZRSR2.

Rare coding variants as risk modifiers of the 22q11.2 deletion implicate postnatal cortical development in syndromic schizophrenia.

22q11.2 deletion is one of the strongest known genetic risk factors for schizophrenia. Recent whole-genome sequencing of schizophrenia cases and controls with this deletion provided an unprecedented opportunity to identify risk modifying genetic variants and investigate their contribution to the pathogenesis of schizophrenia in 22q11.2 deletion syndrome. Here, we apply a novel analytic framework that integrates gene network and phenotype data to investigate the aggregate effects of rare coding variants and identified modifier genes in this etiologically homogenous cohort (223 schizophrenia cases and 233 controls of European descent). Our analyses revealed significant additive genetic components of rare nonsynonymous variants in 110 modifier genes (adjusted P = 9.4E-04) that overall accounted for 4.6% of the variance in schizophrenia status in this cohort, of which 4.0% was independent of the common polygenic risk for schizophrenia. The modifier genes affected by rare coding variants were enriched with genes involved in synaptic function and developmental disorders. Spatiotemporal transcriptomic analyses identified an enrichment of coexpression between modifier and 22q11.2 genes in cortical brain regions from late infancy to young adulthood. Corresponding gene coexpression modules are enriched with brain-specific protein-protein interactions of SLC25A1, COMT, and PI4KA in the 22q11.2 deletion region. Overall, our study highlights the contribution of rare coding variants to the SCZ risk. They not only complement common variants in disease genetics but also pinpoint brain regions and developmental stages critical to the etiology of syndromic schizophrenia.

Prenatal vs postnatal diagnosis of 22q11.2 deletion syndrome: cardiac and noncardiac outcomes through 1 year of age.

BACKGROUND: The 22q11.2 deletion syndrome is the most common microdeletion syndrome and is frequently associated with congenital heart disease. Prenatal diagnosis of 22q11.2 deletion syndrome is increasingly offered. It is unknown whether there is a clinical benefit to prenatal detection as compared with postnatal diagnosis. OBJECTIVE: This study aimed to determine differences in perinatal and infant outcomes between patients with prenatal and postnatal diagnosis of 22q11.2 deletion syndrome. STUDY DESIGN: This was a retrospective cohort study across multiple international centers (30 sites, 4 continents) from 2006 to 2019. Participants were fetuses, neonates, or infants with a genetic diagnosis of 22q11.2 deletion syndrome by 1 year of age with or without congenital heart disease; those with prenatal diagnosis or suspicion (suggestive ultrasound findings and/or high-risk cell-free fetal DNA screen for 22q11.2 deletion syndrome with postnatal confirmation) were compared with those with postnatal diagnosis. Perinatal management, cardiac and noncardiac morbidity, and mortality by 1 year were assessed. Outcomes were adjusted for presence of critical congenital heart disease, gestational age at birth, and site. RESULTS: A total of 625 fetuses, neonates, or infants with 22q11.2 deletion syndrome (53.4% male) were included: 259 fetuses were prenatally diagnosed (156 [60.2%] were live-born) and 122 neonates were prenatally suspected with postnatal confirmation, whereas 244 infants were postnatally diagnosed. In the live-born cohort (n=522), 1-year mortality was 5.9%, which did not differ between groups but differed by the presence of critical congenital heart disease (hazard ratio, 4.18; 95% confidence interval, 1.56-11.18; P<.001) and gestational age at birth (hazard ratio, 0.78 per week; 95% confidence interval, 0.69-0.89; P<.001). Adjusting for critical congenital heart disease and gestational age at birth, the prenatal cohort was less likely to deliver at a local community hospital (5.1% vs 38.2%; odds ratio, 0.11; 95% confidence interval, 0.06-0.23; P<.001), experience neonatal cardiac decompensation (1.3% vs 5.0%; odds ratio, 0.11; 95% confidence interval, 0.03-0.49; P=.004), or have failure to thrive by 1 year (43.4% vs 50.3%; odds ratio, 0.58; 95% confidence interval, 0.36-0.91; P=.019). CONCLUSION: Prenatal detection of 22q11.2 deletion syndrome was associated with improved delivery management and less cardiac and noncardiac morbidity, but not mortality, compared with postnatal detection.

Complete Sequence of the 22q11.2 Allele in 1,053 Subjects with 22q11.2 Deletion Syndrome Reveals Modifiers of Conotruncal Heart Defects.

The 22q11.2 deletion syndrome (22q11.2DS) results from non-allelic homologous recombination between low-copy repeats termed LCR22. About 60%-70% of individuals with the typical 3 megabase (Mb) deletion from LCR22A-D have congenital heart disease, mostly of the conotruncal type (CTD), whereas others have normal cardiac anatomy. In this study, we tested whether variants in the hemizygous LCR22A-D region are associated with risk for CTDs on the basis of the sequence of the 22q11.2 region from 1,053 22q11.2DS individuals. We found a significant association (FDR p < 0.05) of the CTD subset with 62 common variants in a single linkage disequilibrium (LD) block in a 350 kb interval harboring CRKL. A total of 45 of the 62 variants were associated with increased risk for CTDs (odds ratio [OR) ranges: 1.64-4.75). Associations of four variants were replicated in a meta-analysis of three genome-wide association studies of CTDs in affected individuals without 22q11.2DS. One of the replicated variants, rs178252, is located in an open chromatin region and resides in the double-elite enhancer, GH22J020947, that is predicted to regulate CRKL (CRK-like proto-oncogene, cytoplasmic adaptor) expression. Approximately 23% of patients with nested LCR22C-D deletions have CTDs, and inactivation of Crkl in mice causes CTDs, thus implicating this gene as a modifier. Rs178252 and rs6004160 are expression quantitative trait loci (eQTLs) of CRKL. Furthermore, set-based tests identified an enhancer that is predicted to target CRKL and is significantly associated with CTD risk (GH22J020946, sequence kernal association test (SKAT) p = 7.21 × 10-5) in the 22q11.2DS cohort. These findings suggest that variance in CTD penetrance in the 22q11.2DS population can be explained in part by variants affecting CRKL expression.

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

This review aimed to update the clinical practice guidelines for managing adults with 22q11.2 deletion syndrome (22q11.2DS). The 22q11.2 Society recruited expert clinicians worldwide to revise the original clinical practice guidelines for adults in a stepwise process according to best practices: (1) a systematic literature search (1992-2021), (2) study selection and synthesis by clinical experts from 8 countries, covering 24 subspecialties, and (3) formulation of consensus recommendations based on the literature and further shaped by patient advocate survey results. Of 2441 22q11.2DS-relevant publications initially identified, 2344 received full-text review, with 2318 meeting inclusion criteria (clinical care relevance to 22q11.2DS) including 894 with potential relevance to adults. The evidence base remains limited. Thus multidisciplinary recommendations represent statements of current best practice for this evolving field, informed by the available literature. These recommendations provide guidance for the recognition, evaluation, surveillance, and management of the many emerging and chronic 22q11.2DS-associated multisystem morbidities relevant to adults. The recommendations also address key genetic counseling and psychosocial considerations for the increasing numbers of adults with this complex condition.

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 relationship between oxidative stress and psychotic disorders in 22q11.2 deletion syndrome.

BACKGROUND: 22q11.2 Deletion syndrome (22q11.2DS) is the most common microdeletion syndrome in humans. This condition is associated with a wide range of symptoms including immune and neuropsychiatric disorders. Notably, psychotic disorders including schizophrenia have a prevalence of âˆ¼ 30%. A growing body of evidence indicates that neuroinflammation and oxidative stress (OS) play a role in the pathophysiology of schizophrenia. In this study, we aim to assess the interaction between 22q11.2DS, OS and schizophrenia. METHODS: Blood samples were collected from 125 participants (including individuals with 22q11.2DS [n = 73] and healthy controls [n = 52]) from two sites: Sheba Medical Center in Israel, and University Hospital Gasthuisberg in Belgium. Baseline OS levels were evaluated by measuring Myeloperoxidase (MPO) activity. A sub-sample of the Israeli sample (n = 50) was further analyzed to examine survival of Peripheral Blood Mononuclear Cells (PBMCs) following induction of OS using vitamin K3. RESULTS: The levels of MPO were significantly higher in all individuals with 22q11.2DS, compared to healthy controls (0.346 ± 0.256 vs. 0.252 ± 0.238, p =.004). In addition, when comparing to healthy controls, the PBMCs of individuals with 22q11.2DS were less resilient to induced OS, specifically the group diagnosed with psychotic disorder (0.233 ± 0.206 for the 22q11.2DS individuals with psychotic disorders, 0.678 ± 1.162 for the 22q11.2DS individuals without psychotic disorders, and 1.428 ± 1.359 for the healthy controls, p =.003, η2 = 0.207). CONCLUSIONS: Our results suggest that dysregulation of OS mechanisms may play a role in the pathophysiology of the 22q11.2DS phenotype. The 22q11.2DS individuals with psychotic disorders were more sensitive to induction of OS, but did not present significantly different levels of OS at baseline. These results may be due to the effect of antipsychotic treatment administered to this sup-group. By elucidating novel molecular pathways, early identification of biochemical risk markers for 22q11.2DS and psychotic disorders can be detected. This can ultimately pave the way to the design of early and more precise interventions of individuals with 22q11.2DS.

Triplications of chromosome 1p36.3, including the genes GABRD and SKI, are associated with a developmental disorder and a facial gestalt.

Triplication of chromosomal region 1p36.3 is a rare genomic rearrangement. In this report, we delineate the phenotypic spectrum associated with 1p36.3 triplications. We describe four patients with microtriplications of variable size, but with a strong phenotypic overlap, and compare them to previously described patients with an isolated triplication or duplication of this region. The 1p36.3 triplication syndrome is associated with a distinct phenotype, characterized by global developmental delay, moderate intellectual disability, seizures, behavioral problems, and specific facial dysmorphic features, including ptosis, hypertelorism, and arched eyebrows. The de novo occurrence of these microtriplications demonstrates the reduced reproductive fitness associated with this genotype, in contrast to 1p36.3 duplications which are mostly inherited and can be associated with similar facial features but with a less severe developmental phenotype. The shared triplicated region encompasses four disease-related genes of which GABRD and SKI are most likely to contribute to the phenotype.

Neurodevelopmental profile and stages of regression in Phelan-McDermid syndrome.

AIM: To characterize the neurodevelopmental profile of patients with Phelan-McDermid syndrome (PMS) and describe the nature and trajectory of regression. METHOD: This was a retrospective, monocentric study examining the clinical and developmental data of 24 patients (average age = 25 years 6 months, range = 6-56 years, n = 13 males) with a confirmed 22q13.3 terminal deletion carried out at the Centre for Human Genetics, University Hospital Leuven. The neurodevelopmental profile of individuals with PMS was examined, combining both cross-sectional and longitudinal data obtained by systematic review of digital medical records. RESULTS: Remarkable loss of skills was present in 19 individuals affecting both language and motor skills. The first manifestations of neurodevelopmental regression occurred, on average, at the age of 7 years 6 months (range = 5-11 years). Language skills (active vocabulary) were primarily affected followed by, in order of loss, psychosocial adaptability, fine motor skills, and walking ability. The course of regression was characterized by a distinctive four-stage pattern. The first stage often occurred around mid-childhood and was defined by a pronounced and abrupt decline of language skills. This stage was generally followed by the second stage where a (prolonged) period of stagnation of regression was seen. The third stage was defined by acute neuropsychiatric decline (e.g. catatonia, hallucinations, psychosis). Acute events such as severe sickness, hormonal shifts, and psychosocial stress frequently preceded the fourth and final stage, which was characterized by severe neuromotor degeneration. INTERPRETATION: Neurodevelopmental regression should be considered as a key feature of PMS. We present a four-stage model of neurodevelopmental regression, entailing language skills, fine and gross motor function, and psychosocial adaptation, which can be applied in future practice and research.

The 22q11 low copy repeats are characterized by unprecedented size and structural variability.

Low copy repeats (LCRs) are recognized as a significant source of genomic instability, driving genome variability and evolution. The Chromosome 22 LCRs (LCR22s) mediate nonallelic homologous recombination (NAHR) leading to the 22q11 deletion syndrome (22q11DS). However, LCR22s are among the most complex regions in the genome, and their structure remains unresolved. The difficulty in generating accurate maps of LCR22s has also hindered localization of the deletion end points in 22q11DS patients. Using fiber FISH and Bionano optical mapping, we assembled LCR22 alleles in 187 cell lines. Our analysis uncovered an unprecedented level of variation in LCR22s, including LCR22A alleles ranging in size from 250 to 2000 kb. Further, the incidence of various LCR22 alleles varied within different populations. Additionally, the analysis of LCR22s in 22q11DS patients and their parents enabled further refinement of the rearrangement site within LCR22A and -D, which flank the 22q11 deletion. The NAHR site was localized to a 160-kb paralog shared between the LCR22A and -D in seven 22q11DS patients. Thus, we present the most comprehensive map of LCR22 variation to date. This will greatly facilitate the investigation of the role of LCR variation as a driver of 22q11 rearrangements and the phenotypic variability among 22q11DS patients.

Genetic contributors to risk of schizophrenia in the presence of a 22q11.2 deletion.

Schizophrenia occurs in about one in four individuals with 22q11.2 deletion syndrome (22q11.2DS). The aim of this International Brain and Behavior 22q11.2DS Consortium (IBBC) study was to identify genetic factors that contribute to schizophrenia, in addition to the ~20-fold increased risk conveyed by the 22q11.2 deletion. Using whole-genome sequencing data from 519 unrelated individuals with 22q11.2DS, we conducted genome-wide comparisons of common and rare variants between those with schizophrenia and those with no psychotic disorder at age ≥25 years. Available microarray data enabled direct comparison of polygenic risk for schizophrenia between 22q11.2DS and independent population samples with no 22q11.2 deletion, with and without schizophrenia (total n = 35,182). Polygenic risk for schizophrenia within 22q11.2DS was significantly greater for those with schizophrenia (padj = 6.73 × 10-6). Novel reciprocal case-control comparisons between the 22q11.2DS and population-based cohorts showed that polygenic risk score was significantly greater in individuals with psychotic illness, regardless of the presence of the 22q11.2 deletion. Within the 22q11.2DS cohort, results of gene-set analyses showed some support for rare variants affecting synaptic genes. No common or rare variants within the 22q11.2 deletion region were significantly associated with schizophrenia. These findings suggest that in addition to the deletion conferring a greatly increased risk to schizophrenia, the risk is higher when the 22q11.2 deletion and common polygenic risk factors that contribute to schizophrenia in the general population are both present.

Cross-sectional and longitudinal findings in patients with proximal 22q11.2 duplication: A retrospective chart study.

Duplications on Chromosome 22q11.2 (22q11.2 dup) are associated with a wide spectrum of physical and neurodevelopmental features. In this chart review, physical, developmental, and behavioral features of 28 patients with 22q11.2 dup (median age = 17.11 years) are reported, and phenotypes of de novo and inherited duplications are compared. Common medical anomalies include nutritional problems (57%), failure to thrive (33%), transient hearing impairment (52%), and congenital heart defects (33%). Developmental, speech-language, and motor delay are common in infancy, while attention (64%), learning (60%), and motor problems (52%) are typically reported at primary school age. Attention-deficit/hyperactivity disorders are diagnosed in 44%. Median full-scale intelligence quotient is in the borderline range (IQ 76), with one-fifth of patients having mild intellectual disability. Longitudinal data in 11 patients, with the first assessment at a median age of 5.2 years and the second assessment at a median age of 8.8 years, indicate that almost two-third of patients have a relative stable cognitive trajectory, whereas one-third show a growing into deficit profile. In patients with de novo duplications, there is a trend of more failure to thrive, while more patients with inherited duplications follow special education.

Resilience and quality of life in young adults with a 22q11.2 deletion syndrome: a patient's perspective.

In the transition period between adolescence and young adulthood, individuals with 22q11.2DS are at an increased risk of developing severe psychiatric disorders. Various studies have focused on detecting risk factors, but until now protective factors are still understudied in 22q11.2DS. The current case-control study focuses on the role of resilience and quality of life (QoL) in young adults with 22q11.2DS and behavioural problems, in comparison with persons with an intellectual disability (ID) without a known genetic disorder. Self-report (and caregiver report) standardized questionnaires were used. Predictive general linear models were constructed to compare the resilience and quality of life across both groups (22q11.2DS vs ID-group) and to analyse the association between personal characteristics in both groups. Young adults with a 22q11.2DS show less resilience compared with both the general population norms and young adults with ID. Only a subscale of resilience (Acceptance of self and life) contributes to the reported level of QoL. Reported health problems are not related to resilience, but have an important effect on QoL. Our results suggest different factors are underlying resilience and the relation with QoL in 22q11.2DS and ID in general. These factors deserve more research and are important to take into account in clinical practice.

Atypical chromosome 22q11.2 deletions are complex rearrangements and have different mechanistic origins.

The majority (99%) of individuals with 22q11.2 deletion syndrome (22q11.2DS) have a deletion that is caused by non-allelic homologous recombination between two of four low copy repeat clusters on chromosome 22q11.2 (LCR22s). However, in a small subset of patients, atypical deletions are observed with at least one deletion breakpoint within unique sequence between the LCR22s. The position of the chromosome breakpoints and the mechanisms driving those atypical deletions remain poorly studied. Our large-scale, whole genome sequencing study of >1500 subjects with 22q11.2DS identified six unrelated individuals with atypical deletions of different types. Using a combination of whole genome sequencing data and fiber-fluorescence in situ hybridization, we mapped the rearranged alleles in these subjects. In four of them, the distal breakpoints mapped within one of the LCR22s and we found that the deletions likely occurred by replication-based mechanisms. Interestingly, in two of them, an inversion probably preceded inter-chromosomal 'allelic' homologous recombination between differently oriented LCR22-D alleles. Inversion associated allelic homologous recombination (AHR) may well be a common mechanism driving (atypical) deletions on 22q11.2.

Stressed parents, happy parents. An assessment of parenting stress and family quality of life in families with a child with Phelan-McDermid syndrome.

BACKGROUND: Individuals with Phelan-McDermid syndrome (PMS) are characterised by phenotypical traits that can be experienced as challenging by their environment. This study assessed parenting stress and Family Quality of Life (FQOL) in parents of individuals with PMS and identified potential contributing variables. METHOD: Mothers (n = 14) and fathers (n = 13) of individuals with PMS (n = 14; 6 females, 8 males; age 2-37, M = 20, SD = 11.92) completed questionnaires on parenting stress, FQOL, adaptive behaviour and background characteristics. RESULTS: Mothers and fathers experienced high, similar and related levels of parenting stress and FQOL satisfaction. Parenting stress and FQOL satisfaction were inversely related. High and low ratings were retrieved for subscales measuring feelings of parental role restriction and emotional well-being, respectively. The adaptive skills of the individuals with PMS were related to fathers' parenting stress and FQOL satisfaction. CONCLUSIONS: Clinical practice is encouraged to be attentive to family dynamics and grasp opportunities to interact with these dynamics.

Deletion size analysis of 1680 22q11.2DS subjects identifies a new recombination hotspot on chromosome 22q11.2.

Recurrent, de novo, meiotic non-allelic homologous recombination events between low copy repeats, termed LCR22s, leads to the 22q11.2 deletion syndrome (22q11.2DS; velo-cardio-facial syndrome/DiGeorge syndrome). Although most 22q11.2DS patients have a similar sized 3 million base pair (Mb), LCR22A-D deletion, some have nested LCR22A-B or LCR22A-C deletions. Our goal is to identify additional recurrent 22q11.2 deletions associated with 22q11.2DS, serving as recombination hotspots for meiotic chromosomal rearrangements. Here, using data from Affymetrix 6.0 microarrays on 1680 22q11.2DS subjects, we identified what appeared to be a nested proximal 22q11.2 deletion in 38 (2.3%) of them. Using molecular and haplotype analyses from 14 subjects and their parent(s) with available DNA, we found essentially three types of scenarios to explain this observation. In eight subjects, the proximal breakpoints occurred in a small sized 12 kb LCR distal to LCR22A, referred to LCR22A+, resulting in LCR22A+-B or LCR22A+-D deletions. Six of these eight subjects had a nested 22q11.2 deletion that occurred during meiosis in a parent carrying a benign 0.2 Mb duplication of the LCR22A-LCR22A+ region with a breakpoint in LCR22A+. Another six had a typical de novo LCR22A-D deletion on one allele and inherited the LCR22A-A+ duplication from the other parent thus appearing on microarrays to have a nested deletion. LCR22A+ maps to an evolutionary breakpoint between mice and humans and appears to serve as a local hotspot for chromosome rearrangements on 22q11.2.

Nested Inversion Polymorphisms Predispose Chromosome 22q11.2 to Meiotic Rearrangements.

Inversion polymorphisms between low-copy repeats (LCRs) might predispose chromosomes to meiotic non-allelic homologous recombination (NAHR) events and thus lead to genomic disorders. However, for the 22q11.2 deletion syndrome (22q11.2DS), the most common genomic disorder, no such inversions have been uncovered as of yet. Using fiber-FISH, we demonstrate that parents transmitting the de novo 3 Mb LCR22A-D 22q11.2 deletion, the reciprocal duplication, and the smaller 1.5 Mb LCR22A-B 22q11.2 deletion carry inversions of LCR22B-D or LCR22C-D. Hence, the inversions predispose chromosome 22q11.2 to meiotic rearrangements and increase the individual risk for transmitting rearrangements. Interestingly, the inversions are nested or flanking rather than coinciding with the deletion or duplication sizes. This finding raises the possibility that inversions are a prerequisite not only for 22q11.2 rearrangements but also for all NAHR-mediated genomic disorders.

Low prevalence of substance use in people with 22q11.2 deletion syndrome.

BACKGROUND: 22q11.2 deletion syndrome (22q11DS), one of the most common recurrent copy number variant disorders, is associated with dopaminergic abnormalities and increased risk for psychotic disorders. AIMS: Given the elevated prevalence of substance use and dopaminergic abnormalities in non-deleted patients with psychosis, we investigated the prevalence of substance use in 22q11DS, compared with that in non-deleted patients with psychosis and matched healthy controls. METHOD: This cross-sectional study involved 434 patients with 22q11DS, 265 non-deleted patients with psychosis and 134 healthy controls. Psychiatric diagnosis, full-scale IQ and COMT Val158Met genotype were determined in the 22q11DS group. Substance use data were collected according to the Composite International Diagnostic Interview. RESULTS: The prevalence of total substance use (36.9%) and substance use disorders (1.2%), and weekly amounts of alcohol and nicotine use, in patients with 22q11DS was significantly lower than in non-deleted patients with psychosis or controls. Compared with patients with 22q11DS, healthy controls were 20 times more likely to use substances in general (P < 0.001); results were also significant for alcohol and nicotine use separately. Within the 22q11DS group, there was no relationship between the prevalence of substance use and psychosis or COMT genotype. Male patients with 22q11DS were more likely to use substances than female patients with 22q11DS. CONCLUSIONS: The results suggest that patients with 22q11DS are at decreased risk for substance use and substance use disorders despite the increased risk of psychotic disorders. Further research into neurobiological and environmental factors involved in substance use in 22q11DS is necessary to elucidate the mechanisms involved. DECLARATION OF INTEREST: None.

Vestibular dysfunction is a manifestation of 22q11.2 deletion syndrome.

The 22q11.2 deletion syndrome (22q11.2DS) is the second most common cause of developmental delay after Down syndrome. Impaired cognitive development is highly prevalent, but also motor abnormalities such as hypotonia and delays in achieving motor milestones are described. Instability is frequently detected in children, adolescents, and adults and is mostly attributed to their limited motor performance. Until now, vestibular function has not been investigated in these patients, despite the growing evidence that they often have inner ear malformations. The aim of this prospective study was to identify the presence and character of vestibular dysfunction in 22q11.2DS. We investigated 23 subjects with proven 22q11.2DS, older than the age of 12. We performed caloric testing and pendular rotation chair tests with videonystagmography, cervical vestibular-evoked myogenic potential (c-VEMP)-testing, and posturography. Additional otoscopy and audiometry were performed on all subjects. We found a unilateral caloric hypofunction in 55% of patients, a certain absent c-VEMP response in 15% of ears, an inconclusive c-VEMP response in 33% of ears, and abnormal posturography in 68% of patients, of whom 42% displayed a typical vestibular pattern. Remarkably, 90% revealed uni- or bilateral weak caloric responses, independent of caloric symmetry. Vestibular dysfunction is frequent in subjects with 22q11.2DS. This knowledge should be taken into account when assessing motor performance in these patients. Additional larger studies are needed to determine whether this dysfunction implicates a therapeutic potential.