Association of chromosome 22q11 deletion with isolated anomalies of aortic arch laterality and branching

AbstractOBJECTIVESThe purpose of this study was to determine the frequency of chromosome 22q11 deletions in patients with isolated anomalies of the aortic arch and its branches.BACKGROUNDChromosome 22q11 deletions are often present in patients with certain forms of congenital cardiovascular disease, including tetralogy of Fallot, truncus arteriosus and interruption of the aortic arch. Among patients with these anomalies, chromosome 22q11 deletion is more common in those with abnormal aortic arch laterality or branching.METHODSWe studied 66 patients with isolated anomalies of the aortic arch and no associated intracardiac defects for deletions within chromosome 22q11, using fluorescence in situ hybridization with the cosmid probe N25 (D22S75). Arch anomalies included: double aortic arch (n = 22); right aortic arch with aberrant left subclavian artery (n = 28); right aortic arch with mirror-image branching and a vascular ring formed by a left-sided ductus from the descending aorta (n = 5); right aortic arch with mirror-image branching and no vascular ring (n = 4); and left aortic arch with aberrant right subclavian artery (n = 7). In addition, four patients had a cervical aortic arch, four had aortic coarctation and six had hypoplasia/atresia of the proximal pulmonary arteries.RESULTSChromosome 22q11 deletions were found in 16 patients (24%) across the full spectrum of anomalies studied. Among the morphologic variables analyzed, only hypoplasia/atresia of the proximal pulmonary arteries correlated with the deletion (p = 0.03). Among patients with a double arch, the frequency of chromosome 22q11 deletion was higher in those with an atretic minor arch than it was in those with a patent minor arch (p = 0.02).CONCLUSIONSChromosome 22q11 deletion is associated with isolated anomalies of laterality or branching of the aortic arch in 24% of cases in our series. These findings should alert the clinician to consider deletion screening in patients with isolated anomalies of the aortic arch

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

Typical 22q11.2 deletion syndrome appears to confer a reduced risk of schwannoma

Purpose: The LZTR1 gene has been associated with schwannomatosis tumor predisposition and is located in a region that is deleted in the great majority (89%) of patients with 22q11.2 deletion syndrome (22q11.2DS). Since it is known that approximately 1 in 500 people in the general population will develop a sporadic schwannoma and there are no reports of the occurrence of schwannoma in 22q11.2DS, we investigated whether whole-gene deletion of LZTR1 occurs in schwannomatosis and assessed the risk of schwannoma in 22q11.2DS. Methods: We assessed the genetic testing results for LZTR1-associated schwannomatosis and the clinical phenotypes of patients with 22q11.2DS. Results: There were no reports of schwannoma in over 1,500 patients with 22q11.2DS. In addition, no patients meeting clinical diagnostic criteria for schwannomatosis had a whole-gene deletion in LZTR1. Only 1 patient in 110 with an apparently sporadic vestibular schwannoma had a constitutional whole-gene deletion of LZTR1. Conclusion: People with a large 22q11.2 deletion may have a reduced risk of developing a schwannoma compared to the general population

Attention deficit hyperactivity disorder symptoms and psychosis in 22q11.2 deletion syndrome

Objective: 22q11.2 Deletion Syndrome (22q11.2DS) is associated with increased risk for schizophrenia in adulthood while ADHD is the most prevalent diagnosis in childhood. Inattention symptoms are pronounced in 22q11.2DS and given that attentional impairment is a core feature of schizophrenia, inattention symptoms may reflect underlying ADHD, psychosis, or both. We investigate whether inattention is associated with psychosis in 22q11.2DS and in other groups at risk for psychosis but without the deletion (ND) (idiopathic clinical risk and first degree family members of individuals with schizophrenia). Methods: 137 individuals with 22q11.2DS (mean age: 14.0), 84 ND individuals with subthreshold psychosis (mean age: 16.9) and 31 ND individuals with family history of psychosis (mean age: 17.0) were included in the study. Psychopathology was assessed using research diagnostic assessments. Results: ADHD total symptoms were associated with overall levels of subthreshold psychosis symptoms in 22q11.2DS (β=0.8, p=0.04). Inattention symptoms were specifically associated with positive (β=0.5, p=0.004), negative (β=0.5, p=0.03), and disorganized (β=0.5, p<0.001) symptoms, while hyperactivity-impulsivity symptoms were associated with disorganized symptoms (β=0.5, p=0.04). The prevalence of ADHD inattention symptoms was higher in 22q11.2DS with subthreshold psychosis compared to ND individuals with subthreshold psychosis (p<0.001), even when adjusting for cognitive impairment and overall psychopathology. The pattern was similar when comparing individuals with 22q11.2DS and ND individuals with family history of psychosis. Conclusions: This is the first study to examine the associations between ADHD and psychosis in 22q11.2DS. Our findings support a potentially important role of ADHD inattention symptoms in psychosis in 22q11.2DS

Disrupted anatomic networks in the 22q11.2 deletion syndrome

AbstractThe 22q11.2 deletion syndrome (22q11DS) is an uncommon genetic disorder with an increased risk of psychosis. Although the neural substrates of psychosis and schizophrenia are not well understood, aberrations in cortical networks represent intriguing potential mechanisms. Investigations of anatomic networks within 22q11DS are sparse. We investigated group differences in anatomic network structure in 48 individuals with 22q11DS and 370 typically developing controls by analyzing covariance patterns in cortical thickness among 68 regions of interest using graph theoretical models. Subjects with 22q11DS had less robust geographic organization relative to the control group, particularly in the occipital and parietal lobes. Multiple global graph theoretical statistics were decreased in 22q11DS. These results are consistent with prior studies demonstrating decreased connectivity in 22q11DS using other neuroimaging methodologies

Subthreshold psychosis in 22q11.2 deletion syndrome: multisite naturalistic study

Nearly one-third of individuals with 22q11.2 deletion syndrome (22q11.2DS) develop a psychotic disorder during life, most of them by early adulthood. Importantly, a full-blown psychotic episode is usually preceded by subthreshold symptoms. In the current study, 760 participants (aged 6-55 years) with a confirmed hemizygous 22q11.2 microdeletion have been recruited through 10 medical sites worldwide, as part of an international research consortium. Of them, 692 were nonpsychotic and with complete measurement data. Subthreshold psychotic symptoms were assessed using the Structured Interview for Prodromal Syndromes (SIPS). Nearly one-third of participants met criteria for positive subthreshold psychotic symptoms (32.8%), less than 1% qualified for acute positive subthreshold symptoms, and almost a quarter met criteria for negative/disorganized subthreshold symptoms (21.7%). Adolescents and young adults (13-25 years) showed the highest rates of subthreshold psychotic symptoms. Additionally, higher rates of anxiety disorders and attention deficit/hyperactivity disorder (ADHD) were found among the study participants with subthreshold psychotic symptoms compared to those without. Full-scale IQ, verbal IQ, and global functioning (GAF) scores were negatively associated with participants' subthreshold psychotic symptoms. This study represents the most comprehensive analysis reported to date on subthreshold psychosis in 22q11.2DS. Novel findings include age-related changes in subthreshold psychotic symptoms and evidence that cognitive deficits are associated with subthreshold psychosis in this population. Future studies should longitudinally follow these symptoms to detect whether and how early identification and treatment of these manifestations can improve long-term outcomes in those that eventually develop a psychotic disorder

Overt Cleft Palate Phenotype and TBX1 Genotype Correlations in Velo-cardio-facial/DiGeorge/22q11.2 Deletion Syndrome Patients

Velo-cardio-facial syndrome/DiGeorge syndrome, also known as 22q11.2 deletion syndrome (22q11DS) is the most common microdeletion syndrome, with an estimated incidence of 1/2,000 – 1/4,000 live births. Approximately 9–11% of patients with this disorder have an overt cleft palate (CP), but the genetic factors responsible for CP in the 22q11DS subset are unknown. The TBX1 gene, a member of the T-box transcription factor gene family, lies within the 22q11.2 region that is hemizygous in patients with 22q11DS. Inactivation of one allele of Tbx1 in the mouse does not result in CP, but inactivation of both alleles does. Based on these data, we hypothesized that DNA variants in the remaining allele of TBX1 may confer risk to CP in patients with 22q11DS. To test the hypothesis, we evaluated TBX1 exon sequencing (n = 360) and genotyping data (n = 737) with respect to presence (n = 54) or absence (n = 683) of CP in patients with 22q11DS. Two upstream SNPs (rs4819835 and rs5748410) showed individual evidence for association but they were not significant after correction for multiple testing. Associations were not identified between DNA variants and haplotypes in 22q11DS patients with CP. Overall, this study indicates that common DNA variants in TBX1 may be nominally causative for CP in patients with 22q11DS. This raises the possibility that genes elsewhere on the remaining allele of 22q11.2 or in the genome could be relevant

Nested inversion polymorphisms predispose chromosome 22q11.2 to meiotic rearrangements [RETRACTED]

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

Attention deficit hyperactivity disorder symptoms as antecedents of later psychotic outcomes in 22q11.2 deletion syndrome

Individuals with 22q11.2 Deletion Syndrome (22q11.2DS) are at substantially heightened risk for psychosis. Thus, prevention and early intervention strategies that target the antecedents of psychosis in this high-risk group are a clinical priority. Attention Deficit Hyperactivity Disorder (ADHD) is one the most prevalent psychiatric disorders in children with 22q11.2DS, particularly the inattentive subtype. The aim of this study was to test the hypothesis that ADHD inattention symptoms predict later psychotic symptoms and/or psychotic disorder in those with 22q11.2DS. 250 children and adolesents with 22q11.2DS without psychotic symptoms at baseline took part in a longitudinal study. Assessments were performed using well-validated structured diagnostic instruments at two time points (T1 (mean age=11.2, SD=3.1) and T2 (mean age=14.3, SD=3.6)). Inattention symptoms at T1 were associated with development of psychotic symptoms at T2 (OR:1.2, p=0.01) but weak associations were found with development of psychotic disorder (OR:1.2, p=0.15). ADHD diagnosis at T1 was strongly associated with development of psychotic symptoms at T2 (OR:4.5, p<0.001) and psychotic disorder (OR:5.9, p=0.02). Our findings that inattention symptoms and the diagnosis of ADHD are associated with subsequent psychotic outcomes in 22q11.2DS have important clinical implications. Future studies examining the effects of stimulant and other ADHD treatments on individuals with 22q11.2DS are warranted

Enhanced Maternal Origin of the 22q11.2 Deletion in Velocardiofacial and DiGeorge Syndromes

Velocardiofacial and DiGeorge syndromes, also known as 22q11.2 deletion syndrome (22q11DS), are congenital-anomaly disorders caused by a de novo hemizygous 22q11.2 deletion mediated by meiotic nonallelic homologous recombination events between low-copy repeats, also known as segmental duplications. Although previous studies exist, each was of small size, and it remains to be determined whether there are parent-of-origin biases for the de novo 22q11.2 deletion. To address this question, we genotyped a total of 389 DNA samples from 22q11DS-affected families. A total of 219 (56%) individuals with 22q11DS had maternal origin and 170 (44%) had paternal origin of the de novo deletion, which represents a statistically significant bias for maternal origin (p = 0.0151). Combined with many smaller, previous studies, 465 (57%) individuals had maternal origin and 345 (43%) had paternal origin, amounting to a ratio of 1.35 or a 35% increase in maternal compared to paternal origin (p = 0.000028). Among 1,892 probands with the de novo 22q11.2 deletion, the average maternal age at time of conception was 29.5, and this is similar to data for the general population in individual countries. Of interest, the female recombination rate in the 22q11.2 region was about 1.6–1.7 times greater than that for males, suggesting that for this region in the genome, enhanced meiotic recombination rates, as well as other as-of-yet undefined 22q11.2-specific features, could be responsible for the observed excess in maternal origin