Temporal lobe anatomy and psychiatric symptoms in velocardiofacial syndrome (22q11.2 deletion syndrome)

Impaired activation of face processing networks revealed by functional magnetic resonance imaging in 22q11.2 deletion syndrome

BACKGROUND

22q11.2 deletion syndrome (22q11DS) is a neurogenetic syndrome associated with a high rate of psychiatric disorders. Previous research has revealed distinctive cognitive deficits, including impaired face processing. However, the neuro-functional substrates underlying these deficits have not been explored. Our aim was to investigate facial and emotional processing in 22q11DS.

METHODS

During event-related functional magnetic resonance imaging, 15 individuals with 22q11DS were compared with age- and gender-matched healthy control subjects on a simple visual categorization task (faces or houses). Each stimulus was presented twice, and faces had either neutral or emotional (fearful) expressions.

RESULTS

Abnormal responses to faces were observed in 22q11DS, including a lack of normal face-selectivity in fusiform gyrus. By contrast, responses to houses were comparable across groups, with preserved selectivity in parahippocampal gyrus. Results also revealed a repetition-suppression effect for fearful faces in the right amygdala, which arose in healthy control subjects only, suggesting a lack of amygdala modulation by fear expression in 22q11DS.

CONCLUSIONS

Our results demonstrate selective anomalies in several brain regions critically implicated in visual and social function in 22q11DS. These findings suggest important new avenues for studying emotional processing and social deficits frequently observed in psychotic patients and establishing their relation to specific phenotypic manifestations in 22q11DS.

Velo-cardio-facial syndrome: 30 Years of study

Velo-cardio-facial syndrome is one of the names that has been attached to one of the most common multiple anomaly syndromes in humans. The labels DiGeorge sequence, 22q11 deletion syndrome, conotruncal anomalies face syndrome, CATCH 22, and Sedlacková syndrome have all been attached to the same disorder. Velo-cardio-facial syndrome has an expansive phenotype with more than 180 clinical features described that involve essentially every organ and system. The syndrome has drawn considerable attention because a number of common psychiatric illnesses are phenotypic features including attention deficit disorder, schizophrenia, and bipolar disorder. The expression is highly variable with some individuals being essentially normal at the mildest end of the spectrum, and the most severe cases having life-threatening and life-impairing problems. The syndrome is caused by a microdeletion from chromosome 22 at the q11.2 band. Although the large majority of affected individuals have identical 3 megabase deletions, less than 10% of cases have smaller deletions of 1.5 or 2.0 megabases. The 3 megabase deletion encompasses a region containing 40 genes. The syndrome has a population prevalence of approximately 1:2,000 in the United States, although incidence is higher. Although initially a clinical diagnosis, today velo-cardio-facial syndrome can be diagnosed with extremely high accuracy by fluorescence in situ hybridization and several other laboratory techniques. Clinical management is age dependent with acute medical problems such as congenital heart disease, immune disorders, feeding problems, cleft palate, and developmental disorders occupying management in infancy and preschool years. Management shifts to cognitive, behavioral, and learning disorders during school years, and then to the potential for psychiatric disorders including psychosis in late adolescence and adult years. Although the majority of people with velo-cardio-facial syndrome do not develop psychosis, the risk for severe psychiatric illness is 25 times higher for people affected with velo-cardio-facial syndrome than that of the general population. Therefore, interest in understanding the nature of psychiatric illness in the syndrome remains strong.

Developmental trajectories of brain structure in adolescents with 22q11.2 deletion syndrome: a longitudinal study

The 22q11.2 deletion syndrome (22q11.2DS) is associated with very high rates of schizophrenia-like psychosis and cognitive deficits. Here we report the results of the first longitudinal study assessing brain development in individuals with 22q11.2DS. Twenty-nine children with 22q11.2DS and 29 age and gender matched controls were first assessed during childhood or early adolescence; Nineteen subjects with 22q11.2DS and 18 controls underwent follow-up during late adolescence-early adulthood. The 22q11.2DS subjects showed greater longitudinal increase in cranial and cerebellar white matter, superior temporal gyrus, and caudate nucleus volumes. They also had a more robust decrease in amygdala volume. Verbal IQ (VIQ) scores of the 22q11.2DS group that developed psychotic disorders declined significantly between assessments. Decline in VIQ in 22q11.2DS was associated with more robust reduction of left cortical grey matter volume. No volumetric differences were detected between psychotic and nonpsychotic subjects with 22q11.2DS. Brain maturation associated with verbal cognitive development in 22q11.2DS varies from that observed in healthy controls. Further longitudinal studies are likely to elucidate brain developmental trajectories in 22q11.2DS and their association to psychotic disorders and cognitive deficits in this population.

Hippocampal volume reduction in children with chromosome 22q11.2 deletion syndrome is associated with cognitive impairment

Background

Previous investigations of individuals with chromosome 22q11.2 deletion syndrome (DS22q11.2) have reported alterations in both brain anatomy and cognitive function. Neuroanatomical studies have reported multiple abnormalities including changes in both gray and white matter in the temporal lobe, including the amygdala and hippocampus. Separate investigations of cognitive abilities have established the prevalence of general intellectual impairment, although the actual extent to which a single individual is affected varies greatly within the population. The present study was designed to examine structures within the temporal lobe and assess their functional significance in terms of cognition in children with DS22q11.2.

Method

A total of 72 children (ages 7–14 years) participated in the investigation: 36 children (19 female, 17 male) tested FISH positive for chromosome 22q11.2 deletion (Mean age = 10 years 9 months, ± 2 yr 4 mo) and 36 were age-matched typically developing controls (13 female, 23 male; Mean age = 10 years 6 months, ± 1 yr 11 mo). For each subject, a three-dimensional high-resolution (1 mm isotropic) T1-weighted structural MRI was acquired. Neuroanatomical guidelines were used to define borders of the amygdala and hippocampus bilaterally and volumes were calculated based on manual tracings of the regions. The Wechsler Intelligence Scale for Children (WISC) was also administered.

Results

Volumetric reductions in total gray matter, white matter, and both the amygdala and hippocampus bilaterally were observed in children with DS22q11.2. Reductions in the left hippocampus were disproportionate to decreases in gray matter after statistically controlling for group differences in total gray matter, age, and data collection site. This specific reduction in hippocampal volume was significantly correlated with performance on standardized measures of intelligence, whereas the other neuroanatomical measures were not (gray/white matter, CSF, and amygdala).

Conclusion

Results from this study not only contribute to the understanding of the neuroanatomical variation in DS22q11.2, but also provide insight into the nature and source of the cognitive impairments associated with the syndrome. Specifically, we report that decreases in hippocampal volume may serve as an index of severity for cognitive impairments in children with DS22q11.2.

From genes to brain: understanding brain development in neurogenetic disorders using neuroimaging techniques

For almost two decades, a considerable amount of work has been devoted to the accurate delineation of normal and abnormal brain development using cerebral MRI. In the broad field of neuroimaging research, specific genetic conditions associated with impaired cognitive performances or with psychiatric symptoms have received increased attention because of their potential for revealing insight on the biologic correlates of behavior. First delineated by volumetric measurements of cerebral lobes or regions of interest, new image processing techniques are currently defining cerebral phenotypes associated with neurogenetic disorders with increasing precision. In this article the authors review the contribution of structural brain imaging in advancing our understanding of the pathogenic processes underlying altered brain development in Down, fragile X, and velocardiofacial (22q11DS) syndromes.

Autistic Spectrum Disorders in Velo-cardio Facial Syndrome (22q11.2 Deletion)

The extent to which the phenotype of children comorbid for velocardiofacial syndrome (VCFS) and autism spectrum disorders (ASD) differs from that of VCFS-only has not been studied. The sample consisted of 41 children (20 females) with VCFS, ranging in age from 6.5 years to 15.8 years. Eight children with VCFS met formal DSM-IV diagnostic criteria for autism based upon the ADI-R. These eight plus an additional nine participants met diagnostic criteria for an autistic spectrum disorder (VCFS + ASD). Ninety-four percent of the children with VCFS + ASD had a co-occurring psychiatric disorder while 60% of children with VCFS had a psychiatric disorder. Children with VCFS + ASD had larger right amygdala volumes. All other neuroanatomic regions of interest were statistically similar between the two groups.

A gender-moderated effect of a functional COMT polymorphism on prefrontal brain morphology and function in velo-cardio-facial syndrome (22q11.2 deletion syndrome)

Caused by a microdeletion at the q11.2 locus of chromosome 22, velo-cardio-facial syndrome (also known as VCFS, 22q11 deletion syndrome, DiGeorge sequence, and conotruncal anomalies face syndrome) is associated with a distinctive physical, neurocognitive, and psychiatric phenotype. Increasing interest has centered on identifying the candidate genes within the deleted region that may contribute to this phenotype. One attractive candidate gene is catechol-O-methyltransferase (COMT) because it encodes for a protein that degrades dopamine. Variability in COMT activity is related to a Val158Met polymorphism that has been implicated in prefrontal lobe cognitive and neuropsychiatric function. We examined the effect of this polymorphism on prefrontal anatomy and frontally-mediated neuropsychological function in 58 children with VCFS, 26 who were hemizygous for the Met allele and 32 for the Val allele. We found an allele by gender interaction effect on the volumes of the dorsal prefrontal and orbital prefrontal cortices. We did not find significant allele or gender by allele effects on neuropsychological tasks, although girls with the Met allele tended to perform better on the Wisconsin card sorting task. These data suggest that this functional COMT polymorphism may play a gender-moderated role in determining the neuroanatomic phenotype of individuals with VCFS. Longitudinal evaluation of these children is essential in order to identify potential clinical implications of this allele by gender interaction.