Preliminary structure and predictive value of attenuated negative symptoms in 22q11.2 deletion syndrome.

Current research in schizophrenia suggests that negative symptoms cannot be considered a unitary construct and should be divided in two dimensions: lack of motivation and impoverishment of expression. In addition, negative symptoms are particularly related to decreased daily-life functioning. In the present study, we aimed to replicate these results in a sample of participants with 22q11.2 deletion syndrome (22q11DS), a neurogenetic condition associated with high risk of developing schizophrenia. We also expected to observe an association between the COMT Val/Met polymorphism and negative symptoms. We examined the factorial structure of negative symptoms in a sample of 47 individuals with 22q11DS using the Structured Interview for Prodromal Symptoms (SIPS) and the Positive and Negative Syndrome Scale (PANSS). We also performed stepwise regression analyses to investigate the associations between negative symptoms, adaptive skills and the COMT Val/Met polymorphism. Negative symptoms were explained by a two-factor solution, namely the "amotivation and social withdrawal" and the "emotional withdrawal and expression" dimensions. The motivational dimension was significantly associated with daily-life functioning. Met carriers were rated as experiencing significantly more symptoms of amotivation. The results are interpreted in the light of existing cognitive models in the field of motivation and schizophrenia.

A case of SUDEP in a patient with Dravet syndrome with SCN1A mutation.

A boy with a clinical history of pharmacologically resistant Dravet syndrome died suddenly after falling asleep. The autopsy concluded that the cause of death was sudden unexpected death in epilepsy (SUDEP). Postmortem molecular analysis of the SCN1A gene by multiplex ligation-dependent probe amplification (MLPA), high-resolution melting curve analysis (HRMCA), and sequencing revealed a frameshift duplication of adenosine at position 504. The incidence of this mutation is discussed as a potential cause of SUDEP.

Abnormal cortical activation during response inhibition in 22q11.2 deletion syndrome.

22q11.2 deletion syndrome (22q11.2DS) is a well-known genetic risk factor for schizophrenia. The catechol-O-methyltransferase (COMT) gene falls within the 22q11.2 minimal critical region of the deletion. Brain activity, as measured by functional magnetic resonance imaging (fMRI) during a Go/NoGo, response inhibition task was assessed in adolescents with 22q11.2DS (n = 13), typically developing (TD) controls (n = 14), and controls with developmental disability (DD, n = 9). Subjects with 22q11.2DS were also genotyped for the COMT Met/Val polymorphism. Groups did not differ on task performance. However, compared to both control groups, the 22q11.2DS group showed greater brain activation within left parietal regions. Comparison of brain activation between 22q11.2DS Met and Val subgroups revealed significantly increased activation (Met>Val) in the cingulate but not the dorsolateral prefrontal cortex. These preliminary findings suggest that adolescents with 22q11.2DS compensate for executive dysfunction via recruitment of parietal regions. Further, the COMT Met subgroup of 22q11.2DS may recruit additional cingulate activation for tasks requiring attention and inhibition. 22q11.2DS is a unique model for learning about the deleterious effects of decreased dosage of the COMT gene on brain function.

Prenatal diagnostic indicators of paternal uniparental disomy 14.

OBJECTIVES: To present clinical findings of a child with paternal uniparental isodisomy 14 (pat UPD14) focusing on relevant prenatal characteristics. METHODS/RESULTS: Ultrasonography at 23 weeks of gestation of a 37-year-old multigravid woman revealed a fetus with polyhydramnios, small thorax, and short, distinctively angled ribs. Fetal karyotype was 46,XY. The child was born spontaneously at 35 weeks with poor neonatal adaptation. From birth, he presented with severe respiratory insufficiency due to severe thoracic malformation. Clinical examination revealed a small, bell-shaped thorax, redundant lax skin, mild contractures of the fingers and dysmorphic facial features. Chest X rays showed short, abnormally curved ribs that suggested the possibility of pat UPD14, which was confirmed by molecular analysis. CONCLUSION: Pat UPD14 is associated with a distinct clinical phenotype. Prognosis is poor because of severe respiratory insufficiency and neurodevelopmental retardation. Our report confirms salient postnatal signs of previous descriptions, especially the characteristic radiological abnormalities with ribs showing a 'coat-hanger' configuration. Retrospective fetal ultrasound of our case allowed the identification of this pathognomonic feature prenatally, which makes it possible to consider pat UPD14 at routine prenatal sonography, in particular in combination with a small bell-shaped thorax and polyhydramnios.

No evidence for an effect of COMT Val158Met genotype on executive function in patients with 22q11 deletion syndrome.

OBJECTIVE: Previous studies linking the catechol O-methyltransferase (COMT) functional polymorphism to the specific phenotype in 22q11.2 deletion syndrome (22q11.2DS) have yielded inconsistent results. The goal of the present study was to replicate a recent finding that executive function is higher in individuals hemizygous for the Met allele. METHOD: Thirty-four children and young adults with a 22q11.2 microdeletion, hemizygous for the Val (N=14) or Met (N=20) polymorphism, were tested on measures of executive function, IQ, and memory. RESULTS: No significant differences were detected between Met- and Val-hemizygous participants on measures of executive function. The groups did not differ on full-scale, performance, and verbal IQ or on verbal and visual memory. CONCLUSIONS: These results suggest either a small effect of the COMT polymorphism on executive function in 22q11.2DS or no effect at all. Further research is needed to characterize the implications of hemizygosity of COMT in 22q11.2DS for cognitive function.

COMT genotype predicts longitudinal cognitive decline and psychosis in 22q11.2 deletion syndrome.

Although schizophrenia is strongly hereditary, there are limited data regarding biological risk factors and pathophysiological processes. In this longitudinal study of adolescents with 22q11.2 deletion syndrome, we identified the catechol-O-methyltransferase low-activity allele (COMT(L)) as a risk factor for decline in prefrontal cortical volume and cognition, as well as for the consequent development of psychotic symptoms during adolescence. The 22q11.2 deletion syndrome is a promising model for identifying biomarkers related to the development of schizophrenia.

A t(2;8) balanced translocation with breakpoints near the human HOXD complex causes mesomelic dysplasia and vertebral defects.

Mesomelic dysplasia is a severe shortening of forearms and forelegs, and is found in several distinct human syndromes. Here, we report the cloning of the breakpoints of a human t(2;8)(q31;p21) balanced translocation associated with mesomelic dysplasia of the upper limbs, as well as with vertebral defects. We show that this translocation does not disrupt any gene, hence it most likely exerts its deleterious effect by modifying gene regulation. The HOXD complex lies approximately 60 kb from the translocation breakpoint on chromosome 2. This cluster of genes has an important role in the development of both the vertebral column and the limbs. Only a few cases of mutations of these homeotic genes have been described so far in humans. However, gain- and loss-of-function of Hoxd genes in mice can induce mesomelic dysplasia-like phenotypes, suggesting that misexpression of HOXD genes may indeed be at the origin of this hereditary phenotype.