22q11 deletion syndrome: a genetic subtype of schizophrenia

Bassett, Anne S.; Chow, Eva W.C.

doi:10.1016/s0006-3223(99)00114-6

Cited by 296 publications

(264 citation statements)

References 98 publications

(124 reference statements)

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“…12,13,19,20,[60][61][62] They are especially interesting as the same regions may encompass susceptibility genes for schizophrenia. [63][64][65][66][67][68][69][70] Park et al 71 made similar conclusions in a study of psychotic BD in which most areas of linkage overlapped with those reported in previous investigations of schizophrenia.…”

Section: Psychotic Symptoms In Bdsupporting

confidence: 71%

The phenotypes of bipolar disorder: relevance for genetic investigations

2005

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The search for susceptibility genes for bipolar disorder (BD) depends on appropriate definitions of the phenotype. In this paper, we review data on diagnosis and clinical features of BD that could be used in genetic studies to better characterize patients or to define homogeneous subgroups. Clinical symptoms, long-term course, comorbid conditions, and response to prophylactic treatment may define groups associated with more or less specific loci. One such group is characterized by symptoms of psychosis and linkage to 13q and 22q. A second group includes mainly bipolar II patients with comorbid panic disorder, rapid mood switching, and evidence of chromosome 18 linkage. A third group comprises typical BD with an episodic course and favourable response to lithium prophylaxis. Reproducibility of cognitive deficits across studies raises the possibility of using cognitive profiles as endophenotypes of BD, with deficits in verbal explicit memory and executive function commonly reported. Brain imaging provides a more ambiguous data set consistent with heterogeneity of the illness. Keywords: bipolar disorder; genetics; endophenotype; neurocognitive function; brain imaging Bipolar disorder (BD) has a genetic basis with heritability of at least 80%. 1 A number of studies have attempted to map the susceptibility loci giving evidence of linkage in multiple genomic regions. In particular, findings in 4p, 4q, 8q, 10p, 12q24, 13q, 18p, 18q, 21q, and 22q have been supported by more than one study. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] However, these studies have not identified any specific genes, and a recent metaanalysis of available genome scans showed no regions with a conclusive evidence of linkage. 20 The relatively slow progress of gene-mapping efforts is often explained by the 'complex' nature of the illness and of the genotype-phenotype relation. The complexity most likely includes heterogeneity, interactions of multiple loci, incomplete penetrance, as well as phenotypes resulting from environmental effects-either alone or in interaction with the genetic predisposition. The goal of psychiatric genetic research is identification of (heritable) variations in DNA sequence or function that influence behaviour or give rise to mental illness. By definition, in complex (multifactorial) traits, this link is not unique and specific. That is, a particular change in gene sequence does not necessarily lead to a specific behaviour, and similar behaviours (symptoms) may be due to distinct (sets of) genes. Moreover, we must consider the possibility that the path between the genotype and behaviour is not unidirectional. Emerging examples point not only to general effects of environment, for instance stress, on behaviour, but also to specific behaviours influencing gene function that can be transmitted onto the next generation. 21 No single method is considered clearly superior in identifying susceptibility genes for complex traits such as BD. Most researchers agree that a combination of strategies is most lik...

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Section: Psychotic Symptoms In Bdsupporting

confidence: 71%

The phenotypes of bipolar disorder: relevance for genetic investigations

2005

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“…Classically associated features include mild facial dysmorphic features, learning difficulties, hypernasal speech, and congenital anomalies such as congenital heart defects and velopharyngeal insufficiency and/or submucous cleft palate [3]. Overt cleft palate is rare in 22qDS [2••].…”

Section: Common Features and Prevalence Of 22qdsmentioning

confidence: 99%

“…Thus, many studies of schizophrenia would have inclusion and exclusion criteria and sampling strategies that would bias against ascertainment of individuals with 22qDS. However, high rates of 22qDS result from screening for patients with physical features of the syndrome and/or borderline to mild mental retardation [3] or childhood-onset schizophrenia (Table 1).…”

Section: How Common Is 22qds In Schizophrenia?mentioning

confidence: 99%

Schizophrenia and 22q11.2 deletion syndrome

Bassett

Chow²

2008

Curr Psychiatry Rep

212

166

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Abstract22q11.2 deletion syndrome (22qDS) is a genetic syndrome associated with a chromosome 22q11.2 deletion and variable phenotypic expression that commonly includes schizophrenia. Approximately 1% of patients with schizophrenia have 22qDS. The schizophrenia in 22qDS appears broadly similar to that found in the general population with respect to core signs and symptoms, treatment response, neurocognitive profile, and MRI brain anomalies. However, individuals with a 22qDS form of schizophrenia typically have distinguishable physical features, have a lower IQ, and may differ in auxiliary clinical features. IQ, length of 22q11.2 deletions, and COMT functional allele do not appear to be major risk factors for schizophrenia in 22qDS.Ascertainment biases and small sample sizes are limitations of most studies. Larger studies over the lifespan and continuing education about this underrecognized condition are needed. 22qDS-schizophrenia is an important genetic subtype and a valuable model of neurodevelopmental mechanisms involved in the pathogenesis of schizophrenia.

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“…Possibly, ASDs overlap with other disorders, such as the 22q11.2 deletion, in only a few specific subgroups. Subsequent studies should explore this possibility in order to increase our knowledge of potential genetic subtypes of autism (Bassett & Chow, 1999;cf. Ogilvie et al, 2000).…”

Section: Implications and Future Directionsmentioning

confidence: 99%

Autism Spectrum Disorders and Symptoms in Children with Molecularly Confirmed 22q11.2 Deletion Syndrome

Fine

Weissman

Gerdes

et al. 2005

J Autism Dev Disord

193

142

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In this study, we assessed the presence of autism spectrum disorders (ASD) among children with a confirmed 22q11.2 deletion (n = 98). The children's caregivers completed screening measures of ASD behaviors, and for those whose scores indicated significant levels of these behaviors, a standardized diagnostic interview (Autism Diagnostic Interview-Revised; ADI-R) was administered. Results demonstrated that over 20% of children (n = 22) were exhibiting significant levels of autism spectrum symptoms based on the screening measures. Based upon the ADI-R, 14 children qualified for a diagnosis of an ASD, and for 11 of those children a diagnosis of autism was most appropriate. These findings increase our knowledge of developmental disorders associated with the 22q11.2 deletion and point to avenues for future investigation.

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22q11 deletion syndrome: a genetic subtype of schizophrenia

Cited by 296 publications

References 98 publications

The phenotypes of bipolar disorder: relevance for genetic investigations

The phenotypes of bipolar disorder: relevance for genetic investigations

Schizophrenia and 22q11.2 deletion syndrome

Autism Spectrum Disorders and Symptoms in Children with Molecularly Confirmed 22q11.2 Deletion Syndrome

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