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Brzustowicz LM, Hodgkinson KA, Chow EW, Honer WG, Bassett AS. Location of a major susceptibility locus for familial schizophrenia on chromosome 1q21-q22. Science 2000; 288:678-82. [PMID: 10784452 PMCID: PMC3787922 DOI: 10.1126/science.288.5466.678] [Citation(s) in RCA: 379] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Schizophrenia is a complex disorder, and there is substantial evidence supporting a genetic etiology. Despite this, prior attempts to localize susceptibility loci have produced predominantly suggestive findings. A genome-wide scan for schizophrenia susceptibility loci in 22 extended families with high rates of schizophrenia provided highly significant evidence of linkage to chromosome 1 (1q21-q22), with a maximum heterogeneity logarithm of the likelihood of linkage (lod) score of 6.50. This linkage result should provide sufficient power to allow the positional cloning of the underlying susceptibility gene.
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Abstract
Schizophrenia is a common and serious psychiatric illness with strong evidence for genetic causation, but no specific loci yet identified. Chromosomal abnormalities associated with schizophrenia may help to understand the genetic complexity of the illness. This paper reviews the evidence for associations between chromosomal abnormalities and schizophrenia and related disorders. The results indicate that 22q11.2 microdeletions detected by fluorescence in-situ hybridization (FISH) are significantly associated with schizophrenia. Sex chromosome abnormalities seem to be increased in schizophrenia but insufficient data are available to indicate whether schizophrenia or related disorders are increased in patients with sex chromosome aneuploidies. Other reports of chromosomal abnormalities associated with schizophrenia have the potential to be important adjuncts to linkage studies in gene localization. Advances in molecular cytogenetic techniques (i.e., FISH) have produced significant increases in rates of identified abnormalities in schizophrenia, particularly in patients with very early age at onset, learning difficulties or mental retardation, or dysmorphic features. The results emphasize the importance of considering behavioral phenotypes, including adult onset psychiatric illnesses, in genetic syndromes and the need for clinicians to actively consider identifying chromosomal abnormalities and genetic syndromes in selected psychiatric patients.
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Chow EW, Mikulis DJ, Zipursky RB, Scutt LE, Weksberg R, Bassett AS. Qualitative MRI findings in adults with 22q11 deletion syndrome and schizophrenia. Biol Psychiatry 1999; 46:1436-42. [PMID: 10578458 PMCID: PMC3276598 DOI: 10.1016/s0006-3223(99)00150-x] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND A genetic syndrome associated with schizophrenia, 22q11 deletion syndrome (22qDS), may represent a genetic subtype of schizophrenia (22qDS-Sz). Structural brain changes are common in schizophrenia and may involve developmental anomalies, but there are no data yet for 22qDS-Sz. The objective of this study was to assess brain structure in adults with 22qDS-Sz using magnetic resonance imaging (MRI). METHODS Brain and arterial MRI scans of 11 adults with 22qDS-Sz (mean age = 28.4 years, SD = 6.5) were systematically assessed by a neuroradiologist for qualitative anomalies. RESULTS A high frequency of abnormalities were found: T2 white matter bright foci (BF), 90%; developmental midline anomalies, 45%; cerebral atrophy or ventricular enlargement, 54%; mild cerebellar atrophy, 36%; skull base abnormalities, 55%; and minor vascular abnormalities, 36%. CONCLUSIONS BF and skull base abnormalities, especially in association with neurodevelopmental midline abnormalities, may be distinguishing MRI features for a genetic subtype of schizophrenia involving a deletion on chromosome 22.
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Abstract
22q11 deletion syndrome (22qDS) is due to microdeletions of chromosome region 22q11.2. Little is known about the phenotype of adults. We reviewed available case reports of adults (age >/=18 years) with 22qDS and compared the prevalence of key findings to those reported in a large European survey of 22qDS (497 children and 61 adults) [Ryan et al., 1997: J. Med. Genet. 34:798-804]. Fifty-five studies reported on 126 adults (83 women, 40 men, 3 unknown sex), mean age 29.6 years (SD = 8.7 years). Compared with the European survey, adults with 22qDS reviewed had a lower rate of CHD, 30% versus 75%; chi(2) = 88.65, df = 1, P < 0.0001, but higher rates of identified palate anomalies, 88% versus 15%; chi(2) = 37.45, df = 1, P < 0.0001, and learning difficulties, 94% versus 79%; chi(2) = 12.13, df = 1, P = < 0.0008. The most common finding reported was minor facial anomalies. Few reports provided details of minor physical anomalies. Psychiatric conditions were more prevalent, 36% versus 18%; chi(2)= 5.71, df = 1, P < 0.02, than in the survey: 60% of reviewed adults were transmitting parents (72% mothers) ascertained following diagnosis of affected offspring. They had lower rates of CHD, cleft palate, and psychiatric disorders but similar rates of learning disabilities, and other palate and facial anomalies compared with adults ascertained by other methods. The results suggest that learning disabilities and facial and palate anomalies may be key findings in 22qDS adults, but that ascertainment is a key factor in the observed phenotype. Comprehensive studies of adults with 22qDS identified independently of familial transmission are necessary to further delineate the phenotype of adults and to determine the natural history of the syndrome.
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Abstract
Schizophrenia is likely to be caused by several susceptibility genes and may have environmental factors that interact with susceptibility genes and/or nongenetic causes. Recent evidence supports the likelihood that 22q11 Deletion Syndrome (22qDS) represents an identifiable genetic subtype of schizophrenia. 22qDS is an under-recognized genetic syndrome associated with microdeletions on chromosome 22 and a variable expression that often includes mild congenital dysmorphic features, hypernasal speech, and learning difficulties. Initial evidence indicates that a minority of patients with schizophrenia (approximately 2%) may have 22qDS and that prevalence may be somewhat higher in subpopulations with developmental delay. This paper proposes clinical criteria (including facial features, learning disabilities, hypernasal speech, congenital heart defects and other congenital anomalies) to aid in identifying patients with schizophrenia who may have this subtype and outlines features that may increase the index of suspicion for this syndrome. Although no specific causal gene or genes have yet been identified in the deletion region, 22qDS may represent a more homogeneous subtype of schizophrenia. This subtype may serve as a model for neurodevelopmental origins of schizophrenia that could aid in delineating etiologic and pathogenetic mechanisms.
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Brzustowicz LM, Honer WG, Chow EW, Little D, Hogan J, Hodgkinson K, Bassett AS. Linkage of familial schizophrenia to chromosome 13q32. Am J Hum Genet 1999; 65:1096-103. [PMID: 10486329 PMCID: PMC1288243 DOI: 10.1086/302579] [Citation(s) in RCA: 169] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/1999] [Accepted: 07/21/1999] [Indexed: 11/03/2022] Open
Abstract
Over the past 4 years, a number of investigators have reported findings suggestive of linkage to schizophrenia, with markers on chromosomes 13q32 and 8p21, with one recent study by Blouin et al. reporting significant linkage to these regions. As part of an ongoing genome scan, we evaluated microsatellite markers spanning chromosomes 8 and 13, for linkage to schizophrenia, in 21 extended Canadian families. Families were analyzed under autosomal dominant and recessive models, with broad and narrow definitions of schizophrenia. All models produced positive LOD scores with markers on 13q, with higher scores under the recessive models. The maximum three-point LOD scores were obtained under the recessive-broad model: 3.92 at recombination fraction (theta).1 with D13S793, under homogeneity, and 4.42 with alpha=.65 and straight theta=0 with D13S793, under heterogeneity. Positive LOD scores were also obtained, under all models, for markers on 8p. Although a maximum two-point LOD score of 3.49 was obtained under the dominant-narrow model with D8S136 at straight theta=0.1, multipoint analysis with closely flanking markers reduced the maximum LOD score in this region to 2. 13. These results provide independent significant evidence of linkage of a schizophrenia-susceptibility locus to markers on 13q32 and support the presence of a second susceptibility locus on 8p21.
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Bassett AS. Progress on the genetics of schizophrenia. J Psychiatry Neurosci 1998; 23:270-3. [PMID: 9846030 PMCID: PMC1188953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
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Bassett AS, Hodgkinson K, Chow EW, Correia S, Scutt LE, Weksberg R. 22q11 deletion syndrome in adults with schizophrenia. AMERICAN JOURNAL OF MEDICAL GENETICS 1998; 81:328-37. [PMID: 9674980 PMCID: PMC3173497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Genetic syndromes associated with deletions at chromosome 22q11 generally have been diagnosed during childhood based on a constellation of physical features. To investigate a reported association of velocardiofacial syndrome with psychotic disorders in adults, we assessed subjects with DSM-IV schizophrenia or schizoaffective disorder who were referred with two or more syndromal features (palatal, cardiac, facial, or other congenital anomalies, and/or learning difficulties). We report on 10 subjects (5 men and 5 women), mean age 27.2 (SD 6.0) years, who were found to have a 22q11 deletion at locus D22S75 using fluorescence in-situ hybridization (FISH). The mean age at onset of psychosis was 19.6 (SD 4.6) years. Symptoms and course of the psychotic illnesses were unremarkable, but additional signs such as temper outbursts were common. These adult subjects had significantly fewer major palatal (P = .0001) and conotruncal cardiac (P = .05) anomalies but the same high rate of learning difficulties as a sample with deletion 22q11 ascertained through a pediatric clinic [Lindsay et al. (1995): Am J Med Genet 57:514-522]. Minor congenital features and rate of transmitted cases were similar to those previously reported. These results replicate the association of a 22q11 deletion syndrome with schizophrenia and confirm the importance of ascertainment in influencing the phenotype found. The findings support a developmental gene in the 22q11 deletion region causing a complex phenotype which may include significant behavioral components that emerge over time. We support using the term "22q11 deletion syndrome (22DS)," which would encompass physical and psychiatric features, and could also be applied to describe a genetic subtype of schizophrenia.
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Husted J, Scutt LE, Bassett AS. Paternal transmission and anticipation in schizophrenia. AMERICAN JOURNAL OF MEDICAL GENETICS 1998; 81:156-62. [PMID: 9613855 PMCID: PMC3169647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent studies have observed anticipation (earlier age at onset (AAO) or increased disease severity in successive generations) in familial schizophrenia. In other disorders, where the molecular mechanism (repeat expansion) is known, anticipation varies in degree depending on the sex of the transmitting parent. We investigated parental sex effects on anticipation in schizophrenia, using a familial sample of affected two-generation pairs in which anticipation had previously been demonstrated using the median intergenerational difference (MID) in AAO. A Wilcoxon rank sum test for independent samples was used to determine whether MID in AAO was significantly different for paternal and maternal transmission. Results suggested that in a sample of 127 parent-offspring pairs, anticipation was greater with paternal than with maternal transmission (MID = 18 and 14 years, respectively, P = 0.05). Paternal effects were strongest in 39 parent-offspring pairs with early-onset offspring (< or = 21 years) (MID = 22 and 17 years, respectively, for paternal and maternal transmission, P = 0.01). However, assessment of the effect of possible selection biases suggests that preferential ascertainment of late-onset fathers may have exerted important effects. While the results support possible paternal effects, further studies are needed to draw firm conclusions about true parent-of-origin effects on anticipation in familial schizophrenia.
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Brzustowicz LM, Honer WG, Chow EW, Hogan J, Hodgkinson K, Bassett AS. Use of a quantitative trait to map a locus associated with severity of positive symptoms in familial schizophrenia to chromosome 6p. Am J Hum Genet 1997; 61:1388-96. [PMID: 9399881 PMCID: PMC1716068 DOI: 10.1086/301623] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A number of recent linkage studies have suggested the presence of a schizophrenia susceptibility locus on chromosome 6p. We evaluated 28 genetic markers, spanning chromosome 6, for linkage to schizophrenia in 10 moderately large Canadian families of Celtic ancestry. Parametric analyses of these families under autosomal dominant and recessive models, using broad and narrow definitions of schizophrenia, produced no significant evidence for linkage. A sib-pair analysis using categorical disease definitions also failed to produce significant evidence for linkage. We then conducted a separate sibpair analysis using scores on positive-symptom (psychotic), negative-symptom (deficit), and general psychopathology-symptom scales as quantitative traits. With the positive symptom-scale scores, the marker D6S1960 produced P = 1.2 x 10(-5) under two-point and P = 5.4 x 10(-6) under multipoint analyses. Using simulation studies, we determined that these nominal P values correspond to empirical P values of .034 and .0085, respectively. These results suggest that a schizophrenia susceptibility locus on chromosome 6p may be related to the severity of psychotic symptoms. Assessment of behavioral quantitative traits may provide increased power over categorical phenotype assignment for detection of linkage in complex psychiatric disorders.
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Erlenmeyer-Kimling L, Adamo UH, Rock D, Roberts SA, Bassett AS, Squires-Wheeler E, Cornblatt BA, Endicott J, Pape S, Gottesman II. The New York High-Risk Project. Prevalence and comorbidity of axis I disorders in offspring of schizophrenic parents at 25-year follow-up. ARCHIVES OF GENERAL PSYCHIATRY 1997; 54:1096-102. [PMID: 9400345 PMCID: PMC3188309 DOI: 10.1001/archpsyc.1997.01830240052008] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The New York High-Risk Project is a study of offspring of patients with schizophrenia (HRSz group) or affective illness (HRAff group) and psychiatrically normal parents (NC group) observed prospectively from childhood to adulthood. We herein present lifetime prevalence and comorbidity rates of Axis I disorders in subjects and their siblings from sample A of the project. METHODS Schedule for Affective Disorders and Schizophrenia-Lifetime Version interviews conducted with the offspring in adulthood were used to obtain diagnoses of Axis I disorders. RESULTS Schizophrenia and unspecified psychoses occurred only in the HRSz group. However, schizoaffective and psychotic affective disorders occurred equally in the HRSz and HRAff groups. Total rates of psychosis in these groups were significantly higher than in the NC group. All groups had similar rates of nonpsychotic affective and substance abuse disorders. The HRAff group, however, had significantly more total affective illness than the NC group and tended to have more anxiety disorders than the other groups. Comorbidity rates in the HRSz and HRAff groups were nearly twice those of the NC group. CONCLUSIONS The familial liabilities to schizophrenia and affective disorders show specificities and commonalities, differing markedly from each other in their expression of some disorders and sharing others. Patterns of comorbidity are generally, although not entirely, similar to these liabilities.
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Smith GN, Flynn SW, Kopala LC, Bassett AS, Lapointe JS, Falkai P, Honer WG. A comprehensive method of assessing routine CT scans in schizophrenia. Acta Psychiatr Scand 1997; 96:395-401. [PMID: 9395159 PMCID: PMC3169641 DOI: 10.1111/j.1600-0447.1997.tb09935.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Morphological brain abnormalities are common in schizophrenia, although the aetiological and clinical significance of these findings is largely unknown. Substantial between-subject variability suggests that large samples are needed to study the full implications of brain pathomorphology. Computerized tomography (CT) is frequently used routinely in schizophrenia, and large numbers of scans are available for study. This article describes the development and statistical properties of a rapid and simple method of assessing CT scans. The CT Rating Scale for Schizophrenia (CTRSS) is minimally affected by variability in scanning procedures, is reliable, and accurately estimates area and volumetric measures of brain spaces. By promoting the comprehensive assessment of large numbers of routinely obtained scans, the CTRSS would allow the investigation of variables that may systematically affect results (e.g. gender and age) and variables with low prevalence. The CTRSS provides a useful adjunct to technologically more sophisticated methods of assessment such as magnetic resonance imaging (MRI).
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King N, Bassett AS, Honer WG, Masellis M, Kennedy JL. Absence of linkage for schizophrenia on the short arm of chromosome 5 in multiplex Canadian families. AMERICAN JOURNAL OF MEDICAL GENETICS 1997; 74:472-4. [PMID: 9342193 PMCID: PMC3169645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A VNTR for the human dopamine transporter gene (DAT-1) has been localized to chromosome 5p15.3. Silverman et al. [1996] found evidence for genetic linkage of the D5S111 locus, located just centromeric to DAT-1, to schizophrenia and related disorders in a large Hispanic family. We evaluated five markers on 5p, including D5S111 and the DAT-1 VNTR, in five multiplex schizophrenic families, assuming autosomal dominant transmission (subjects assessed n = 122, DNAs available n = 96, individuals with schizophrenia and schizoaffective disorder n = 36, broader spectrum disorders n = 14). LOD scores were negative across all families for all markers tested, and overall LOD scores were strongly negative (<-2.0, theta = 0) across all five families for each of the markers typed. Thus, there is no evidence to support the linkage of markers in this region of chromosome 5 to schizophrenia in this sample of families.
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Bassett AS, Husted J. Anticipation or ascertainment bias in schizophrenia? Penrose's familial mental illness sample. Am J Hum Genet 1997; 60:630-7. [PMID: 9042924 PMCID: PMC1712532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Several studies have observed anticipation (earlier age at onset [AAO] in successive generations) in familial schizophrenia. However, whether true anticipation or ascertainment bias is the principal originating mechanism remains unclear. In 1944 L. S. Penrose collected AAO data on a large, representative sample of familial mental illness, using a broad ascertainment strategy. These data allowed examination of anticipation and ascertainment biases in five two-generation samples of affected relative pairs. The median intergenerational difference (MID) in AAO was used to assess anticipation. Results showed significant anticipation in parent-offspring pairs with schizophrenia (n = 137 pairs; MID 15 years; P = .0001) and in a positive control sample with Huntington disease (n = 11; P = .01). Broadening the diagnosis of the schizophrenia sample suggested anticipation of severity of illness. However, other analyses provided evidence for ascertainment bias, especially in later-AAO parents, in parent-offspring pairs. Aunt/uncle-niece/nephew schizophrenia pairs showed anticipation (n = 111; P = .0001), but the MID was 8 years and aunts/uncles had earlier median AAO than parents. Anticipation effects were greatest in pairs with late-AAO parents but remained significant in a subgroup of schizophrenia pairs with early parental AAO (n = 31; P = .03). A small control sample of other diseases had MID of 5 years but no significant anticipation (n = 9; P = .38). These results suggest that, although ascertainment-bias effects were observed in parent-offspring pairs, true anticipation appears to be inherent in the transmission of familial schizophrenia. The findings support investigations of unstable mutations and other mechanisms that may contribute to true anticipation in schizophrenia.
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Abstract
The hypothesis of a neurodevelopmental dysfunction being involved in the etiology of schizophrenia is suggested by the observation of morphological alterations in the brains of schizophrenia patients. These alterations may be caused by defects in neural cell differentiation or migration, which could lead to disrupted neuronal circuitry and to the schizophrenia symptomatology. The neural cell adhesion molecule (NCAM) plays a major role in cell migration and axon outgrowth, and is involved in synaptic plasticity mechanisms implicated in adult cognitive functions. Altered levels of the NCAM polysialylated form, PSA-NCAM, in the brain of schizophrenia patients have been reported, and are supportive of a role for this molecule in the disorder. To investigate the possible involvement of the NCAM gene in schizophrenia, we conducted a comprehensive genetic study, which included linkage analysis and an association study employing the Haplotype Relative Risk (HRR) design in nuclear families. Our results indicate that structural alterations in the NCAM gene are unlikely to play a major role in schizophrenia, although a function for the NCAM molecule in the etiology of the disease remains an intriguing hypothesis.
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Bassett AS, Chow EW, Bury A, Ali F, Haylock CA, Smith GN, Lapointe JS, Honer WG. Increased head circumference in schizophrenia. Biol Psychiatry 1996; 40:1173-5. [PMID: 8931921 PMCID: PMC3154171 DOI: 10.1016/s0006-3223(96)00288-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Petronis A, Bassett AS, Honer WG, Vincent JB, Tatuch Y, Sasaki T, Ying DJ, Klempan TA, Kennedy JL. Search for unstable DNA in schizophrenia families with evidence for genetic anticipation. Am J Hum Genet 1996; 59:905-11. [PMID: 8808607 PMCID: PMC1914813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Evidence for genetic anticipation has recently become an important subject of research in clinical psychiatric genetics. Renewed interest in anticipation was evoked by molecular genetic findings of a novel type of mutation termed "unstable DNA." The unstable DNA model can be construed as the "best fit" for schizophrenia twin and family epidemiological data. We have performed a large-scale Southern blot hybridization, asymmetrical PCR-based, and repeat expansion-detection screening for (CAG)n/(CTG)n and (CCG)n/(CGG)n expansions in eastern Canadian schizophrenia multiplex families demonstrating genetic anticipation. There were no differences in (CAG)n/(CTG)n and (CCG)n/(CGG)n pattern distribution either between affected and unaffected individuals or across generations. Our findings do not support the hypothesis that large (CAG)n/(CTG)n or (CCG)n/(CGG)n expansions are the major etiologic factor in schizophrenia. A separate set of experiments directed to the analysis of small (30-130 trinucleotides), Huntington disease-type expansions in individual genes is required in order to fully exclude the presence of (CAG)n/(CTG)n- or (CCG)n/(CGG)n-type unstable mutation.
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Abstract
BACKGROUND Reproductive fitness is an important factor in understanding inheritance in genetic disorders. The purpose of this study was to determine whether fitness is reduced in familial schizophrenia (FS) and if fitness in siblings differs from the norm. METHOD The number of offspring in 36 subjects with RDC schizophrenia or schizoaffective disorder (SZ) and their 101 siblings from large FS families was compared with age-adjusted census figures. RESULTS Fitness in the SZ group was significantly reduced: 23% of expected in males and 51% of expected in females. Fitness of unaffected siblings was within census expectations. However, female siblings with schizophrenia spectrum features had increased fitness over census norms. Reduced fitness was correlated with low marital rates, poor functioning and positive symptoms. CONCLUSIONS These results indicate that reduced fitness is an important genetic force in FS and is likely inherent to the illness. Sex differences are important and would need to be considered when examining maternal and paternal transmission of schizophrenia. The results support a proposed high mutation rate for schizophrenia, consistent with a dynamic mutation mechanism.
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Wakem P, Ikeda S, Haake A, Polakowska R, Ewing N, Sarret Y, Duvic M, Berg D, Bassett A, Kennedy JL, Tuskis A, Epstein EH, Goldsmith LA. Localization of the Darier disease gene to a 2-cM portion of 12q23-24.1. J Invest Dermatol 1996; 106:365-7. [PMID: 8601743 PMCID: PMC3160983 DOI: 10.1111/1523-1747.ep12343145] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Positional cloning with microsatellite markers allowed further localization of the Darier disease gene to a 2-cM interval of chromosome 12, 12q23-24.1, between the polymorphic loci D12S234 and D12S129. A region this size is suitable for construction of a contig to identify the Darier disease gene. Use of a polymorphic intronic marker for nitric oxide synthetase 1 gene, which maps to the same chromosomal area as the Darier gene, allowed exclusion of that gene as the Darier disease gene.
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O'Malley MP, Bassett AS, Honer WG, Kennedy JL, King N, Berg D. Linkage analysis between schizophrenia and the Darier's disease region on 12q. Psychiatr Genet 1996; 6:187-90. [PMID: 9149323 PMCID: PMC3160984 DOI: 10.1097/00041444-199624000-00003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
There have been reports of an association between Darier's disease, an autosomal dominant genodermatosis, and psychiatric illness. Recently the gene causing Darier's disease has been mapped to an area on 12q, between D12S58 and D12S84. The findings of linkage analysis of 4 markers in the Darier's disease region on 12q in five families segregating schizophrenia are presented. They fail to support close linkage between schizophrenia and the Darier's disease region on 12q.
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Honer WG, Bassett AS, Falkai P, Beach TG, Lapointe JS. A case study of temporal lobe development in familial schizophrenia. Psychol Med 1996; 26:191-195. [PMID: 8643758 PMCID: PMC3169646 DOI: 10.1017/s0033291700033821] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Case studies of patients with familial schizophrenia may help to define the pathophysiology of this illness and indicate potential candidate genes for genetic linkage studies. In this regard, the clinical, radiological and pathological assessments of a 39-year-old affected man from a pedigree with familial schizophrenia are presented. Brain imaging with CT indicated moderate cortical atrophy, particularly of the temporal lobes. Neuropathological examination revealed granular ependymitis, indicating possible past ventricular pathology. Granular ependymitis was reported to occur in genetic developmental disorders with neuronal migration abnormalities. In the present case, heterotopic clusters of neurons were visualized in the entorhinal cortex, suggesting that temporal lobe development was not entirely normal. This case study suggests that genetic factors could be investigated further as one possible aetiology of certain neurodevelopmental abnormalities observed in schizophrenia.
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Honer WG, Bassett AS, Squires-Wheeler E, Falkai P, Smith GN, Lapointe JS, Canero C, Lang DJ. The temporal lobes, reversed asymmetry and the genetics of schizophrenia. Neuroreport 1995; 7:221-4. [PMID: 8742456 PMCID: PMC3160973 DOI: 10.1097/00001756-199512290-00053] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mechanisms determining temporal lobe structural asymmetries may be involved in the pathogenesis of schizophrenia. To investigate the temporal lobes in familial schizophrenia, computed tomographic scans were obtained from 51 subjects (seven families). Enlargement of sylvian fissures and temporal lobe sulcal spaces was observed in family members with schizophrenia. The posterior one-third of the sylvian fissure was larger on the left side in subjects with schizophrenia, and larger on the right side in unaffected individuals. This disturbed pattern of posterior sylvian fissure asymmetry suggests that adjacent language regions may be affected in schizophrenia. An intermediate degree of disturbance in subjects who had schizophrenia-related illnesses or were obligate carriers suggests that genetic factors may be important determinants of temporal lobe asymmetries in familial schizophrenia.
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Erlenmeyer-Kimling L, Squires-Wheeler E, Adamo UH, Bassett AS, Cornblatt BA, Kestenbaum CJ, Rock D, Roberts SA, Gottesman II. The New York High-Risk Project. Psychoses and cluster A personality disorders in offspring of schizophrenic parents at 23 years of follow-up. ARCHIVES OF GENERAL PSYCHIATRY 1995; 52:857-65. [PMID: 7575106 PMCID: PMC3188304 DOI: 10.1001/archpsyc.1995.03950220067013] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND We herein present lifetime prevalence rates of psychoses and DSM-III-R cluster A personality disorders in sample A of the New York High-Risk Project, a prospective study following offspring of parents with schizophrenia (HRSz subjects) and affective illness (HRAff subjects) and of psychiatrically normal parents (NC subjects) from midchildhood to adulthood. METHODS We interviewed the offspring in adulthood with the Schedule for Affective Disorders and Schizophrenia, Lifetime Version, for Axis I disorders and the Personality Disorder Examination for Axis II disorders. RESULTS Lifetime prevalence rates (+/- SE) of schizophrenia and unspecified psychosis were 11.1% +/- 4.3% and 5.6% +/- 3.1%, respectively, in the HRSz group and 0% in the HRAff and NC groups. Rates of schizoaffective disorder subclassified as mainly schizophrenic, however, were highest in the HRAff group. Rates of psychotic affective disorders did not differ between the HRSz and other groups. Age-corrected morbidity risks were similar to lifetime prevalence rates. Rates of the three cluster A personality disorders did not differ among the groups, but the combined rate was greater in the HRSz and HRAff groups than in the NC group. CONCLUSIONS Our data strongly support a specific familial liability to narrowly defined schizophrenia that is not shared by families of probands with affective disorder. Schizoaffective disorder and cluster A personality disorders, however, occur in families of both schizophrenic probands and probands with affective disorder. Psychotic affective disorders, which are not increased in HRSz subjects, do not appear to be an expression of the liability to schizophrenia.
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Chow EW, Collins EJ, Nuttall SE, Bassett AS. Clinical use of clozapine in a major urban setting: one year experience. J Psychiatry Neurosci 1995; 20:133-40. [PMID: 7703222 PMCID: PMC1188672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
This paper examines the clinical and demographic data of patients in the Clozapine Distribution System in Metropolitan Toronto in the first year after its inception. One hundred and thirty-seven patients were approved for funding during the year. They tended to be young, chronically and markedly ill patients suffering from schizophrenia, primarily with treatment resistance as the reason for clozapine therapy. Only 55 patients completed at least six months of therapy; 15 patients discontinued clozapine before six months of treatment, mainly because of side-effects and/or patients' noncompliance with bloodwork. Three patients discontinued clozapine because of haematological compromise. Clozapine was efficacious for the majority of patients who took it for at least six months, with improvement in all six clinical dimensions examined in the study. Nevertheless, the number of early discontinuation patients significantly lowered the overall effectiveness of clozapine in actual clinical practice.
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Kennedy JL, Berg D, Bassett AS, Roy R, King N, Perkins M. Genetic linkage for Darier disease (keratosis follicularis). AMERICAN JOURNAL OF MEDICAL GENETICS 1995; 55:307-10. [PMID: 7537018 PMCID: PMC3160971 DOI: 10.1002/ajmg.1320550312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Darier disease is an autosomal dominant skin disorder characterized by abnormal keratinocyte adhesion. Recent data have provided evidence for linkage of the Darier disease locus to 12q23-24.1 in British families. We have carried out linkage analysis using the 12q markers D12S58, D12S84, D12S79, D12S86, PLA2, and D12S63 in 6 Canadian families. Pairwise linkage analysis generated positive lod scores at all 6 markers at various recombination fractions, and each family showed positive lod scores with more than one marker. The peak lod score in the multipoint analysis (Zmax) was 5.5 in the interval between markers D12S58 and D12S84. These positive lod scores in North American families of varied European ancestry confirm the location of the Darier disease gene, and suggest genetic homogeneity. The future identification and sequencing of the gene responsible for Darier disease should lead to improved understanding of the disease and of keratinocyte adhesion in general.
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