HLA antigens in patients with schizophrenic syndromes

The 3DPT dimensions S, E, and N: A critical evaluation of Eysenck's Psychoticism model

In this article a critical evaluation is given of Eysenck's Psychoticism model. It is argued that in this model two sub‐models can be distinguished, which, contrary to Eysenck's presentation, cannot be regarded as true extensions of each other. With respect to one of these models, the ‚genotypic’︁ P‐model, the theory is criticized in that both schizophrenia and affective psychosis are determined by a common genetic predisposition which can phenotypically manifest itself in variations of P. Instead of this theory, the likelihood is put forward that a high EPQ‐P score, albeit in combination with a high N and a low E score (and notwithstanding the fact that criminals or psychopaths can also obtain high P scores), is (only) related to the schizoid state, and hence, that P seems to be relevant either as a predisposing factor contributing to the development of schizophrenic psychosis, or as a factor on which biological relatives of schizophrenics obtain higher scores on average than normals do. In this respect, Eysenck's theory that the non‐schizoid form of psychopathy can also be found among first‐degree relatives of schizophrenics, and hence, that psychopathy and schizoidia are genetically related, is also criticized. Furthermore, it is argued that Eysenck's EPQ‐P scale is not optimal for measuring those traits of the schizoid personality which are independent of N and/or E. Both arguments regarding the contents of this scale and arguments with respect to the demonstrated lack of invariance of the EPQ‐P factor are adduced to support this statement. Thus, an alternative scale for measuring ‚P’︁ (labelled S or Insensitivity) was designed by us. The S‐scale is based on literature concerning the schizoid state and reflects the results of a series of principal components analyses of (potential) S items, together with N and E items, put into execution with the intention of investigating the invariance of the S factor (and of E and N) with respect to six sample and other parameters. These investigations were carried out on a large, representative sample of the Dutch population. Additional investigations were carried out concerning the reliability and validity of the three newly formed scales. The results of these investigations turned out to be very satisfactory or, in some respects, at least promising. Finally, in this article, comments are made on the nature of the S factor, comparing this dimension with both Eysenck's P factor and the dimensions Agreeableness and Conscientiousness, as proposed, for instance, in McCrae and Costa's version of Nor‐man's 5‐factor model. As against P, the S or Insensitivity factor seems to be only (negatively) related to Agreeableness and not to Conscientiousness. It is also argued that this finding seems to be in accord with the supposed schizoid nature of S and the criticisms levelled at Eysenck's EPQ‐P scale.

Schizophrenia and HLA: a review

A number of reports of genetic association of human leucocyte antigens (HLA) and alleles with schizophrenia have recently been published. A schizophrenia locus on chromosome 6p near the HLA region has also been reported, on the basis of linkage studies. We have therefore reviewed the investigations of association of HLA with schizophrenia published from 1974 to date, and have also briefly reviewed the chromosome 6p linkage studies. Two or more groups of investigators have reported association of each of the following HLA antigens or alleles with schizophrenia - A9 or its A24 subspecificity, A28, A10, DRB1*01 and DRw6. However, these results may represent Type I errors caused by small sample size, inappropriate diagnostic, laboratory and/or statistical methodology, and/or incorrectly chosen comparison subjects. Hypothesis-driven negative associations of DRB1*04 and DQB1*0602 with schizophrenia have also been reported. Taken together, however, HLA association investigations provide only weak evidence for the existence of either resistance or susceptibility loci for schizophrenia close to the HLA region at the 6p21.3 band and, indeed, recently reported investigations that controlled for most of these confounders found no evidence of association. Linkage studies suggest that a susceptibility locus may exist and that it may be within the HLA region, but again the evidence is far from conclusive. Further HLA association investigations should employ operational diagnostic criteria, comparison subjects screened for illness and HLA genotyping, and should include both association studies of candidate alleles and transmission disequilibrium and haplotype relative risk studies.

HLA antigens in childhood onset schizophrenia

Evidence of immune system abnormalities in adult schizophrenia has prompted examination of the human leukocyte antigen (HLA) system. Childhood onset schizophrenia offers a unique opportunity to test neurodevelopmental hypotheses of schizophrenia, including those which implicate components of the immune system. In the present study, class I and II HLA antigens were typed using sequence-specific primers and the polymerase chain reaction in 28 childhood onset schizophrenics and 51 ethnically matched healthy subjects. Groups were compared for frequencies of HLA antigens reported to be associated with schizophrenia and/or autoimmune disorders. We hypothesized that antigen frequencies would differ between schizophrenic and healthy children, suggesting that some dimension of the neurodevelopmental disturbance experienced by these children may be mediated by subtle abnormalities of immune function. There were no significant differences between schizophrenic and healthy subjects in the frequency of any antigen tested. These findings do not support HLA-associated pathology in childhood onset schizophrenia.

A negative association of schizophrenia with an allele of the HLA DQB1 gene among African-Americans

Using polymorphisms of the human leukocyte antigen (HLA) DQB1 gene, a case-control study was conducted in a group of patients with schizophrenia (DSM-III, n = 58) and psychiatrically normal controls matched for ethnicity (n = 72), living in the same geographical area. A significant negative association of allele HLA DQB1*0602 with schizophrenia was present among African-Americans (odds ratio 0.19), but could not be detected in Caucasians.

Relationship of HLA to schizophrenia in 10 nuclear families

We tested the hypothesis of linkage of HLA (human leukocyte antigens) and schizophrenia in 10 nuclear families that were ascertained on the basis of at least two siblings affected with chronic schizophrenia (SCH), as defined by Research Diagnostic Criteria, with or without superimposed affective disorder. All available parents and siblings were interviewed and typed for HLA antigens at the A, B, C, and Dr loci. Lod scores for linkage between HLA and a putative SCH-locus were calculated using the program LIPED, assuming several possible models for the mode of transmission of the SCH locus. Linkage was also tested with DSM-III schizotypal and paranoid personality disorders considered as part of the illness phenotype. The lod score analysis indicated that for most models of inheritance of schizophrenia, close linkage to HLA could be excluded. The results did not change if individuals with "spectrum" disorders were considered affected. We also tested for linkage using the affected sib-pair method which does not require any assumptions about the mode of transmission of the illness. The results of this analysis also indicated that linkage to HLA was very unlikely. If our results are considered together with other published studies, a susceptibility locus for schizophrenia or "schizophrenia spectrum" is not likely to be in the HLA region of chromosome 6.

HLA antigens and subtypes of schizophrenia

Studies on HLA antigens in schizophrenia have produced conflicting results, but there has been greater agreement when clinical subtypes of the disorder have been separated. In view of this, we reassessed 68 previously studied patients with hospital diagnoses of schizophrenia and, while blind to their HLA types, used operational criteria to define clinical subtypes. We compared and combined the results with those from all available similar studies. Those of our patients who fulfilled operational criteria for paranoid schizophrenia showed a nonsignificant increase in HLA A9 as compared with controls. The magnitude of the increase was similar to that from all previous reports, and when data from all sources were combined, the evidence for an association between HLA A9 and paranoid schizophrenia was consistent and highly significant. Patients who were diagnosed as suffering from hebephrenic schizophrenia showed significant increases in HLA A1 and B8 compared with controls. An association between hebephrenia and A1, but not B8, remained on combining the results with those of other studies.

HLA antigens and schizophrenia: a pool of two studies

Results from two studies on HLA antigens in schizophrenic patients were pooled and analyzed. A statistically significant difference appeared in the frequency for HLA-B27, which was increased in the patient group (n = 164) as compared to the controls (n = 585). The strong correlation between this antigen and some forms of arthropathies and the fact that arthropathies and schizophrenia very seldom occur in the same individual suggest that HLA-B27 could serve as a genetic marker for both diseases. The development of either one or the other may depend upon the interplay between the genetic marker (HLA-B27) and other biological and environmental factors. In addition to the potential value of HLA-B27 as a marker for vulnerability to schizophrenia, the human leucocyte antigens may also serve to differentiate between various subtypes of the illness.

HLA antigens in affective disorders and schizophrenia

The distribution of HLA antigen frequencies has been studied in patients with affective disorders. There were no significant differences between bipolar patients, unipolar patients, or controls. Preliminary data on HLA antigen distribution in schizophrenic patients are reported. Our negative results in affective disorders are discussed in relation to HLA studies reported from other laboratories, with special reference to some potential methodological problems.

Gc serum groups and schizophrenia

In an epidemiological study of schizophrenia in a North Swedish isolate, Böök et al. (1978) reported an association between schizophrenia and the genetic marker Gc2. In an attempt to confirm this observation, we examined a series of schizophrenic patients from Västerbotton County in Northern Sweden. In our material there was no difference between schizophrenic patients and controls with respect to the frequencies of Gc groups or genes. A reanalysis of the material by Böök et al. (1978) showed that schizophrenics compared to controls had a significant increase in the frequency of the Gc 2-1 group, but not of the Gc2 gene. The Gc distribution in the material by Böök et al. (1978) was similar to that previously reported by us in a series of patients with cycloid psychosis.