Lindex #1743

Goodman AB

Medical Conditions in Ashkenazi Schizophrenic Pedigrees

Schizophrenia Bulletin

1994; 20(3): 507-517

In order to decipher a genetic mechanism for high rates of schizophrenia among the Ashkenazi Jews, the investigator evaluated relatives of 12 known schizophrenia probands (n=974) and 7 normal probands (n=425). The hypothesis tested was whether or not the rare lysosomal enzyme disorders, Tay Sachs disease (TSD), and Gaucher's disease (GD), might contribute to the demonstrated increased vulnerability to schizophrenia in the Ashkenazi Jews. Previous studies have indicated that the rates and relative risks for symptoms characterizing these disorders and for several non autosomal illnesses associated with TSD or GD are significantly elevated in the schizophrenia pedigrees as compared to controls. Other studies have determined wide variability and heterogenicity in both the expression of the disease as well as prevalences among different Jewish ethnic groups. Two studies performed in Israel have reported at least 50% higher incidence of schizophrenia among the European Ashkenazi Jews compared to the non-European Jewish counterpart. They have revealed highest rates in the most religious Ashkenazi enclave in Jerusalem, a neighborhood containing several genetic isolates of immigrants from eastern Europe.

In an attempt to limit the heterogeneity of schizophrenic genotypes, this study has limited itself to the more homogenous Jews of Eastern European origin. The study was further limited to relatives of the pedigree with a diagnosis of schizophrenia or schizo-affective disorder according to the DSM III-R. The control families were selected from volunteers in Jewish community organizations. The relatives were then evaluated for the diagnosis of schizophrenia spectrum illnesses (including schizophrenia, other psychoses, schizoid, schizotypal, or paranoid personality disorder) or at least one of the signs or symptoms of TSD or GD.

Of the 18 probands of schizophrenia evaluated, 6 were excluded for not adequately meeting DSM-III-R criteria for schizophrenia. The mean age of the probands with schizophrenia was 35.3, all with age of onset before 25 years. The rate of schizophrenia in the relatives of the probands (n=974) were 2.23% with the crude rate of 1.75% (17/974) and relative risk of 7.05. The rates of schizophrenia was significantly higher among the families of schizophrenia probands compared with the families of controls (p<0.01). The other psychoses and schizoid and schizotypal personality disorders were also significantly increased in the schizophrenia families (p<0.023). Nonpsychotic depression, dementia, and antisocial personality were also more prevalent among the schizophrenia families, but the findings were not significant. The relative risks for TSD and GD were also elevated among the schizophrenia families, 2.12 for TSD and 3.20 for GD. The frequency for the GD was statistically significantly higher with p value of 0.013. The frequency of TSD was also higher than the control groups, although not statistically significant (see table 1).

Table 1. Rates of schizophrenia spectrum illness and medical conditions in relatives of 123 schizophrenia probands and 7 normal probands. (Reproduced from Schizophrenia Bulletin vol.20, No.3 1994, p. 511)