E. Matsushima

Exploratory eye movements in schizophrenic patients and patients with frontal lobe lesions

SummaryExploratory eye movements in 20 schizophrenics, 18 patients with frontal lobe lesions (9 right-sided and 9 left-sided) and 20 normal controls were examined with an eye mark recorder while they viewed stationary S-shaped figures. The eye movements made during the subjects first 15-s viewing of an original figure were analyzed. Patients with right frontal lobe lesions (RF) and schizophrenics (S) had lower scores than normal controls (NC) for the number of eye fixations, total eye scanning length and mean eye scanning length. Each subject was then shown two other figures slightly different from the original and was requested to compare them with the original. After comparing them, the subject wastasked the question, “Are there any other differences?” The eye movements made over the ensuing 5 s in response to this question were scored using the responsive search score (RSS). The RSS was low only in the S group. The subject was also asked to reproduce the original figure before and after making comparisons between the figures. The RF and S groups were poorer at reproduction than the NC group. These findings suggest that there is disordered function of the right frontal lobe in sehizophrenia, and that schizophrenia is due not only to localized damage to one part of the brain but to more widespread damage.

Family-based association study of markers on chromosome 22 in schizophrenia using African-American, European-American, and Chinese families.

Several studies suggest that loci at chromosome 22q11.2‐q13 might be linked to susceptibility to schizophrenia. Here we performed family‐based association studies on chromosome 22q using 12 DNA microsatellite markers in African‐American, European‐American, and Chinese pedigrees. The marker D22S683 showed significant linkage and association with schizophrenia in not only the European‐American sample but also in a combined sample (European‐American and Chinese samples). Notably, D22S683 is located nearby and between D22S278 and D22S283, which have shown linkage and association to schizophrenia in prior reports. However, we found no significant association for the African‐American sample. In conclusion, our data provide further support for the idea that the region around D22S683 contains a susceptibility gene for schizophrenia.

Family-based association study of the NOTCH4 gene in schizophrenia using Japanese and Chinese samples

BACKGROUND A family based association study in a British sample found the NOTCH4 gene to be associated with schizophrenia; however, all six replication studies failed to confirm the finding. METHODS We performed a family based association study of NOTCH4 and schizophrenia in 123 trios (16 Japanese and 107 Chinese). In addition to the original studys polymorphisms, we examined four new single nucleotide polymorphisms (SNPs)--SNPs_A, B, C and D--around SNP1 of the original study. We genotyped all samples for SNPs_A-D and for SNP1 and (CTG)n of the original study. RESULTS We found no significant associations between NOTCH4 and schizophrenia or its subtypes for all polymorphisms, regardless of gender. The finding remained negative when the Chinese sample was analyzed separately. Exploratory analyses suggested that SNP_A may be associated with early-onset schizophrenia and that SNP1 may be associated with schizophrenia characterized by numerous negative symptoms. CONCLUSIONS NOTCH4 is not a significant susceptibility gene for schizophrenia when clinical heterogeneity is ignored; however, NOTCH4 may be associated with early-onset schizophrenia or schizophrenia with many negative symptoms, but these findings should be interpreted cautiously.