Suggestive linkage of schizophrenia to 5p13 in Costa Rica.

Schizophrenia afflicts roughly 1% of all people worldwide. Remarkably, despite differing cultures and environments, the expression of illness is essentially the same. Family, twin, and adoption studies identify schizophrenia as a genetically influenced disease. Linkage studies suggest many positive regions of interest, but as a complex genetic disorder most of the pathogenic loci have not yet been found. Isolated populations are commonly used to study rare Mendelian inherited diseases due to the more homogenous genetic background of the subjects and are thought to be useful for detecting linkage in complex genetic disorders such as schizophrenia. This study aims to define areas of the genome that exhibit co-inheritance with schizophrenia in one large, Mendelian-like family from the central valley of Costa Rica. The whole genome scan analysis of this pedigree, which included 11 cases of schizophrenia and schizoaffective disorder, identified a number of markers on chromosome 5p that appear to co-segregate with the disease with a maximum lod score of 2.70 at marker D5S426. Current studies include investigating additional Costa Rican pedigrees to replicate these findings and identify additional loci linked to the disease.

Clinical characteristics of schizophrenia in multiply affected Spanish origin families from Costa Rica.

Sixty-six families from Costa Rica with multiply ill sets of siblings were examined in detailed clinical evaluations and compared with 59 similarly evaluated families from the USA. Eighty-six unrelated Costa Rican individuals with a schizophrenia spectrum diagnosis and no other ill siblings were an additional comparison group. This study was undertaken to examine whether schizophrenia in Costa Rica has similar clinical and demographic characteristics to that in the USA, whether a homogeneous population such as that in Costa Rica might harbor a specific definable subtype, and whether singletons have similar or differing characteristics from individuals in multiplex families. Overall, schizophrenia in Costa Rica is similar to that in any other geographic location. The same symptoms, sex ratio and age of onset characteristics predominate. However, there was significantly less prevalence of affective symptoms (depression and mania) and drug abuse among the Costa Rican multiplex families by comparison with those from the USA. The families with only one ill member from Costa Rica had significantly more alcohol abuse than the multiply affected families. Within multiplex families (both USA and Costa Rica), age of onset was found to have a familial component. Family sibship size was significantly greater in Costa Rica than the USA for the generation with illness studied. However, these siblings had overall fewer children. In Costa Rica, the male but not the female siblings with schizophrenia had reduced fecundity compared with their well siblings. These families from Costa Rica will be used in further molecular genetic studies to determine whether the illness etiology can be traced to one or more specific genetic linkages.