In particular, no study has simultaneously investigated the relationship between smooth pursuit and saccadic system among schizophrenic patients. Only one study used abnormal smooth pursuit as an endophenotype in a linkage study reporting linkage of pursuit EMD to chromosome 6.6 However, these results need to be replicated. Cognitive markers Numerous studies suggest that relatives of schizophrenic find more patients exhibit neuropsychological impairments that are milder than, and yet similar to, those observed in schizophrenic patients. In particular, the relatives of schizophrenic patients have been demonstrated to show Inhibitors,research,lifescience,medical disturbances of
executive functioning, verbal memory, auditory attention, mental control, and verbal ability.88 These abnormalities are stable over time89 Inhibitors,research,lifescience,medical and are observed in nonschizophrenic family members of patients; moreover, nonschizophrenic, monozygotic cotwins produce more persevering responses in the Wisconsin Card Sorting Test than controls.90-91 Another relevant strategy to identify endophenotypes is to perform high-risk studies on offspring of schizophrenic patients. Offspring were shown to have attention difficulties, poor performance on memory
tasks, poor global adjustment, poor social competence, and anhedonia.92 Abnormalities in verbal short-term memory, related to amplitude decrements in the P300 component of ERP, and attention digit-span Inhibitors,research,lifescience,medical tasks predicted 83% of the offspring who developed adulthood schizophrenia.93 Before demonstrating that a neurocognitive abnormality is an endophenotype, many variables must be tested for replicability over studies, stability over time, and heritability. Conclusions Altogether, research into the genetic basis of schizophrenia Inhibitors,research,lifescience,medical is productive but complex, and can be frustrating. Nevertheless, the field is slowly moving toward new methods of analysis, by searching alternative phenotypic
definition and Inhibitors,research,lifescience,medical making collaborative efforts to gather samples large enough for analysis.
Agrowing number of neurodegenerative disorders have been found to belong to the group of CAG triplet repeat disorders, including Huntington’s disease (HD), spinal and bulbar muscular atrophy (SBMA), dentatorubral palidoluysian atrophy, Machado-Joseph disease/spinocerebellar ataxia type 3, and spinocerebellar ataxias types aminophylline 1, 2, 6, and 71. All these illnesses are caused by an elongated CAG repeat located in the coding region of the respective genes, which is translated into a polyglutamine tract. The mechanism by which CAG repeats elongate is currently unknown and is the subject of intensive investigation.2 Characteristic features of CAG repeat disorders are autosomal dominant inheritance (except SBMA), late onset, selective neurodegeneration, genetic anticipation, a pathological threshold at which the mutation becomes virulent, and an inverse correlation between CAG repeat length and age at disease onset.