Association study of schizophrenia and the dopamine D3 receptor gene locus in two independent samples

Isolation of a novel potassium channel gene hSKCa3 containing a polymorphic CAG repeat: a candidate for schizophrenia and bipolar disorder?

“…All patients and controls described here have previously been used in other published studies. 13,18 European patients: Unrelated patients of French or Alsatian ancestry meeting DSM-IV criteria for schizophrenia or BPD-I were genotyped; Mediterranean Caucasians, Asians, and Africans were excluded. Patients were examined with an unstructured clinical interview and also with a structured clinical interview (SADSLifetime Version, 35 final diagnoses being made by a consensus of two psychiatrists.…”

“…Using a microsatellite assay, we genotyped the second repeat in 319 chromosomes in unrelated Caucasian adult controls from Europe and USA. 13,18 Alleles ranged in length from 12 to 28 CAG repeats, the modal length being 19 repeats for both populations ( Figure 2). We also sampled 44 unselected Caucasian neonates whose allele distribution and modal repeat length (19 repeats) was indistinguishable from adult controls (data not shown).…”

“…We have used two Caucasian populations which have previously been used in published studies. 13,18 These cohorts were analyzed independently in Europe and in the USA, to determine if the presence of longer CAG repeats in hSKCa3 is associated with neuropsychiatric disorders. Caucasian patients with schizophrenia were compared with ethnically matched, unrelated, screened adult controls.…”

Dopamine D3 receptor gene variants and substance abuse in schizophrenia

“…These results are in agreement with two previous studies, 17,20 although not always replicated. 18,[21][22][23][24][25][26] The various criteria used to define treatment efficacy in these previous reports could at least partly explain the discrepancies. Definition of treatment response can rely on persistence of positive or negative symptoms, percentage of improvement on symptomatic scales, ability for reinsertion and/or election for clozapine therapy; leading to distinct clinical subgroups, whose relevance with regard to underlying physiopathological processes is questionable.…”

Examination of new and reported data of the DRD3/MscI polymorphism: no support for the proposed association with schizophrenia

“…10 Extending the sample size, the association was found to be most marked in schizophrenic males, those with family history and in good responders to antipsychotic drugs. 11,12 In independent samples of patients and controls, Nimgaonkar et al 13,14 suggested an association with allele 1 and Shaikh et al 15 likewise showed an association with allele 1. In contrast, Kennedy et al 16 showed a higher frequency of allele 2 and genotype 2-2 in their patients and most recently Ebstein et al 17 found the allele 2 and the genotype 2-2 to be significantly associated with the disease in a combined sample of Italian, Ashkenazi and non-Ashkenazi Jews.…”