Haptoglobin polymorphism and schizophrenia: Genetic variation on chromosome 16

Recently, it was shown that schizophrenia is accompanied by an activation o f the inflammatory response system with signs of an acute phase response, s uch as increased plasma haptoglobin (Hp) concentrations. Hp is characterize d by a molecular variation with three known phenotypes, i.e. Hp 1-1, Hp 2-1 and Hp 2-2. The aim of the present study was to examine Hp phenotypic and genotypic frequencies in schizophrenic patients. Hp phenotyping was carried out in 98 Northwestern Italian schizophrenic patients and the phenotypic a nd genotypic distributions were compared with the distributions established in the Northwestern Italian population. Plasma Hp concentrations were dete rmined by means of a laser nephelometric method. The allele frequency of th e Hp phenotypes in schizophrenia, i.e. Hp 1-1 (9.2%), Hp 2-1 (38.8%) and Hp 2-2 (52.0%), was significantly different from that in the Northwestern Ita lian population, i.e. Hp 1-1 (17.0%), Hp 2-1 (51.3%) and Hp 2-2 (38.5%). Th e frequency of the Hp-2 gene was significantly higher in schizophrenic pati ents (71.7%) as compared with the observed frequency in the Northwestern It alian population (62.5%). The alterations in Hp phenotypic and genotypic di stribution were more pronounced in the schizo-affective, disorganized, undi fferentiated and residual schizophrenic patients than in paranoid schizophr enic patients. More than a third (35.7%) of the schizophrenic patients show ed plasma Hp concentrations which were higher than the upper limits of norm ality. Schizophrenia is accompanied by an altered distribution of the Hp ph enotypes and genotypes, suggesting that genetic variation on chromosome 16 may be associated with schizophrenia (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.