Gc serum groups and schizophrenia

Common variants of the vitamin D binding protein gene and adverse health outcomes

The vitamin D binding protein (DBP) is the major plasma carrier for vitamin D and its metabolites, but it is also an actin scavenger, and is the precursor to the immunomodulatory protein, Gc-MAF. Two missense variants of the DBP gene - rs7041 encoding Asp432Glu and rs4588 encoding Thr436Lys - change the amino acid sequence and alter the protein function. They are common enough to generate population-wide constitutive differences in vitamin D status, based on assay of the serum metabolite, 25-hydroxyvitamin D (25OHD). Whether these variants also influence the role of vitamin D in an immunologic milieu is not known. However, the issue is relevant, given the immunomodulatory effects of DBP and the role of protracted innate immune-related inflammation in response to tissue injury or repeated infection. Indeed, DBP and vitamin D may jointly or independently contribute to a variety of adverse health outcomes unrelated to classical notions of their function in bone and mineral metabolism. This review summarizes the reports to date of associations between DBP variants, and various chronic and infectious diseases. The available information leads us to conclude that DBP variants are a significant and common genetic factor in some common disorders, and therefore, are worthy of closer attention. In view of the heightened interest in vitamin D as a public health target, well-designed studies that look simultaneously at vitamin D and its carrier in relation to genotypes and adverse health outcome should be encouraged.

Serum protein markers in Chinese schizophrenics--haptoglobin types and transferrin and group-specific component subtypes

Four hundred and thirty-nine Chinese schizophrenic male patients were investigated for the distribution of haptoglobin types; transferrin and group-specific component subtypes. The allelic frequencies of these three polymorphisms in the patient group were compared with those in healthy controls from published series. An excess of Gc2 over Gc1 (chi 2(1) 4.1; P less than 0.05) as well as a lack of Gc1S (chi 2(1) 15.3; P less than 0.001) was observed in schizophrenia. The relative risks of Gc1F, Gc1S and Gc2 have been estimated as 1.12, 0.76 and 1.15, respectively. It appears from this study that the presence of Gc2 renders individuals susceptible while Gc1S offers protection for schizophrenia. No such association was found for the haptoglobin or transferrin polymorphisms.

Group-specific component (Gc) subtypes and schizophrenia

Two hundred and fifteen schizophrenic patients (108 males and 107 females) in north-east England have been investigated for Gc types and subtypes and compared with the frequencies in first-degree relatives and controls. Böök et al. (1978) described Gc2 allele association with schizophrenia. No such association was found with the Gc2 allele in the present study although there is a tendency towards an increased frequency in females. In subtype allele frequencies the female patients showed a significant reduction of Gc1S allele. The results suggest a difference in susceptibility associated with the Gc locus in patients of different sexes.