Group-specific component (Gc) subtypes and schizophrenia

Vitamin D binding protein in psychiatric and neurological disorders: Implications for diagnosis and treatment

Vitamin D binding protein (VDBP) serves as a key transporter protein responsible for binding and delivering vitamin D and its metabolites to target organs. VDBP plays a crucial part in the inflammatory reaction following tissue damage and is engaged in actin degradation. Recent research has shed light on its potential role in various diseases, leading to a growing interest in understanding the implications of VDBP in psychiatric and neurological disorders. The purpose of this review was to provide a summary of the existing understanding regarding the involvement of VDBP in neurological and psychiatric disorders. By examining the intricate interplay between VDBP and these disorders, this review contributes to a deeper understanding of underlying mechanisms and potential therapeutic avenues. Insights gained from the study of VDBP could pave the way for novel strategies in the diagnosis, prognosis, and treatment of psychiatric and neurological disorders.

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.

Schizophrenia and rheumatoid arthritis: a review

Fourteen epidemiologic studies of the relationship of rheumatoid arthritis to schizophrenia have been conducted between 1934 and 1985. Twelve of the studies report a lower-than-expected rate of rheumatoid arthritis in populations of schizophrenics. Methodologic weaknesses in the studies are assessed. Nutritional, hormonal, psychosocial, genetic, and immunologic data and theories are briefly reviewed which might explain the epidemiologic results. There is sufficient evidence for the negative association between the two disorders to justify further research.

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.

Genetics of schizophrenia: II. Vulnerability traits and gene markers

The author reviews research strategies for identifying biological vulnerability traits and gene markers. The application of these methods to schizophrenia are discussed. He concludes that, based on the available evidence, none of the proposed biological traits qualifies as a major factor in the genetic susceptibility to schizophrenia. Some of these traits (such as attentional, neurophysiological, and brain morphology measures) appear promising, but the data are inadequate to arrive at a firm conclusion. Studies with gene markers have not produced consistent results. The author presents the methodological issues that concern this area of research and offers recommendations for future studies.