Will genetic polymorphism of tetranucleotide sequences help in the diagnostics of major psychiatric disorders?

Forensic STR Loci and Schizophrenia: An Exploration of Implications for Forensic Applications and Genetic Privacy

BACKGROUND/OBJECTIVES

Short tandem repeat (STR) loci are widely used in forensic genetics for identification and kinship analysis. Traditionally, these loci were selected to avoid medical associations, but recent studies suggest that loci such as TH01 and D16S539 may be linked to psychiatric conditions like schizophrenia. This study explores these potential associations and considers the privacy implications related to disease susceptibility.

METHODS

We analyzed 19 STR loci, including CODIS core loci and additional loci like Penta D and Penta E. Statistical analyses were conducted on a dataset of schizophrenia patients and matched control individuals to assess the relationship between STR polymorphisms and schizophrenia risk.

RESULTS

No significant associations were found between the 19 analyzed loci and schizophrenia in this dataset. While initial analyses revealed minor allele frequency differences at the D3S1358, D13S317, and TPOX loci between the schizophrenia and control groups, these differences did not retain statistical significance following Bonferroni correction (corrected p < 0.0026 for all loci).

CONCLUSIONS

Although no significant associations were found between STR loci and schizophrenia, this study highlights the importance of considering the potential for forensic DNA data to reveal health-related information. As forensic DNA databases continue to expand, there is a growing need to reassess ethical and legal guidelines to ensure the protection of individual privacy. Future research should continue exploring these genetic associations with larger, more diverse samples to further understand their implications.

Positive Association of TEAD1 With Schizophrenia in a Northeast Chinese Han Population

OBJECTIVE

Schizophrenia is a complex and devastating psychiatric disorder with a strong genetic background. However, much uncertainty still exists about the role of genetic susceptibility in the pathophysiology of schizophrenia. TEA domain transcription factor 1 (TEAD1) is a transcription factor associated with neurodevelopment and has modulating effects on various nervous system diseases. In the current study, we performed a case-control association study in a Northeast Chinese Han population to explore the characteristics of pathogenic TEAD1 polymorphisms and potential association with schizophrenia.

METHODS

We recruited a total of 721 schizophrenia patients and 1,195 healthy controls in this study. The 9 single nucleotide polymorphisms (SNPs) in the gene region of TEAD1 were selected and genotyped.

RESULTS

The genetic association analyses showed that five SNPs (rs12289262, rs6485989, rs4415740, rs7113256, and rs1866709) were significantly different between schizophrenia patients and healthy controls in allele or/and genotype frequencies. After Bonferroni correction, the association of three SNPs (rs4415740, rs7113256, and rs1866709) with schizophrenia were still evident. Haplotype analysis revealed that two strong linkage disequilibrium blocks (rs6485989-rs4415740-rs7113256 and rs16911710-rs12364619-rs1866709) were globally associated with schizophrenia. Four haplotypes (C-C-C and T-T-T, rs6485989-rs4415740-rs7113256; G-T-A and G-T-G, rs16911710-rs12364619-rs1866709) were significantly different between schizophrenia patients and healthy controls.

CONCLUSION

The current findings indicated that the human TEAD1 gene has a genetic association with schizophrenia in the Chinese Han population and may act as a susceptibility gene for schizophrenia.

Forensic Autosomal Short Tandem Repeats and Their Potential Association With Phenotype

Forensic DNA profiling utilizes autosomal short tandem repeat (STR) markers to establish identity of missing persons, confirm familial relations, and link persons of interest to crime scenes. It is a widely accepted notion that genetic markers used in forensic applications are not predictive of phenotype. At present, there has been no demonstration of forensic STR variants directly causing or predicting disease. Such a demonstration would have many legal and ethical implications. For example, is there a duty to inform a DNA donor if a medical condition is discovered during routine analysis of their sample? In this review, we evaluate the possibility that forensic STRs could provide information beyond mere identity. An extensive search of the literature returned 107 articles associating a forensic STR with a trait. A total of 57 of these studies met our inclusion criteria: a reported link between a STR-inclusive gene and a phenotype and a statistical analysis reporting a p-value less than 0.05. A total of 50 unique traits were associated with the 24 markers included in the 57 studies. TH01 had the greatest number of associations with 27 traits reportedly linked to 40 different genotypes. Five of the articles associated TH01 with schizophrenia. None of the associations found were independently causative or predictive of disease. Regardless, the likelihood of identifying significant associations is increasing as the function of non-coding STRs in gene expression is steadily revealed. It is recommended that regular reviews take place in order to remain aware of future studies that identify a functional role for any forensic STRs.

Characterization of the standard and recommended CODIS markers

As U.S. courts grapple with constitutional challenges to DNA identification applications, judges are resting legal decisions on the fingerprint analogy, questioning whether the information from a DNA profile could, in light of scientific advances, reveal biomedically relevant information. While CODIS loci were selected largely because they lack phenotypic associations, how this criterion was assessed is unclear. To clarify their phenotypic relevance, we describe the standard and recommended CODIS markers within the context of what is known currently about the genome. We characterize the genomic regions and phenotypic associations of the 24 standard and suggested CODIS markers. None of the markers are within exons, although 12 are intragenic. No CODIS genotypes are associated with known phenotypes. This study provides clarification of the genomic significance of the key identification markers and supports--independent of the forensic scientific community--that the CODIS profiles provide identification but not sensitive or biomedically relevant information.

Association of TH01 with human longevity revisited

The gene tyrosine hydroxylase 1 (TH01) has been suggested as a candidate for human longevity. A previous study has shown an association between longevity and specific alleles of the TH01 short tandem repeat (STR) polymorphism in an Italian population. This STR locus is also widely used in forensic genetics. If the TH01-longevity association could be confirmed in independent samples, this finding would have important ramifications for the use of this polymorphism in a forensic context. In the present study, we sought to replicate the previous association result by investigating 471 long-lived individuals (96-110 years) and 462 younger controls (19-75 years) from Germany. In the analyzed samples, the association between TH01 and longevity was not replicated. However, the obtained TH01 allele frequencies were consistent with published data. We observed considerable differences in the allele distribution between Germans and Italians, in particular with regard to allele 9.3, which displayed a previously undetected decreasing West-East and North-South cline across Europe. The discrepant TH01-longevity association results in Germans and Italians could therefore be due to population-specific effects. This finding highlights the need to take into consideration population genetic data when dealing with association studies.

Tyrosine hydroxylase, interleukin-1beta and tumor necrosis factor-alpha are overexpressed in peripheral blood mononuclear cells from schizophrenia patients as determined by semi-quantitative analysis

The aim of this study is to profile the peripheral biomarkers (tyrosine hydroxylase, TH; interleukin-1beta, IL-1beta; and tumor necrosis factor-alpha, TNF-alpha) for schizophrenia and explore their relations with clinical symptoms. Thirty-nine patients with schizophrenia were evaluated using the Positive and Negative Syndrome Scale (PANSS), and 25 siblings and 30 normal healthy subjects were used as controls. The mRNA expression levels of TH, IL-1beta and TNF-alpha in peripheral blood mononuclear cells, as determined with semi-quantitative reverse transcription-polymerase chain reaction, were all significantly increased in both patients (3-fold) and siblings (2-fold) as compared with normal control. Both IL-1beta and TNF-alpha were significantly correlated with scores on the general psychopathology subscale of the PANSS. A significant positive correlation between IL-1beta and TH expression was found in both sibling and normal controls, but not in patients, while a positive correlation between IL-1beta and TNF-alpha was significant in all the groups. These results suggest that TH, IL-1beta and TNF-alpha are overexpressed in the peripheral blood mononuclear cells of schizophrenia patients, perhaps due to the hereditary factors. IL-1beta and TNF-alpha may influence the symptoms of schizophrenia in the cognition dysfunction and anxiety/depression domains of the PANSS.