Transthyretin: no association between serum levels or gene variants and schizophrenia

Diversity matters: opportunities in the study of the genetics of psychotic disorders in low- and middle-income countries in Latin America

Lack of diversity regarding genetic and environmental backgrounds weakens the generalization and clinical applicability of research findings on psychotic disorders. Notably, Latin Americans have been generally neglected in genetic studies, comprising less than 2% of genome-wide association study samples. But Latin American populations represent a unique opportunity for research, given the exceptionally high ethnic admixture of this group. Increasing genetic diversity is essential to improve the fine mapping of known regions associated with psychotic disorders, discover novel genetic associations, and replicate studies. Additionally, Latin America is characterized by massive social, political, and economic inequalities, all known risk factors for mental health issues, including psychotic disorders. This article aims to 1) discuss the challenges and advantages of studying Latin America’s particular genetic makeup and environmental context; 2) review previous studies conducted in the region; and 3) describe three Latin American research initiatives in progress: the Neuropsychiatric Genetics of Psychosis in Mexican Populations (NeuroMEX), the Paisa, and the Latin American Network for the Study of Early Psychosis (ANDES) studies.

Serum and cerebrospinal fluid levels of transthyretin in Lewy body disorders with and without dementia

Parkinson's disease (PD) without (non-demented, PDND) and with dementia (PDD), and dementia with Lewy bodies (DLB) are subsumed under the umbrella term Lewy body disorders (LBD). The main component of the underlying pathologic substrate, i.e. Lewy bodies and Lewy neurites, is misfolded alpha-synuclein (Asyn), and--in particular in demented LBD patients--co-occurring misfolded amyloid-beta (Abeta). Lowered blood and cerebrospinal fluid (CSF) levels of transthyretin (TTR)--a clearance protein mainly produced in the liver and, autonomously, in the choroid plexus--are associated with Abeta accumulation in Alzheimer's disease. In addition, a recent study suggests that TTR is involved in Asyn clearance. We measured TTR protein levels in serum and cerebrospinal fluid of 131 LBD patients (77 PDND, 26 PDD, and 28 DLB) and 72 controls, and compared TTR levels with demographic and clinical data as well as neurodegenerative markers in the CSF. Five single nucleotide polymorphisms of the TTR gene which are considered to influence the ability of the protein to carry its ligands were also analyzed. CSF TTR levels were significantly higher in LBD patients compared to controls. Post-hoc analysis demonstrated that this effect was driven by PDND patients. In addition, CSF TTR levels correlated negatively with CSF Abeta(1-42), total tau and phospho-tau levels. Serum TTR levels did not significantly differ among the studied groups. There were no relevant associations between TTR levels and genetic, demographic and clinical data, respectively. These results suggest an involvement of the clearance protein TTR in LBD pathophysiology, and should motivate to elucidate TTR-related mechanisms in LBD in more detail.

Serum proteomic profile of cutaneous malignant melanoma and relation to cancer progression: association to tumor derived alpha-N-acetylgalactosaminidase activity

Currently clinical outcome in melanoma is not predictable by known serum biomarkers. The only reliable tool for the diagnosis of this tumor is the histopathological assay after surgical removing. We used a proteomic approach in order to identify novel non-invasive serum biomarkers of melanoma. Serum proteomic maps showed different patterns in relation to the presence and progression of the tumor in five regions of the map. Differently expressed spots were identified by MALDI-TOF mass spectrometry. Significant increases of expression were found for transthyretin (TTR) and angiotensinogen (AGT) while vitamin D binding protein (DBP) expression was decreased in presence of melanoma. Interestingly, protein expression came back to control values in stages I and II of the disease after 1 month since surgical removal of suspected melanoma. We related the decrease of DBP spot to the impaired immune response of cancer patients. In fact cancer cells release the alpha-N-acetylgalactosaminidase that can deglycosylate DBP thus interfering with the immune cascade response in which DBP is involved, leading to immunosuppression in melanoma patients. Specific enzymatic activity of serum alpha-N-acetylgalactosaminidase was significantly increased in stage III melanoma patients, but not in early stages. This enzymatic assay may provide a non-invasive way of evaluation of melanoma severity.