The immunogenetics of multiple sclerosis. The frequency of HLA-alleles class 1 and 2 is lower in Southern Brazil than in the European population

Bioinformatics and system biology approaches to identify pathophysiological impact of COVID-19 to the progression and severity of neurological diseases

The Coronavirus Disease 2019 (COVID-19) still tends to propagate and increase the occurrence of COVID-19 across the globe. The clinical and epidemiological analyses indicate the link between COVID-19 and Neurological Diseases (NDs) that drive the progression and severity of NDs. Elucidating why some patients with COVID-19 influence the progression of NDs and patients with NDs who are diagnosed with COVID-19 are becoming increasingly sick, although others are not is unclear. In this research, we investigated how COVID-19 and ND interact and the impact of COVID-19 on the severity of NDs by performing transcriptomic analyses of COVID-19 and NDs samples by developing the pipeline of bioinformatics and network-based approaches. The transcriptomic study identified the contributing genes which are then filtered with cell signaling pathway, gene ontology, protein-protein interactions, transcription factor, and microRNA analysis. Identifying hub-proteins using protein-protein interactions leads to the identification of a therapeutic strategy. Additionally, the incorporation of comorbidity interactions score enhances the identification beyond simply detecting novel biological mechanisms involved in the pathophysiology of COVID-19 and its NDs comorbidities. By computing the semantic similarity between COVID-19 and each of the ND, we have found gene-based maximum semantic score between COVID-19 and Parkinson's disease, the minimum semantic score between COVID-19 and Multiple sclerosis. Similarly, we have found gene ontology-based maximum semantic score between COVID-19 and Huntington disease, minimum semantic score between COVID-19 and Epilepsy disease. Finally, we validated our findings using gold-standard databases and literature searches to determine which genes and pathways had previously been associated with COVID-19 and NDs.

HLA diversity in Brazil

Brazil is the fifth largest country in the world in area and the fifth most populous. The Brazilian voluntary Bone Marrow Donor Registry is the third largest in terms of number of donors in the world, being a valuable source of HLA genetics to characterize the donor population of Brazil as well. The genetic background of the Brazilian population is quite heterogeneous, resulting from 5 centuries of admixture among Native Americans, Europeans and Africans, making the Brazilian population unique in terms of genetic ancestry. The unique characteristics of populations in different Brazilian regions make them an exciting focus for genetic diversity studies. Studies on HLA genetic diversity of Brazilian populations have been conducted since the late 1980s and, in this review, we highlight the main findings from studies carried out in Brazil based on classical HLA. In addition, we calculated the genetic distance from the molecular data of the studies included in this review in order to have a broader view of the HLA diversity in Brazilian populations. We emphasize that characterization of HLA diversity is not only important for transplantation programs, but can shed a light on ancestry, history and other demographic patterns with or without association with autoimmune disease.

Familial multiple sclerosis in a Brazilian sample: Is HLA-DR15 involved in susceptibility to the disease?

BACKGROUND

The HLA-DR15 extended haplotype HLA-DRB1*15:01-DQA1*01:02-DQB1*06:02 comprises the strongest genetic risk factor for multiple sclerosis (MS). The aim of this work was to investigate whether HLA-DR15 alleles were significantly associated with the susceptibility to MS familial forms (MSf) in an admixed Brazilian population.

METHODS

Association analyses between DR15 and the clinical and demographic variables were made.

RESULTS

We have genotyped 25 familial cases. The DR15 was detected in 11/25 (44%) of them and in none of controls (P < .00001). DR15 was significantly associated to a foreign ancestor background (P = .029) and later age of onset (P = .018).

The genetics of multiple sclerosis in Latin America

Background

In today’s globalised world, the heterogeneity of diseases such as multiple sclerosis has been studied since it has been suggested that ethnic differences, in conjunction with geographical and environmental factors, influence its incidence and prevalence.

Aim

Based on this, an attempt has been made to identify the genetic factors that may confer risk or protection, not only for developing multiple sclerosis but also for determining the course of its evolution.

Results

In Latin America we have some data about this, which have been replicated in different populations in the entire region, with very different results compared with other regions, which could explain not only the different frequencies in some populations, such as Caucasians, but also the course of the disease and the response to actual treatments. However, in addition to these findings, other associated epigenetic mechanisms have also been found in our populations, such as levels of vitamin D, parasitic diseases, and indigenous populations. Therefore, the study of epigenetics plays a crucial role in understanding the physiopathology of multiple sclerosis. It must be studied in each population, especially in Latin America, due to its broad heterogeneity.

Conclusion

It is very important to understand not only the genetic and external factors with these very specific effects in multiple sclerosis patients, but also the way they interact and are able to explain the frequency and some specific phenotypes of the disease in our populations besides the posibility to be a very specific treatment target.