Background: Human Leucocyte Antigens (HLA) represent the genetic loci most strongly linked to Multiple Sclerosis (MS). Apart from HLA-DR and HLA–DQ, HLA-DP alleles have been previously studied regarding their role in MS pathogenesis, but to a much lesser extent. Our objective was to investigate the risk/resistance influence of HLA-DPB1 alleles in Hellenic patients with early- and adult-onset MS (EOMS/AOMS), and possible associations with the HLA-DRB1*15:01 risk allele. Methods: One hundred MS-patients (28 EOMS, 72 AOMS) fulfilling the McDonald-2010 criteria were enrolled. HLA genotyping was performed with standard low-resolution Sequence-Specific Oligonucleotide techniques. Demographics, clinical and laboratory data were statistically processed using well-defined parametric and nonparametric methods and the SPSSv22.0 software. Results: No significant HLA-DPB1 differences were found between EOMS and AOMS patients for 23 distinct HLA-DPB1 and 12 HLA-DRB1 alleles. The HLA-DPB1*03 allele frequency was found to be significantly increased, and the HLA-DPB1*02 allele frequency significantly decreased, in AOMS patients compared to controls. The HLA-DPB1*04 allele was to be found significantly decreased in AOMS and EOMS patients compared to controls. Conclusions: Our study supports the previously reported risk susceptibility role of the HLA-DPB1*03 allele in AOMS among Caucasians. Additionally, we report for the first time a protective role of the HLA-DPB1*04 allele among Hellenic patients with both EOMS and AOMS.

Multiple sclerosis (MS) and its various comorbidities that may be observed are of great interest due to the complexity of MS pathophysiology and all of the immunological changes that follow. The incidence of cancer in MS has been investigated for several years, as not only does it affect ongoing therapeutical decisions, but also, certain disease-modifying treatments (DMTs) may increase the risk of tumorigenesis. For the first time, we present a case of a female patient with pediatric-onset MS (POMS) and multiple endocrine neoplasia 2B (MEN2B) and analyze the immunological impact of these diseases on the therapeutical choice, under the umbrella of her COVID-19 infection and the SARS-CoV-2 pandemic as a whole. We also review the existing literature regarding the immunogenetic and immunological correlations between these two extremely rare diseases and discuss the most suitable treatment for our case, which seems to be an anti-CD20 agent due to a better outcome in putative MS worsening and tumor progression, when killer immunoglobulin-like receptors’ (KIR) expression is reduced in natural killer (NK) cells. We also broaden our concerns on this comorbidity issue, at the same time focusing on the future research needed in this unexplored field of the comorbidity of MS and cancers.