Epilepsy comprises several syndromes, amongst the most common being mesial temporal lobe epilepsy with hippocampal sclerosis. Seizures in mesial temporal lobe epilepsy with hippocampal sclerosis are typically drug-resistant, and mesial temporal lobe epilepsy with hippocampal sclerosis is frequently associated with important co-morbidities, mandating the search for better understanding and treatment. The cause of mesial temporal lobe epilepsy with hippocampal sclerosis is unknown, but there is an association with childhood febrile seizures. Several rarer epilepsies featuring febrile seizures are caused by mutations in SCN1A, which encodes a brain-expressed sodium channel subunit targeted by many anti-epileptic drugs. We undertook a genome-wide association study in 1018 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 7552 control subjects, with validation in an independent sample set comprising 959 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 3591 control subjects. To dissect out variants related to a history of febrile seizures, we tested cases with mesial temporal lobe epilepsy with hippocampal sclerosis with (overall n = 757) and without (overall n = 803) a history of febrile seizures. Meta-analysis revealed a genome-wide significant association for mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures at the sodium channel gene cluster on chromosome 2q24.3 [rs7587026, within an intron of the SCN1A gene, P = 3.36 × 10⁻⁹, odds ratio (A) = 1.42, 95% confidence interval: 1.26–1.59]. In a cohort of 172 individuals with febrile seizures, who did not develop epilepsy during prospective follow-up to age 13 years, and 6456 controls, no association was found for rs7587026 and febrile seizures. These findings suggest SCN1A involvement in a common epilepsy syndrome, give new direction to biological understanding of mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures, and open avenues for investigation of prognostic factors and possible prevention of epilepsy in some children with febrile seizures.

Autoimmune diseases (AIDs) are characterized by a multifactorial aetiology and a complex genetic background, with the MHC region playing a major role. We genotyped for HLA-DRB1 locus 1228 patients with AIDs-213 with Systemic Lupus Erythematosus (SLE), 166 with Psoriasis or Psoriatic Arthritis (Ps + PsA), 153 with Rheumatoid Arthritis (RA), 67 with Systemic Sclerosis (SSc), 536 with Multiple Sclerosis (MS), and 93 with Myasthenia Gravis (MG) and 282 unrelated controls. We confirmed previously established associations of HLA-DRB115 (OR = 2.17) and HLA-DRB103 (OR = 1.81) alleles with MS, HLA-DRB103 with SLE (OR = 2.49), HLA-DRB101 (OR = 1.79) and HLA-DRB104 (OR = 2.81) with RA, HLA-DRB107 with Ps + PsA (OR = 1.79), HLA-DRB101 (OR = 2.28) and HLA-DRB108 (OR = 3.01) with SSc, and HLA-DRB103 with MG (OR = 2.98). We further observed a consistent negative association of HLA-DRB113 allele with SLE, Ps + PsA, RA, and SSc (18.3%, 19.3%, 16.3%, and 11.9%, resp., versus 29.8% in controls). HLA-DRB113 frequency in the AIDs group was 20.0% (OR = 0.58). Although different alleles were associated with particular AIDs, the same allele, HLA-DRB113, was underrepresented in all of the six diseases analysed. This observation suggests that this allele may confer protection for AIDs, particularly for systemic and rheumatic disease. The protective effect of HLA-DRB113 could be explained by a more proficient antigen presentation by these molecules, favouring efficient clonal deletion during thymic selection.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease of unknown origin, in which both genetic and environmental factors are involved. One such environmental factor is vitamin D, a vital hormone that plays a specific function in the immune system homeostasis, acting through a nuclear receptor (VDR) expressed in all immune cells. Several polymorphisms of the gene that encodes this receptor have been described. Though inconsistently, these polymorphisms have been associated with clinical manifestations and SLE development. The aim of this study was to determine the possible association between VDR gene polymorphisms (BsmI, ApaI, TaqI e FokI) and SLE susceptibility and severity, in a cohort of lupus patients from the north of Portugal. A total of 170 patients (F = 155, M = 15; age = 45 ± 13.4 years) with SLE (diagnosed according the American College of Rheumatology criteria) with at least five years of disease evolution and followed in the Autoimmune Disease Clinical Immunology Unit of Centro Hospitalar do Porto were studied. Patients and 192 ethnicity-matched controls were genotyped for BsmI (rs1544410), ApaI (rs7975232), TaqI (rs731236) and FokI (rs2228570) polymorphisms by TaqMan allelic discrimination assay. Disease severity was assessed by SLICC damage score, number of affected organs, number of severe flares and pharmacological history. SLE patients with the CT genotype of FokI polymorphism have a higher SLICC value (p = 0.031). The same result was observed for the group of patients with the TT genotype of TaqI polymorphism (p = 0.046). No differences were observed in VDR genotype between patients and controls. Also, we observed that the other clinical features analysed were not influenced by VDR polymorphisms. Our study confirms a possible role of VDR gene polymorphisms in SLE. A positive association was found between VDR polymorphisms and SLE severity (chronic damage). The presence of CT genotype of FokI and TT genotype of TaqI seems to confer a worse prognosis and may constitute a risk factor for higher long-term cumulative damage in SLE patients.