Sibling disability risk at onset and during disease progression in familial multiple sclerosis

Genetics of multiple sclerosis: lessons from polygenicity

Large-scale mapping studies have identified 236 independent genetic variants associated with an increased risk of multiple sclerosis. However, none of these variants are found exclusively in patients with multiple sclerosis. They are located throughout the genome, including 32 independent variants in the MHC and one on the X chromosome. Most variants are non-coding and seem to act through cell-specific effects on gene expression and splicing. The likely functions of these variants implicate both adaptive and innate immune cells in the pathogenesis of multiple sclerosis, provide pivotal biological insight into the causes and mechanisms of multiple sclerosis, and some of the variants implicated in multiple sclerosis also mediate risk of other autoimmune and inflammatory diseases. Genetics offers an approach to showing causality for environmental factors, through Mendelian randomisation. No single variant is necessary or sufficient to cause multiple sclerosis; instead, each increases total risk in an additive manner. This combined contribution from many genetic factors to disease risk, or polygenicity, has important consequences for how we interpret the epidemiology of multiple sclerosis and how we counsel patients on risk and prognosis. Ongoing efforts are focused on increasing cohort sizes, increasing diversity and detailed characterisation of study populations, and translating these associations into an understanding of the biology of multiple sclerosis.

Familial forms of multiple sclerosis and neuromyelitis optica at an MS center in Rio de Janeiro State, Brazil

OBJECTIVE

To describe familial forms of demyelinating diseases from an MS referral center in Río de Janeiro State, Brazil.

METHODS

A descriptive, cross-sectional study was done to identify familial IIDD cases in Hospital da Lagoa, a public hospital where 75% of patients with IIDD who live in Rio de Janeiro state, located in the Southeast region of Brazil, are referred. The diagnoses of all consecutive patients followed in 2011 were reviewed to apply new diagnostic criteria (Wingerchuk et al., 2008). The diagnosis of IIDD was confirmed based on clinical history, neurological examination, MRI of the skull and spinal cord, CSF analysis and investigation of IgG NMO antibodies. The cases that had at least one other relative with IIDD were selected for the study.

RESULTS

Familial forms were found only in the multiple sclerosis (MS) and neuromyelitis optica syndrome (NMOSD) categories. 23 MS families were identified, 60.86% with first degree kinship. It has a Caucasian preponderance, 90% of whom were white. The frequency of early onset was 15% and 20% of the MSf cases have progressive primary course.

CONCLUSION

The frequency of familial cases of IIDD was 6.12% among MS patients and 2.8% in NMO spectrum syndromes.

Genetic determinants of risk and progression in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that represents a primary cause of neurological disability in the young adult population. Converging evidence supports the importance of genetic determinants for MS etiology. However, with the exception of the major histocompatibility complex, their nature has been elusive for more than 20 years. In the last decade, the advent of large genome-wide association studies has significantly improved our understanding of the disease, leading to the golden era of MS genetic research. To date more than 110 genetic variants have been firmly associated to an increased risk of developing MS. A large part of these variants tag genes involved in the regulation of immune response and several of them are shared with other autoimmune diseases, suggesting a common etiological root for this class of disorders. Despite the impressive body of data obtained in the last years, we are still far from fully decoding MS genetic complexity. For example, we ignore how these genetic factors interact with each other and with the environment. Thus, the biggest challenge for the next era of MS research will consist in identifying and characterizing the molecular mechanisms and the cellular pathways in which these risk variants play a role.

[Prognostic and predictively relevant factors for multiple sclerosis]

The immunotherapy of multiple sclerosis (MS) is currently one of the most dynamic fields in clinical neurology. The comprehensive number of well-established and new innovative treatment options are a challenge for an intensive preoccupation with the differential indications and an activity-driven treatment control. In this context this review summarizes the known predictors of the natural course of MS and gives a review of challenges to be expected in association with predictors of treatment control.