NMO-IgG predicts the outcome of recurrent optic neuritis

Is neuromyelitis optica associated with human leukocyte antigen?

BACKGROUND

To establish whether or not multiple sclerosis (MS) and neuromyelitis optica (NMO) are different pathological entities, we wondered whether MS patients and NMO patients share the same pattern of human leukocyte antigen (HLA) predisposition.

OBJECTIVE

To study a putative association between susceptibility to NMO and HLA class I or class II loci in Caucasians.

METHODS

A total of 39 unrelated Caucasian patients with NMO and six patients at a high risk of converting to NMO were studied. DNA genotyping of HLA class I and class II loci was assessed and allelic frequencies were reported at a high-resolution level. A case-control study by comparing the allelic distribution in the NMO patients with that of a French Caucasian MS group and a French Caucasian healthy group was carried out.

RESULTS

The frequencies of HLA-DQA1, DQB1, and HLA-DRB1 DR2 alleles in the NMO group were intermediate between the healthy control group and the MS group. The DPB1*0501 allele was not increased in the NMO group compared with the healthy control group. The distribution of HLA-DRB1 allele enabled to distinguish between NMO-IgG-positive patients and healthy controls (P = 0.01). NMO-IgG-negative patients presented an HLA II pattern closer to that of the MS group (P = 0.01).

CONCLUSION

In contrast to the reported results in Asian opticospinal MS, we found no association between the DPB1*0501 allele and NMO in our Caucasian patients. Moreover, we suggest that NMO-IgG-positive patients could represent a distinct NMO group in terms of their genetic susceptibility.

Neuromyelitis optica: diagnosis, pathogenesis, and treatment

Although the co-occurrence of myelitis and optic neuritis that characterizes neuromyelitis optica (NMO) was recognized over a century ago, distinguishing NMO from multiple sclerosis relied solely on clinical criteria until recently. The identification of a biomarker that has high specificity for NMO is clinically useful for distinguishing NMO from multiple sclerosis and identifying patients at high risk for recurrent myelitis and optic neuritis. That fact that the biomarker is an autoantibody that recognizes aquaporin 4 (AQP4), a water channel expressed on astrocyte podocytes, has substantially contributed to the hypothesis that NMO is a humorally mediated autoimmune disease. This review discusses the discovery of the NMO-IgG biomarker, the identification of AQP4 as its target, the clinical applications of these advances, the pathologic implications for the anti-AQP4 antibody, and advances in NMO treatment.

Neuromyelitis optica and multiple sclerosis in sisters

INTRODUCTION

The association of neuromyelitis optica (NMO) and multiple sclerosis (MS) has been reported, but details of the cases were not described. We report two Venezuelan Caucasian sisters with human leukocyte antigen (HLA) typing.

RESULTS

Patient 1 fulfilled McDonald, et al. criteria with HLA A*24; B*07,*15; DRB1*01,*16 (DR2 positive). Patient 2 fulfilled the NMO revised criteria of Wingerchuck, et al. with HLA A*02,*24; B*07,*40; DRB1*04,*08, similar to Canadian aboriginal NMO cases and the Yukpa population from Venezuela.

CONCLUSION

These cases confirmed the coexistence of NMO and MS in sisters, and further studies are needed to understand the genetic linkage between these diseases.

Differential diagnosis of suspected multiple sclerosis: a consensus approach

BACKGROUND AND OBJECTIVES

Diagnosis of multiple sclerosis (MS) requires exclusion of diseases that could better explain the clinical and paraclinical findings. A systematic process for exclusion of alternative diagnoses has not been defined. An International Panel of MS experts developed consensus perspectives on MS differential diagnosis.

METHODS

Using available literature and consensus, we developed guidelines for MS differential diagnosis, focusing on exclusion of potential MS mimics, diagnosis of common initial isolated clinical syndromes, and differentiating between MS and non-MS idiopathic inflammatory demyelinating diseases.

RESULTS

We present recommendations for 1) clinical and paraclinical red flags suggesting alternative diagnoses to MS; 2) more precise definition of "clinically isolated syndromes" (CIS), often the first presentations of MS or its alternatives; 3) algorithms for diagnosis of three common CISs related to MS in the optic nerves, brainstem, and spinal cord; and 4) a classification scheme and diagnosis criteria for idiopathic inflammatory demyelinating disorders of the central nervous system.

CONCLUSIONS

Differential diagnosis leading to MS or alternatives is complex and a strong evidence base is lacking. Consensus-determined guidelines provide a practical path for diagnosis and will be useful for the non-MS specialist neurologist. Recommendations are made for future research to validate and support these guidelines. Guidance on the differential diagnosis process when MS is under consideration will enhance diagnostic accuracy and precision.