BERLIN – In children with an incident acquired demyelinating episode, the presence of antibodies against myelin oligodendrocyte glycoprotein (MOG) weighs against an eventual diagnosis of multiple sclerosis, especially if the child is younger than 11 years.
Dr. Giulia Fadda
“Anti-MOG antibodies are present in about 30% of children with acquired demyelinating syndromes,” Giulia Fadda, MD, said at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis. “About 80% experience a monophasic disease course.”
The antibodies are found in almost all children who have a relapsing non-MS demyelinating disease, said Dr. Fadda, who is a postdoctoral research fellow at the University of Pennsylvania, Philadelphia. But when the antibodies are present in children with an MS diagnosis, they identify a very specific subset with atypical clinical and imaging features.
The large prospective Canadian Pediatric Demyelinating Disease Study provided the sample for the study she presented at ECTRIMS. Children are recruited into the study soon after a first demyelinating event, and they are followed clinically, serologically, and with regular brain MRI.
The cohort in Dr. Fadda’s study comprised 275 children who were a mean of about 11 years old at symptom onset. The mean clinical follow-up was 6.7 years; the mean serologic follow-up, 4 years, and the mean imaging follow-up, 3.5 years. The study examined 1,368 serum samples and 1,459 MRI scans.
Overall, 32% of the children were positive for anti-MOG antibodies. Positivity was not associated with sex, but children with antibodies were significantly younger than those without (7 vs. 12 years). In fact, 77% of anti-MOG–positive children were younger than 11 years; just 15% of older children were positive for the antibodies.
Anti-MOG positivity was also associated with certain clinical phenotypes. Among positive children, 40% presented with optic neuritis, 37% with acute disseminated encephalomyelitis, and 14% with transverse myelitis; the rest had other phenotypes. Optic neuritis was significantly less common among antibody-negative patients (22%), as was encephalomyelitis (17%). Transverse myelitis was significantly more common (31%).
The analysis of MRI scans was stratified according to age younger than 11 years and 11 years and older. “The first thing we noticed among the younger MOG-positive children is that they had a high number of lesions, which were more commonly ill-defined, diffuse, and bilateral,” Dr. Fadda said. “Almost all the brain areas were affected, with a slight preponderance of thalamic and juxtacortical lesions. Among the MOG-negative children, lesions were more often perpendicular to the major axis of the corpus callosum.”
Among the older MOG antibody–positive children, the diffuse pattern was rarer, and the lesions were frequently cerebellar. “But by far, the features that best differentiated positivity from negativity were black holes and enhancing lesions, which we saw in a high proportion of children without the antibodies” at 73% and 49%, respectively.
Over a mean imaging follow-up period of 4 years, lesions were more likely to resolve completely in antibody-positive children than in those without antibodies (50% vs. 21%). Serologically, children who were MOG-antibody negative at baseline were likely to stay that way, with 99% remaining seronegative. Positive children, on the other hand, were significantly more likely to change serologic status, with 56% turning negative and 8% serologically fluctuating over the follow-up period; only 36% remained persistently seropositive. Persistent positive status was significantly associated with younger age (7 vs. 9 years) and an optic neuritis presentation (62% vs. 27%).
Most children (81%) who were antibody positive at baseline experienced no relapses. Among the 16 children who did experience a clinical relapse, the mean time to a second event was about 1 year. Nine of these children stayed persistently positive, while five seroconverted and two had fluctuating status.
Of the 60 antibody-positive children who had a monophasic course, 23 were persistently positive, 34 seroconverted, and 3 had fluctuating serology.
Eventually, 54 children received an MS diagnosis. Of these, 83% were antibody negative at baseline. Ten children received a diagnosis of a relapsing non-MS demyelinating disorder; of these, 91% were antibody positive at baseline.
Dr. Fadda disclosed relationships with Atara Biotherapeutic and Sanofi-Genzyme.
SOURCE: Waters P et al. Mult Scler. 2018;24(S2):29-30, Abstract 65.