Table 1.

Summary of the available data regarding the distribution of HLA alleles and MRI findings for the four major pediatric demyelinating clinical entities, as they have emerged under the scope of the latest genetic, antibody, and imaging markers [12, 50–71, 74, 98–101, 110–117].

	Clinically definite MS	AQP4 (+) NMOSD	MOG antibody associated disorders	ADEM Ab(-)
HLA allele	HLA-DRB1∗1501 (Caucasian) HLA-DRB1∗0401 (Caucasian) HLA-DRB3∗02 & HLA-DRB1∗13 & HLA-DQB1∗03 (Korean)	HLA-DRB1∗03 (adult Caucasian) HLA-DRB1∗0501 (adult Japanese)	HLA-DRB1∗0401 (?)	HLA-DRB1∗01 & HLA-DRB1∗017 (Russian) HLA-DRB1∗1501 & HLA-DRB5∗0101 (Korean) HLA-DQB1∗0602& HLA-DRB1∗1501 & HLA-DRB1∗1503 (Brazilian) HLA-DRB1∗16 & HLA-DQB1∗05 (Caucasian adult)
MRI	Ovoid, well-defined lesions in at least two regions (periventricular, cortical, or juxtacortical U-fibers, infratentorial and spinal cord), Dawson fingers and black holes in T1, ring pattern of Gd enhancement	(1) Lesions (usually small & localized) involving the dorsal medulla and the periependymal surface of the ventricles; large, confluent, unilateral, or bilateral subcortical/deep white matter lesions and long lesions (>1/2 length) of the corpus callosum (2) LETM with probable rostral extension of the lesion into the brainstem (3) Unilateral or bilateral increased T2 signal or Gd enhancement within optic nerve or optic chiasm, >1/2 the distance from orbit to chiasm	(1) Longitudinally extensive spinal cord lesion (≥3 VS, contiguous) on MRI (so-called LETM) (2) Longitudinally extensive spinal cord atrophy (≥3 VS, contiguous) on MRI in patients with a history compatible with acute myelitis (3) Conus medullaris lesions, especially if present at onset (4) Longitudinally extensive optic nerve lesion (e.g., >1/2 of the length of the pre-chiasmal optic nerve, T2 or T1/Gd) (5) Perioptic Gd enhancement during acute ON (6) Normal supratentorial MRI in patients with acute ON, myelitis and/or brainstem encephalitis (7) Brain MRI abnormal but no lesion adjacent to a lateral ventricle that is ovoid/round or associated with an inferior temporal lobe lesion and no Dawson's finger-type or juxtacortical U fiber lesion (Matthews-Jurynczyk criteria) (8) Large, confluent T2 brain lesions suggestive of ADEM	Large, diffuse, poorly demarcated (>1 to 2 cm) lesions involving predominantly the cerebral white matter; deep gray matter lesions; T1-hypointense lesions in the white matter are rare

MS: multiple sclerosis, ADEM: acute disseminated encephalomyelitis, NMOSD: neuromyelitis optica spectrum disorders, MOG: myelin oligodendrocyte glycoprotein, LETM: longitudinally extensive transverse myelitis, Gd: gadolinium, VS: vertebral segments.