High genetic heterogeneity of leukodystrophies in Iranian children: the first report of Iranian Leukodystrophy Registry.

Leukodystrophies (LDs) are a heterogeneous group of progressive neurological disorders and characterized by primary involvement of white matter of the central nervous system (CNS). This is the first report of the Iranian LD Registry database to describe the clinical, radiological, and genomic data of Persian patients with leukodystrophies. From 2016 to 2019, patients suspicious of LDs were examined followed by a brain magnetic resonance imaging (MRI). A single gene testing or whole-exome sequencing (WES) was used depending on the neuroradiologic phenotypes. In a few cases, the diagnosis was made by metabolic studies. Based on the MRI pattern, diagnosed patients were divided into cohorts A (hypomyelinating LDs) versus cohort B (Other LDs). The most recent LD classification was utilized for classification of diagnosed patients. For novel variants, in silico analyses were performed to verify their pathogenicity. Out of 680 registered patients, 342 completed the diagnostic evaluations. In total, 245 patients met a diagnosis which in turn 24.5% were categorized in cohort A and the remaining in cohort B. Genetic tests revealed causal variants in 228 patients consisting of 213 variants in 110 genes with 78 novel variants. WES and single gene testing identified a causal variant in 65.5% and 34.5% cases, respectively. The total diagnostic rate of WES was 60.7%. Lysosomal disorders (27.3%; GM2-gangliosidosis-9.8%, MLD-6.1%, KD-4.5%), amino and organic acid disorders (17.15%; Canavan disease-4.5%, L-2-HGA-3.6%), mitochondrial leukodystrophies (12.6%), ion and water homeostasis disorders (7.3%; MLC-4.5%), peroxisomal disorders (6.5%; X-ALD-3.6%), and myelin protein disorders (3.6%; PMLD-3.6%) were the most commonly diagnosed disorders. Thirty-seven percent of cases had a pathogenic variant in nine genes (ARSA, HEXA, ASPA, MLC1, GALC, GJC2, ABCD1, L2HGDH, GCDH). This study highlights the most common types as well as the genetic heterogeneity of LDs in Iranian children.

Epidemiological, Clinical, and Laboratory Characteristics of Acute Disseminated Encephalomyelitis in Children: A Retrospective Study.

OBJECTIVES: We aimed to study the precipitating factors, demographic data, clinical and radiological manifestations, electroencephalography and laboratory findings, as well as association with infections, immunization and incidence of relapse of acute disseminated encephalomyelitis (ADEM) in children admitted to Mofid Children Hospital, Tehran, Iran from Mar 2013 to Mar 2016. MATERIALS & METHODS: A 3-yr retrospective review of 29 children with definite final diagnosis of ADEM in Mofid Hospital in Tehran, Iran was performed. The diagnosis was based on specified criteria, including a presumed acute demyelinating process with no history of unexplained neurological symptoms and at least one demyelinating lesion shown on magnetic resonance imaging without evidence of previous destructive white matter lesions. RESULTS: Overall, 29 children diagnosed as ADEM were studied in terms of demographic characteristics, clinical manifestations and laboratory findings in two groups according to their recurrence. The mean age of the patients with recurrence was less than those without it were. It was more common in females but the difference was not statistically meaningful. There was no relationship between the season of the first episode of the disease and the recurrence incidence. Moreover, the relationship between viral infections and recurrence was statistically non-meaningful. No relationship between the recurrence of ADEM and clinical manifestations, radiological and laboratory findings was found. CONCLUSION: The reason for high rate of recurrence in our patients may be related to the younger age of children in our study.