title: Clinical, neuroimaging, and genetic characteristics of megalencephalic leukoencephalopathy with subcortical cysts in Egyptian patients.
abstract: BACKGROUND
  Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare and genetically heterogeneous cerebral white matter disease. Clinically, it is characterized by macrocephaly, developmental delay, and seizures. We explore the clinical spectrum, neuroimaging characteristics, and gene involvement in the first patients with megalencephalic leukoencephalopathy with subcortical cysts described from Egypt.
  
  
  METHODS
  Six patients were enrolled from three unrelated families. Patient inclusion criteria were macrocephaly, developmental delay, normal urinary organic acids, and brain imaging of diffuse cerebral white matter involvement. Direct sequencing of the MLC1 gene in patients' families and GliaCAM in one questionable case was performed using BigDye Terminator cycle sequencing.
  
  
  RESULTS
  Clinical heterogeneity, both intra- and interfamilial, was clearly evident. Developmental delays ranged from globally severe or moderate to mild delay in achieving walking or speech. Head circumference above the ninety-seventh percentile was a constant feature. Neuroimaging featured variability in white matter involvement and subcortical cysts. However, findings of posterior fossa changes and brain stem atrophy were frequently (66.6%) identified in these Egyptian patients. Discrepancy between severe brain involvement and normal mental functions was evident, particularly in patients from the third family. MLC1 mutations were confirmed in all patients. Deletion/insertion mutation in exon 11 (c.908-918delinsGCA, p.Val303 Gly fsX96) was recurrent in two families, whereas a missense mutation in exon 10 (c.880 C > T, p.Pro294Ser) was identified in the third family.
  
  
  CONCLUSIONS
  This report extends our knowledge of the clinical and neuroimaging features of megalencephalic leukoencephalopathy with subcortical cysts. It confirms the apparent lack of selective disadvantage of MLC1 mutations on gamete conception and transmission as supported by the presence of multiple affected siblings in Egyptian families.
authors: Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt.
authors: Iman G
authors: IG
authors: Mahmoud
authors: Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt.
authors: Marwa
authors: M
authors: Mahmoud
authors: Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt.
authors: Miral
authors: M
authors: Refaat
authors: Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt.
authors: Marian
authors: M
authors: Girgis
authors: Department of Pediatrics, 6(th) October University, Cairo, Egypt.
authors: Nevin
authors: N
authors: Waked
authors: Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt.
authors: Ameera
authors: A
authors: El Badawy
authors: Neurology and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt.
authors: Laila
authors: L
authors: Selim
authors: Genetics and Neurometabolic Departments, Cairo University Children Hospital, Cairo, Egypt.
authors: Sawsan
authors: S
authors: Hassan
authors: Stem Cell Research Laboratory, Centre for Advanced Sciences-National Research Centre, Cairo, Egypt; Neurogenetics Laboratory, Weill Cornell Medical College in Qatar, Doha, Qatar; Department of Neurology, Weill Cornell Medical College, New York, New York. Electronic address: aka2005@qatar-med.cornell.edu.
authors: Alice K
authors: AK
authors: Abdel Aleem
mesh_terms: D000293:Adolescent; D000595:Amino Acid Sequence; D001921:Brain / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003560:Cysts / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D002658:Developmental Disabilities / Q000209:etiology; D004534:Egypt; D005190:Family; D006257:Head / Q000473:pathology; D020279:Hereditary Central Nervous System Demyelinating Diseases / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D020125:Mutation, Missense; D009929:Organ Size; D017384:Sequence Deletion
chemical_list: C425069:MLC1 protein, human; D008565:Membrane Proteins
keywords: GliaCAM gene; MLC1 gene; Van der Knaap disease; developmental delay; macrocephaly; megalencephalic leukodystrophy; subcortical cysts