Subcortical Cysts Research Articles

Molecular Genetic Studies in Indian Patients With Megalencephalic Leukoencephalopathy

Mutations in the MLC1 gene cause megalencephalic leukoencephalopathy with subcortical cysts. We sought to identify mutations in the MLC1 gene, to evaluate the genotype-phenotype correlation, and to develop a strategy for diagnosing Indian patients with megalencephalic leukoencephalopathy. Forty patients were enrolled. We developed a rapid restriction fragment length polymorphism method to screen a common mutation, c.135_136insC. Rare and novel mutations were screened by conformation-sensitive gel electrophoresis, followed by sequencing. Three previously reported and two novel mutations were identified in 37 patients. The presence of the c.135_136insC mutation in 29 patients of the Agarwal community suggests a founder effect. The mutation c.959C>A was evident in four patients, and appears to be the second commonest mutation. Genotype could not predict phenotype. We recommend screening for the commonest mutation (c.135_136insC), followed by the next commonest mutation (c.959C>A), and then other rare mutations, using conformation-sensitive gel electrophoresis analysis or direct sequencing.

4PS3.1 Mutant GlialCAM causes Megalencephalic Leukoencephalopathy with Subcortical Cysts (MLC), benign familial macrocephaly, and macrocephaly with mental retardation with or without autism

4PS3.1 Mutant GlialCAM causes Megalencephalic Leukoencephalopathy with Subcortical Cysts (MLC), benign familial macrocephaly, and macrocephaly with mental retardation with or without autism

Infant subcortical cystic leucomalacia: A distinct pathological entity resulting from impaired fluid handling

Background In the first months of life the subcortical white matter appears prone to fluid accumulation and cystic change. This condition has generally been considered to be due to hypoxic-ischaemic injury (HII) and is grouped with other forms of white matter disease including periventricular leucomalacia (PVL). Aims Our aim was to describe the sequential tissue changes in the formation of subcortical cystic leucomalacia in the infant brain and to delineate this from other forms of white matter disease in order to better understand its pathogenesis and aetiology. Study design Standard samples of the frontal lobe, including subcortical white matter, were stained to demonstrate the cellular processes responsible for subcortical cyst formation in infants who had died from global hypoxic-ischaemic injury (HII) and brain swelling. Cases were of infants who had survived for known periods after collapse in order to determine the time course of the pathological changes. Subjects 20 infants under 5 months of age with global HII and no other primary brain pathology, and who had survived for between 2 h and 13 days after collapse. Outcome measures The description of the sequential changes leading to subcortical cyst formation in infants after severe global HII. Results With increasing time of survival after global HII the subcortical white matter became more oedematous. Subcortical cysts were seen after one day but were most common in infants surviving more than 5 days. Cysts were not associated with cellular responses and seemed to be the result of fluid accumulation. The pathology was quite distinct from PVL which is due to tissue necrosis. Conclusions Subcortical leucomalacia results from fluid accumulation and not necrosis. Predisposition to fluid accumulation may be age-related and due to impairment of fluid handling pathways which remain immature in this age group. Potential mechanisms are discussed.

Knockdown of MLC1 in primary astrocytes causes cell vacuolation: A MLC disease cell model

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare type of leukodystrophy, in the majority of cases caused by mutations in the MLC1 gene. MRI from MLC patients shows diffuse cerebral white matter signal abnormality and swelling, with evidence of increased water content. Histopathology in a MLC patient shows vacuolation of myelin, which causes the cerebral white matter swelling. MLC1 protein is expressed in astrocytic processes that are part of blood- and cerebrospinal fluid-brain barriers. We aimed to create an astrocyte cell model of MLC disease. The characterization of rat astrocyte cultures revealed MLC1 localization in cell–cell contacts, which contains other proteins described typically in tight and adherent junctions. MLC1 localization in these contacts was demonstrated to depend on the actin cytoskeleton; it was not altered when disrupting the microtubule or the GFAP networks. In human tissues, MLC1 and the protein Zonula Occludens 1 (ZO-1), which is linked to the actin cytoskeleton, co-localized by EM immunostaining and were specifically co-immunoprecipitated. To create an MLC cell model, knockdown of MLC1 in primary astrocytes was performed. Reduction of MLC1 expression resulted in the appearance of intracellular vacuoles. This vacuolation was reversed by the co-expression of human MLC1. Re-examination of a human brain biopsy from an MLC patient revealed that vacuoles were also consistently present in astrocytic processes. Thus, vacuolation of astrocytes is also a hallmark of MLC disease.

Mutant GlialCAM Causes Megalencephalic Leukoencephalopathy with Subcortical Cysts, Benign Familial Macrocephaly, and Macrocephaly with Retardation and Autism

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a leukodystrophy characterized by early-onset macrocephaly and delayed-onset neurological deterioration. Recessive MLC1 mutations are observed in 75% of patients with MLC. Genetic-linkage studies failed to identify another gene. We recently showed that some patients without MLC1 mutations display the classical phenotype; others improve or become normal but retain macrocephaly. To find another MLC-related gene, we used quantitative proteomic analysis of affinity-purified MLC1 as an alternative approach and found that GlialCAM, an IgG-like cell adhesion molecule that is also called HepaCAM and is encoded by HEPACAM, is a direct MLC1-binding partner. Analysis of 40 MLC patients without MLC1 mutations revealed multiple different HEPACAM mutations. Ten patients with the classical, deteriorating phenotype had two mutations, and 18 patients with the improving phenotype had one mutation. Most parents with a single mutation had macrocephaly, indicating dominant inheritance. In some families with dominant HEPACAM mutations, the clinical picture and magnetic resonance imaging normalized, indicating that HEPACAM mutations can cause benign familial macrocephaly. In other families with dominant HEPACAM mutations, patients had macrocephaly and mental retardation with or without autism. Further experiments demonstrated that GlialCAM and MLC1 both localize in axons and colocalize in junctions between astrocytes. GlialCAM is additionally located in myelin. Mutant GlialCAM disrupts the localization of MLC1-GlialCAM complexes in astrocytic junctions in a manner reflecting the mode of inheritance. In conclusion, GlialCAM is required for proper localization of MLC1. HEPACAM is the second gene found to be mutated in MLC. Dominant HEPACAM mutations can cause either macrocephaly and mental retardation with or without autism or benign familial macrocephaly.

A Commentary on Identification of novel MLC1 mutations in Chinese patients with megalencephalic leukoencephalopathy with subcortical cysts (MLC)

A Commentary on Identification of novel MLC1 mutations in Chinese patients with megalencephalic leukoencephalopathy with subcortical cysts (MLC)

Megalencephalic leukoencephalopathy with subcortical cysts: A report of four cases

Megalencephalic leukoencephalopathy with subcortical cysts is an inherited autosomal recessive disorder with characteristic MRI features and a variable but mild clinical course. Frontal and temporal subcortical cysts are the diagnostic hallmark. It usually presents with pyramidal and cerebellar signs. Megalencephaly is usually detected early. Seizures may be present but are usually easily controlled. It has been reported commonly from a certain ethnicity of northern Indian origin, but its presence is global. We encountered four patients and describe the clinical and radiological features of these patients. Seizures though reported to be uncommon were seen in all our patients. Neuropsychiatric features have not been described as presentation so far but one of our patients had moderately severe depression. All the patients were diagnosed by MRI features and they responded well to symptomatic treatment.

Identification of novel MLC1 mutations in Chinese patients with megalencephalic leukoencephalopathy with subcortical cysts (MLC)

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal, recessively inherited disease caused by mutations in the MLC1 gene. Most of the previously published studies have been carried out in ethnic populations other than the Chinese. In this study, the analysis of clinical features and MLC1 mutation screening were performed in 13 Chinese patients for the first time. A total of 10 MLC1 mutations were identified in these patients, including five novel missense mutations (c.65G>A, p.R22Q; c.95C>T, p.A32V; c.218G>A, p.G73E; c.823G>A, p.A275T; c.832T>C, p.Y278H), one novel splicing mutation (c.772-1G>C in IVS9-1), one novel small deletion (c.907_930del, p.V303_L310del), one known nonsense mutation (c.593delCTCA, p.Y198X) and two known missense mutations (c.206C>T, p.S69L; c.353C>T, p.T118M). Mutation c.772-1G>C in IVS9-1, accounting for 27.3% (3/11) of the total number of genetically confirmed patients found in this study, is thus a putative hot-spot mutation in the present study group. The existence of a unique MLC1 mutation spectrum in Chinese MLC patients was shown. A systemic study to assess the mutation spectra in different populations should be undertaken.

Novel mutations of the MLC1 gene in Turkish patients

Megalencephalic Leukoencephalopathy with Subcortical Cysts (MLC) is a rare autosomal recessive disease presenting with increased head circumference at birth or in early infancy. MLC1 (MIM 605908) mutations are responsible for this disorder. In this study, we sequenced the entire coding region of the MLC1 gene in 13 patients and detected five novel nucleotide variations in six of them. Two of the novel variations created a missense amino acid change and the other three were located in the introns and were putative splice mutations. One novel missense variation was observed in two unrelated patients from the central Black Sea region, and the data suggested a founder haplotype for this novel variation. Similarly, three unrelated patients with the previously reported p.Thr118Arg mutation shared a common haplotype. These data suggest an Anatolian origin for these two mutations. As in the previous reports, it is not possible to correlate the clinical phenotype of the patients with the mutation spectra.

Peculiar neuroimaging and electrophysiological findings in a patient with biotinidase deficiency

We report a patient with biotinidase deficiency with peculiar findings on her MRI brain. Subcortical cysts combined with Dandy Walker cyst on the brain MRI have never been reported. There are many documented case reports of biotinidase deficiency and several of them have included findings on neuroimaging. Subcortical cysts have been documented in one patient with biotinidase deficiency previously and on autopsy in one other patient. Video EEG on the same patient showed evidence of symptomatic generalized epilepsy.

96 The Leukoencephalopathies of Childhood: Findings From a National Prospective Study

Background and aims: To report the distribution of leukoencephalopathies in children identified by this prospective population-based study. Methods: 2802 children with suspected progressive intellectual and neurological deterioration (PIND) were notified via the British Paediatric Surveillance Unit (BPSU) between 1997 and 2009. An expert group reviewed clinical data and confirmed diagnoses where possible. An independent expert reviewed the available scans of children with unclassified leukoencephalopathies. Results: 1132 of the PIND children had an underlying diagnosis and of these 295 had one of the leukoencephalopathies. The distribution of diagnosed leukoencephalopathies was as follows: metachromatic leukodystrophy 62, X-linked adrenoleukodystrophy 60, Krabbe disease 39, Canavan disease 16, Alexander disease 13, leukoencephalopathy with vanishing white matter 12, Aicardi-Goutieres syndrome 12, Pelizaeus-Merzbacher disease 11, megalencephalic leukoencephalopathy with subcortical cysts 8, multiple sulphatase deficiency 6, multiple sclerosis 3, peroxisomal bifunctional D-protein deficiency 2, peroxisomal biogenesis defect 1. There were 50 children in the unclassified leukoencephalopathy group. In 32 the scans were reviewed and 19 were placed in a hypomyelination sub-group, the other 13 remaining in the unclassified leukoencephalopathy group with the 18 whose scans could not be reviewed. Conclusions: Leukoencephalopathies comprised 26% of PIND children with a known diagnosis. This population based study gives the relative frequency of the different leukoencephalopathies, providing an aid to diagnosis in children with abnormal white matter on brain imaging. After rigorous investigation 16% (50/295) remained in an unclassified group, but this situation is evolving.

The β1 subunit of the Na,K-ATPase pump interacts with megalencephalic leucoencephalopathy with subcortical cysts protein 1 (MLC1) in brain astrocytes: new insights into MLC pathogenesis

Megalencephalic leucoencephalopathy with subcortical cysts (MLC) is a rare congenital leucodystrophy caused by mutations in MLC1, a membrane protein of unknown function. MLC1 expression in astrocyte end-feet contacting blood vessels and meninges, along with brain swelling, fluid cysts and myelin vacuolation observed in MLC patients, suggests a possible role for MLC1 in the regulation of fluid and ion homeostasis and cellular volume changes. To identify MLC1 direct interactors and dissect the molecular pathways in which MLC1 is involved, we used NH2-MLC1 domain as a bait to screen a human brain library in a yeast two-hybrid assay. We identified the β1 subunit of the Na,K-ATPase pump as one of the interacting clones and confirmed it by pull-downs, co-fractionation assays and immunofluorescence stainings in human and rat astrocytes in vitro and in brain tissue. By performing ouabain-affinity chromatography on astrocyte and brain extracts, we isolated MLC1 and the whole Na,K-ATPase enzyme in a multiprotein complex that included Kir4.1, syntrophin and dystrobrevin. Because Na,K-ATPase is involved in intracellular osmotic control and volume regulation, we investigated the effect of hypo-osmotic stress on MLC1/Na,K-ATPase relationship in astrocytes. We found that hypo-osmotic conditions increased MLC1 membrane expression and favoured MLC1/Na,K-ATPase-β1 association. Moreover, hypo-osmosis induced astrocyte swelling and the reversible formation of endosome-derived vacuoles, where the two proteins co-localized. These data suggest that through its interaction with Na,K-ATPase, MLC1 is involved in the control of intracellular osmotic conditions and volume regulation in astrocytes, opening new perspectives for understanding the pathological mechanisms of MLC disease.

Leukoencephalopathy with Anterior Temporal Cysts Due to Congenital CMV Infection Diagnosed Retrospectively

Leukoencephalopathy with subcortical cysts has been described in a variety of conditions. However, few reports have highlighted congenital CMV as a cause of this imaging finding. We report a 1-year-old girl with developmental delay and sensorineural hearing loss whose MRI brain showed abnormal white matter and temporal cysts. Congenital CMV infection was diagnosed retrospectively by examination of dried blood spot from the newborn screening card.

Megalencephalic leukoencephalopathy with cysts without MLC1 defect

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is an autosomal recessive disease characterized by early infantile macrocephaly and delayed motor and cognitive deterioration. Magnetic resonance imaging (MRI) shows diffusely abnormal and swollen cerebral white matter and subcortical cysts. On follow-up, atrophy ensues. Approximately 80% of MLC patients have mutations in MLC1. We report 16 MLC patients without MLC1 mutations. Eight retained the classical clinical and MRI phenotype. The other 8 showed major MRI improvement. They lacked motor decline. Five had normal intelligence; 3 displayed cognitive deficiency. In conclusion, 2 phenotypes can be distinguished among the non-MLC1 mutated MLC patients: a classical and a benign phenotype.

Analysis of CLCN2 as Candidate Gene for Megalencephalic Leukoencephalopathy with Subcortical Cysts

Mutations in the gene MLC1 are found in approximately 80% of the patients with the inherited childhood white matter disorder megalencephalic leukoencephalopathy with subcortical cysts (MLC). Genetic linkage studies have not led to the identification of another disease gene. We questioned whether mutations in CLCN2, coding for the chloride channel protein 2 (ClC-2), are involved in MLC. Mice lacking this protein develop white matter abnormalities, which are characterized by vacuole formation in the myelin sheaths, strikingly similar to the intramyelinic vacuoles in MLC. Sequence analysis of CLCN2 at genomic DNA and cDNA levels in 18 MLC patients without MLC1 mutations revealed some nucleotide changes, but they were predicted to be nonpathogenic. Further, in electrophysiological experiments, one of the observed amino acid changes was shown to have no effect on the ClC-2-mediated currents. In conclusion, we found no evidence suggesting that the CLCN2 gene is involved in MLC.

Maladies démyélinisantes d’origine génétique

Diagnosis of leukodystrophiesin adults is difficult. Diagnosis requires a collaborative approach including clinical,neuroradiological, biochemical, and genetic analyses. Less than thirty percent ofadult-onset leukodystrophies have a precise diagnosis. Improved neuroradiological knowledgeis making it possible to determine MRI (magnetic resonance imaging) phenotypes that point towards specific causes and specific diagnoses. The cavitary leukodystrophies includechildhood ataxia with central nervous system hypomyelination/vanishing white matter(CACH/VWM) syndromeand megalencephalic leukoencephalopathy with subcortical cysts (MLC). Damage tothe posterior spinal cord suggests leukoencephalopathy with damage to the brainstem and cord marrow and is accompanied by elevated lactate (LBSL).

Erosions Are the Most Relevant Magnetic Resonance Imaging Features in Quantification of Sacroiliac Joints in Ankylosing Spondylitis

To determine the most relevant radiological features in quantitative magnetic resonance imaging (MRI) of sacroiliac (SI) joints in patients with recent-onset ankylosing spondylitis (AS) versus patients with SI involvement due to other rheumatic diseases, or to degenerative SI pain. We retrospectively analyzed laboratory values, clinical data, and MRI of the SI joints of 179 patients admitted for evaluation of AS-suspicious SI pain. Standardized MRI sequences were performed at time of first presentation, then archived, and retrospectively quantitatively assessed using a modified SPARCC method for formal statistical comparisons. Of all patients, 27 (15%) were diagnosed with definite AS. The remainder had SI involvement in other rheumatic diseases, HLA-B27- spondyloarthropathy, or nonspecific degenerative changes. While joint space irregularities, bone marrow edema, subcortical cysts, and contrast medium enhancement were found in MRI of all patients, these features were inconsistent, and only erosions were statistically significantly (p < 0.02) in patients diagnosed with AS. Only in AS, the presence of erosions and the quantitative SPARCC erosion subscore correlated to a statistically significant degree (p < 0.02) with laboratory levels of inflammation. Erosions alone, not bone marrow edema or contrast medium enhancement, are the most disease-specific measurable imaging findings in SI MRI of patients with AS.

Pattern recognition on brain magnetic resonance imaging in alpha dystroglycanopathies

Alpha dystroglycanopathies are heterogeneous group of disorders both phenotypically and genetically. A subgroup of these patients has characteristic brain imaging findings. Four patients with typical imaging findings of alpha dystroglycanopathy are reported. Phenotypic features included: global developmental delay, contractures, hypotonia and oculomotor abnormalities in all. Other manifestations were consanguinity (3), seizures (3), macrocephaly (1), microcephaly (3), retinal changes (2) and hypogenitalism (2). Magnetic resonance imaging (MRI) of the brain revealed polymicrogyria, white matter changes, pontine hypoplasia, and subcortical cerebellar cysts in all the patients, ventriculomegaly, callosal abnormalities, and absent septum pellucidum in two and Dandy -Walker variant malformation in three. Magnetic resonace imaging of the first cousin of one the patient had the same characteristic imaging features. Brain imaging findings were almost identical despite heterogeneity in clinical presentation and histopathological features. Pattern recognition of MR imaging features may serve as a clue to the diagnosis of alpha dystroglycanopathy.

Megaloencephalic leukoencephalopathy with subcortical cyst formation (van der Knaap disease)

A child born at full term developed macrocephaly in infancy with regression of motor skills and cerebellar ataxia starting at age 3 that progressively worsened. Axial T2 weighted (T2-W) MRI (Fig. 1) shows diffuse white matter hyperintensity involving the subcortical fibers as well as sparing of the basal ganglia as thalami. Subcortical cyst formation is seen in the anterior temporal region on the sagittal T2-W image (Fig. 2, arrow). No contrast enhancement was noted. Megaloencephalic leukoencephalopathy (spongiform leukoencephalopathy or van der Knaap disease) is an autosomal-recessive, neurodegenerative disorder with macrocephaly in the first year of life but delayed onset

MLC1 trafficking and membrane expression in astrocytes: Role of caveolin-1 and phosphorylation

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare congenital leukodystrophy caused by mutations in the MLC1 gene that encodes a membrane protein of unknown function. In the brain MLC1 protein is mainly expressed in astrocyte end-feet, localizes in lipid rafts and associates with the dystrophin glycoprotein complex (DGC). Using pull-down and co-fractionation assays in cultured human and rat astrocytes, we show here that MLC1 intracellular domains pull-down the DGC proteins syntrophin, dystrobrevin, Kir4.1 and caveolin-1, the structural protein of caveolae, thereby supporting a role for DGC and caveolar structures in MLC1 function. By immunostaining and subcellular fractionation of cultured rat or human astrocytes treated with agents modulating caveolin-mediated trafficking, we demonstrate that MLC1 is also expressed in intracellular vesicles and endoplasmic reticulum and undergoes caveolae/raft-mediated endocytosis. Inhibition of endocytosis, cholesterol lowering and protein kinases A- and C-mediated MLC1 phosphorylation favour the expression of membrane-associated MLC1. Because pathological mutations prevent MLC1 membrane expression, the identification of substances regulating MLC1 intracellular trafficking is potentially relevant for the therapy of MLC.