Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0007758 (cerebellar ataxia)
 3,609 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a progressive inherited neurological disorder characterized by macrocephaly, deterioration in motor functions and cerebellar ataxia. In Israel the disease is found in an increased frequency among Libyan Jews. The disease is caused by mutations in the MLC1 gene, which encodes a putative CNS membrane transporter. We describe three novel mutations (p.G59E, p.P92S, and 134_136insC) in seven MLC families. One of these mutations, p.G59E, was found in the vast majority of MLC patients in Israel. Screening of 200 normal Libyan Jewish individuals for the p.G59E mutation, revealed a carrier rate of 1/40 compared with an expected carrier rate of 1/81. Several explanations could account for this difference the most likely one is an admixture of the Libyan Jewish population.
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PMID:Megalencephalic leukoencephalopathy with subcortical cysts; a founder effect in Israeli patients and a higher than expected carrier rate among Libyan Jews. 1218 96

Megalencephalic leucoencephalopathy with subcortical cysts is a genetic brain disorder with onset in early childhood. Affected infants develop macrocephaly within the first year of life, after several years followed by slowly progressive, incapacitating cerebellar ataxia and spasticity. From early on, magnetic resonance imaging shows diffuse signal abnormality and swelling of the cerebral white matter, with evidence of highly increased white matter water content. In most patients, the disease is caused by mutations in the gene MLC1, which encodes a plasma membrane protein almost exclusively expressed in brain and at lower levels in leucocytes. Within the brain, MLC1 is mainly located in astrocyte-astrocyte junctions adjacent to the blood-brain and cereborspinal fluid-brain barriers. Thus far, the function of MLC1 has remained unknown. We tested the hypothesis that MLC1 mutations cause a defect in ion currents involved in water and ion homeostasis, resulting in cerebral white matter oedema. Using whole-cell patch clamp studies we demonstrated an association between MLC1 expression and anion channel activity in different cell types, most importantly astrocytes. The currents were absent in chloride-free medium and in cells with disease-causing MLC1 mutations. MLC1-dependent currents were greatly enhanced by hypotonic pretreatment causing cell swelling, while ion channel blockers, including Tamoxifen, abolished the currents. Down regulation of endogenous MLC1 expression in astrocytes by small interfering RNA greatly reduced the activity of this channel, which was rescued by overexpression of normal MLC1. The current-voltage relationship and the pharmacological profiles of the currents indicated that the channel activated by MLC1 expression is a volume-regulated anion channel. Such channels are involved in regulatory volume decrease. We showed that regulatory volume decrease was hampered in lymphoblasts from patients with megalencephalic leucoencephalopathy. A similar trend was observed in astrocytes with decreased MLC1 expression; this effect was rescued by overexpression of normal MLC1. In the present study, we show that absence or mutations of the MLC1 protein negatively impact both volume-regulated anion channel activity and regulatory volume decrease, indicating that megalencephalic leucoencephalopathy is caused by a disturbance of cell volume regulation mediated by chloride transport.
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PMID:Megalencephalic leucoencephalopathy with cysts: defect in chloride currents and cell volume regulation. 2200 81

Megalencephalic leukoencephalopathy (MLC) with subcortical cysts, also known as Van der Knaap disease (MIM #604004) is an autosomal recessive neurological disorder characterized by early onset macrocephaly, epilepsy, neurological deterioration with cerebellar ataxia and spasticity. An 8-month-old boy was admitted to our pediatric neurology clinic with macrocephaly. His brain magnetic resonance imaging (MRI) revealed bilateral, diffuse, symmetric structural white matter abnormalities, relatively sparing the cerebellum and bilateral subcortical temporal cysts. The diagnosis of Van der Knaap disease was suspected based on the clinical features and imaging findings and the genetic analysis revealed a novel homozygous c.768+2T>C mutation of the MLC1 gene. For determination of the novel splice-site mutation's effect, cDNA amplification was performed. cDNA analysis showed that the splice-site c.768+2T>C mutation gave rise to exon 9 skipping.
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PMID:A Novel Splice-site Mutation on the MLC1 Gene Leading to Exon 9 Skipping and Megalencephalic Leukoencephalopathy with Subcortical Cysts in a Turkish Patient. 3194 23