title: Megalencephalic leukoencephalopathy with subcortical cysts type 1 (MLC1) due to a homozygous deep intronic splicing mutation (c.895-226T>G) abrogated in vitro using an antisense morpholino oligonucleotide.
abstract: Megalencephalic leukoencephalopathy with subcortical cysts is an autosomal recessive disease characterized by early onset macrocephaly; developmental delay; motor disability in the form of progressive spasticity and ataxia; seizures; cognitive decline; and characteristic magnetic resonance imaging findings. Mutations in two genes, MLC1 (22q13.33; 75 % of patients) or HEPACAM (11q24; 20 % of patients), are associated with the disease. We describe an adult MLC patient with moderate clinical symptoms. MLC1 cDNA analysis from lymphoblasts showed a strong transcript reduction and identified a 246-bp pseudoexon containing a premature stop codon between exons 10 and 11, due to a homozygous c.895-226 T>G deep-intronic mutation. This category of mutations is often overlooked, being outside of canonically sequenced genomic regions. The mutation c.895-226 T>G has a leaky effect on splicing leaving part of the full-length transcript. Its role on splicing was confirmed using a minigene assay and an antisense morpholinated oligonucleotide targeted to the aberrant splice site in vitro, which partially abrogated the mutation effect.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Torino, via Santena, 19-10126 Torino, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mancini
authors.forename: Giovanna
authors.initials: G
authors.lastname: Vaula
authors.forename: Laura
authors.initials: L
authors.lastname: Scalzitti
authors.forename: Simona
authors.initials: S
authors.lastname: Cavalieri
authors.forename: Enrico
authors.initials: E
authors.lastname: Bertini
authors.forename: Chiara
authors.initials: C
authors.lastname: Aiello
authors.forename: Cinzia
authors.initials: C
authors.lastname: Lucchini
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gatti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Brussino
authors.forename: Alfredo
authors.initials: A
authors.lastname: Brusco
mesh_terms: D001921:Brain / Q000473:pathology; D003560:Cysts / Q000175:diagnosis* / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons; D005192:Family Health; D005260:Female; D020279:Hereditary Central Nervous System Demyelinating Diseases / Q000175:diagnosis* / Q000235:genetics*; D006801:Humans; D007438:Introns; D008214:Lymphocytes / Q000166:cytology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics; D008875:Middle Aged; D008957:Models, Genetic; D009154:Mutation; D016376:Oligonucleotides, Antisense / Q000235:genetics*; D010375:Pedigree; D012326:RNA Splicing; D017422:Sequence Analysis, DNA
chemical_list: C425069:MLC1 protein, human; D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense