title: Familial periventricular nodular heterotopia, epilepsy and Melnick-Needles Syndrome caused by a single FLNA mutation with combined gain-of-function and loss-of-function effects.
abstract: BACKGROUND
  Loss-of-function mutations of the FLNA gene cause a neuronal migration disorder defined as X-linked periventricular nodular heterotopia (PNH); gain-of-function mutations are associated with a group of X-linked skeletal dysplasias designed as otopalatodigital (OPD) spectrum. We describe a family in which a woman and her three daughters exhibited a complex phenotype combining PNH, epilepsy and Melnick-Needles syndrome (MNS), a skeletal disorder assigned to the OPD spectrum. All four individuals harboured a novel non-conservative missense mutation in FLNA exon 3.
  
  
  METHODS
  In all affected family members, we performed mutation analysis of the FLNA gene, RT-PCR, ultradeep sequencing analysis in FLNA cDNAs and western blot in lymphocyte cells to further characterise the mutation. We also assessed the effects on RT-PCR products of treatment of patients' lymphocytes with cycloheximide, a nonsense mediated mRNA decay (NMD) inhibitor.
  
  
  RESULTS
  We identified a novel c.622G>C change in FLNA exon 3, leading to the substitution of a highly conserved aminoacid (p.Gly208Arg). Gel electrophoresis and ultradeep sequencing revealed the missense mutation as well as retention of intron 3. Cycloheximide treatment demonstrated that the aberrant mRNA transcript-retaining intron 3 is subjected to NMD. Western blot analysis confirmed reduced FLNA levels in lymphocyte cells.
  
  
  CONCLUSIONS
  The novel c.622G>C substitution leads to two aberrant FLNA transcripts, one of which carries the missense mutation, plus a longer transcript resulting from intron 3 retention. We propose that the exceptional co-occurrence of PNH and MNS, two otherwise mutually exclusive allelic phenotypes, is the consequence of a single mutational event resulting in co-occurring gain-of-function and loss-of-function effects.
authors.affiliation: Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital-University of Florence, Florence, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Parrini
authors.affiliation: Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital-University of Florence, Florence, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Mei
authors.affiliation: Medical Genetic Unit, AORN Cardarelli, Naples, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Pisanti
authors.affiliation: Molecular and Cell Biology Laboratory, Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital, Florence, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Catarzi
authors.affiliation: Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital-University of Florence, Florence, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pucatti
authors.affiliation: Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital-University of Florence, Florence, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Bianchini
authors.affiliation: Quantitative and Functional Neuroradiology Research Program, Meyer Children Hospital and Careggi General Hospital, Florence, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
authors.affiliation: Unit of Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Research Hospital, Rome, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Bertini
authors.affiliation: Molecular and Cell Biology Laboratory, Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital, Florence, Italy Department of Neurosciences, Psychology, Pharmacology and Child Health, University of Florence, Florence, Italy.
authors.forename: Amelia
authors.initials: A
authors.lastname: Morrone
authors.affiliation: Medical Genetic Unit, AORN Cardarelli, Naples, Italy.
authors.forename: Maria Luigia
authors.initials: ML
authors.lastname: Cavaliere
authors.affiliation: Pediatric Neurology and Neurogenetics Unit and Laboratories, Neuroscience Department, A. Meyer Children's Hospital-University of Florence, Florence, Italy.
authors.forename: Renzo
authors.initials: R
authors.lastname: Guerrini
mesh_terms: D001483:Base Sequence; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D001921:Brain / Q000473:pathology; D019295:Computational Biology; D004252:DNA Mutational Analysis; D004827:Epilepsy / Q000235:genetics*; D005091:Exons; D005260:Female; D064448:Filamins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D050172:Genes, X-Linked; D056726:Genetic Association Studies; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008969:Molecular Sequence Data; D009154:Mutation; D020125:Mutation, Missense; D059365:Nonsense Mediated mRNA Decay; D010009:Osteochondrodysplasias / Q000175:diagnosis / Q000235:genetics*; D010375:Pedigree; D054091:Periventricular Nodular Heterotopia / Q000175:diagnosis / Q000235:genetics*; D012326:RNA Splicing; D011859:Radiography; D016415:Sequence Alignment; D013577:Syndrome; D049951:X Chromosome Inactivation
chemical_list: C578663:FLNA protein, human; D064448:Filamins
keywords: FLNA; Melnick-Needles syndrome; Periventricular nodular heterotopia; epilepsy; mutation