title: Overlap phenotype between CMT1A and hereditary neuropathy with liability to pressure palsies caused by the novel small in-frame deletion c.407_418del12 in PMP22 gene.
abstract: We report monozygotic twins, who presented with a clinical picture of Charcot-Marie-Tooth disease type 1 (CMT1) with bilateral foot drop, pes cavus, thoracic kyphosis, and scoliosis. Hereditary neuropathy with liability to pressure palsies (HNPP) showed up in one of them. Neurography showed demyelinating neuropathy, typical for CMT1, and transient conduction block in the ulnar nerve correlating with clinical ulnar palsy due to minor mechanical stress in only one of them. Genetic analysis revealed novel small de novo deletion c.407_418del12 in the PMP22 gene. Our patient shows the rarely reported combination of CMT1A and HNPP, caused by an in-frame deletion in the PMP22 gene. HNPP is in the majority of cases correlated with heterozygous deletion of the whole PMP22 gene or other mutations leading to functional haploinsufficiency. The cases give further evidence that pathogenesis of HNPP is not completely understood and can obviously result from existence of a defective protein, too. The intrafamiliar phenotypic variability, even in monozygotic twins, confirms the well-known fact that factors apart from genetics contribute to the clinical course.
authors.affiliation: Dr. v. Hauner Children Hospital, Ludwig-Maximilian University of Munich, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Vill
authors.affiliation: Genetikum Center for Human Genetics, Neu-Ulm, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Kuhn
authors.affiliation: Genetikum Center for Human Genetics, Neu-Ulm, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Gläser
authors.affiliation: Dr. v. Hauner Children Hospital, Ludwig-Maximilian University of Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Müller-Felber
mesh_terms: D001176:Arthrogryposis / Q000150:complications* / Q000235:genetics*; D002607:Charcot-Marie-Tooth Disease / Q000150:complications* / Q000235:genetics*; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D015417:Hereditary Sensory and Motor Neuropathy / Q000150:complications* / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D009185:Myelin Proteins / Q000235:genetics*; D009431:Neural Conduction / Q000235:genetics; D010375:Pedigree; D010641:Phenotype
chemical_list: D009185:Myelin Proteins; C073687:PMP22 protein, human