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Magri F, Colombo I, Del Bo R, Previtali S, Brusa R, Ciscato P, Scarlato M, Ronchi D, D'Angelo MG, Corti S, Moggio M, Bresolin N, Comi GP. ISPD mutations account for a small proportion of Italian Limb Girdle Muscular Dystrophy cases. BMC Neurol 2015; 15:172. [PMID: 26404900 PMCID: PMC4582941 DOI: 10.1186/s12883-015-0428-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 09/14/2015] [Indexed: 12/16/2022] Open
Abstract
Background Limb Girdle Muscular Dystrophy (LGMD), caused by defective α-dystroglycan (α-DG) glycosylation, was recently associated with mutations in Isoprenoid synthase domain-containing (ISPD) and GDP-mannose pyrophosphorylase B (GMPPB) genes. The frequency of ISPD and GMPPB gene mutations in the LGMD population is unknown. Methods We investigated the contributions of ISPD and GMPPB genes in a cohort of 174 Italian patients with LGMD, including 140 independent probands. Forty-one patients (39 probands) from this cohort had not been genetically diagnosed. The contributions of ISPD and GMPPB were estimated by sequential α-DG immunohistochemistry (IHC) and mutation screening in patients with documented α-DG defect, or by direct DNA sequencing of both genes when muscle tissue was unavailable. Results We performed α-DG IHC in 27/39 undiagnosed probands: 24 subjects had normal α-DG expression, two had a partial deficiency, and one exhibited a complete absence of signal. Direct sequencing of ISPD and GMPPB revealed two heterozygous ISPD mutations in the individual who lacked α-DG IHC signal: c.836-5 T > G (which led to the deletion of exon 6 and the production of an out-of-frame transcript) and c.676 T > C (p.Tyr226His). This patient presented with sural hypertrophy and tip-toed walking at 5 years, developed moderate proximal weakness, and was fully ambulant at 42 years. The remaining 12/39 probands did not exhibit pathogenic sequence variation in either gene. Conclusion ISPD mutations are a rare cause of LGMD in the Italian population, accounting for less than 1 % of the entire cohort studied (FKRP mutations represent 10 %), while GMPPB mutations are notably absent in this patient sample. These data suggest that the genetic heterogeneity of LGMD with and without α-DG defects is greater than previously realized. Electronic supplementary material The online version of this article (doi:10.1186/s12883-015-0428-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francesca Magri
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | - Irene Colombo
- Neuromuscular and Rare Disease Unit, Department of Neuroscience, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, via F. Sforza 35, 20132, Milan, Italy.
| | - Roberto Del Bo
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | - Stefano Previtali
- Inspe, Division of Neuroscience, San Raffaele, Via Olgettina 60, Milan, Italy.
| | - Roberta Brusa
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | - Patrizia Ciscato
- Neuromuscular and Rare Disease Unit, Department of Neuroscience, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, via F. Sforza 35, 20132, Milan, Italy.
| | - Marina Scarlato
- Inspe, Division of Neuroscience, San Raffaele, Via Olgettina 60, Milan, Italy.
| | - Dario Ronchi
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | | | - Stefania Corti
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | - Maurizio Moggio
- Neuromuscular and Rare Disease Unit, Department of Neuroscience, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, via F. Sforza 35, 20132, Milan, Italy.
| | - Nereo Bresolin
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
| | - Giacomo Pietro Comi
- Dino Ferrari Centre, Department of Neurological Sciences, University of Milan, I.R.C.C.S. Foundation Cà Granda, Ospedale Maggiore Policlinico, via F. Sforza 35, 20122, Milan, Italy.
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