Molecular Genetic Analysis of the PLP1 Gene in 38 Families with PLP1-related disorders: Identification and Functional Characterization of 11 Novel PLP1 Mutations

Serena Grossi, Stefano Regis, Roberta Biancheri, Matthew Mort, Susanna Lualdi, Enrico Bertini, Graziella Uziel, Odile Boespflug-Tanguy, Alessandro Simonati, Fabio Corsolini, Ercan Demir, Valentina Marchiani, Antonio Percesepe, Franco Stanzial, Andrea Rossi, Catherine Vaurs-Barrière, David N. Cooper, Mirella Filocamo

Research output: Contribution to journalArticle

Abstract

Background: The breadth of the clinical spectrum underlying Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is due to the extensive allelic heterogeneity in the X-linked PLP1 gene encoding myelin proteolipid protein (PLP). PLP1 mutations range from gene duplications of variable size found in 60-70% of patients to intragenic lesions present in 15-20% of patients. Methods. Forty-eight male patients from 38 unrelated families with a PLP1-related disorder were studied. All DNA samples were screened for PLP1 gene duplications using real-time PCR. PLP1 gene sequencing analysis was performed on patients negative for the duplication. The mutational status of all 14 potential carrier mothers of the familial PLP1 gene mutation was determined as well as 15/24 potential carrier mothers of the PLP1 duplication. Results and Conclusions. PLP1 gene duplications were identified in 24 of the unrelated patients whereas a variety of intragenic PLP1 mutations were found in the remaining 14 patients. Of the 14 different intragenic lesions, 11 were novel; these included one nonsense and 7 missense mutations, a 657-bp deletion, a microdeletion and a microduplication. The functional significance of the novel PLP1 missense mutations, all occurring at evolutionarily conserved residues, was analysed by the MutPred tool whereas their potential effect on splicing was ascertained using the Skippy algorithm and a neural network. Although MutPred predicted that all 7 novel missense mutations would be likely to be deleterious, in silico analysis indicated that four of them (p.Leu146Val, p.Leu159Pro, p.Thr230Ile, p.Ala247Asp) might cause exon skipping by altering exonic splicing elements. These predictions were then investigated in vitro for both p.Leu146Val and p.Thr230Ile by means of RNA or minigene studies and were subsequently confirmed in the case of p.Leu146Val. Peripheral neuropathy was noted in four patients harbouring intragenic mutations that altered RNA processing, but was absent from all PLP1-duplication patients. Unprecedentedly, family studies revealed the de novo occurrence of the PLP1 duplication at a frequency of 20%.

Original languageEnglish
Article number40
JournalOrphanet Journal of Rare Diseases
Volume6
Issue number1
DOIs
Publication statusPublished - 2011

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Molecular Biology
Mutation
Genes
Gene Duplication
Missense Mutation
Pelizaeus-Merzbacher Disease
Myelin Proteolipid Protein
Hereditary Spastic Paraplegia
Mothers
RNA
X-Linked Genes
Peripheral Nervous System Diseases
Computer Simulation
Real-Time Polymerase Chain Reaction
Exons
DNA

ASJC Scopus subject areas

  • Medicine(all)
  • Genetics(clinical)
  • Pharmacology (medical)

Cite this

Molecular Genetic Analysis of the PLP1 Gene in 38 Families with PLP1-related disorders : Identification and Functional Characterization of 11 Novel PLP1 Mutations. / Grossi, Serena; Regis, Stefano; Biancheri, Roberta; Mort, Matthew; Lualdi, Susanna; Bertini, Enrico; Uziel, Graziella; Boespflug-Tanguy, Odile; Simonati, Alessandro; Corsolini, Fabio; Demir, Ercan; Marchiani, Valentina; Percesepe, Antonio; Stanzial, Franco; Rossi, Andrea; Vaurs-Barrière, Catherine; Cooper, David N.; Filocamo, Mirella.

In: Orphanet Journal of Rare Diseases, Vol. 6, No. 1, 40, 2011.

Research output: Contribution to journalArticle

Grossi, S, Regis, S, Biancheri, R, Mort, M, Lualdi, S, Bertini, E, Uziel, G, Boespflug-Tanguy, O, Simonati, A, Corsolini, F, Demir, E, Marchiani, V, Percesepe, A, Stanzial, F, Rossi, A, Vaurs-Barrière, C, Cooper, DN & Filocamo, M 2011, 'Molecular Genetic Analysis of the PLP1 Gene in 38 Families with PLP1-related disorders: Identification and Functional Characterization of 11 Novel PLP1 Mutations', Orphanet Journal of Rare Diseases, vol. 6, no. 1, 40. https://doi.org/10.1186/1750-1172-6-40
Grossi, Serena ; Regis, Stefano ; Biancheri, Roberta ; Mort, Matthew ; Lualdi, Susanna ; Bertini, Enrico ; Uziel, Graziella ; Boespflug-Tanguy, Odile ; Simonati, Alessandro ; Corsolini, Fabio ; Demir, Ercan ; Marchiani, Valentina ; Percesepe, Antonio ; Stanzial, Franco ; Rossi, Andrea ; Vaurs-Barrière, Catherine ; Cooper, David N. ; Filocamo, Mirella. / Molecular Genetic Analysis of the PLP1 Gene in 38 Families with PLP1-related disorders : Identification and Functional Characterization of 11 Novel PLP1 Mutations. In: Orphanet Journal of Rare Diseases. 2011 ; Vol. 6, No. 1.
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abstract = "Background: The breadth of the clinical spectrum underlying Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is due to the extensive allelic heterogeneity in the X-linked PLP1 gene encoding myelin proteolipid protein (PLP). PLP1 mutations range from gene duplications of variable size found in 60-70{\%} of patients to intragenic lesions present in 15-20{\%} of patients. Methods. Forty-eight male patients from 38 unrelated families with a PLP1-related disorder were studied. All DNA samples were screened for PLP1 gene duplications using real-time PCR. PLP1 gene sequencing analysis was performed on patients negative for the duplication. The mutational status of all 14 potential carrier mothers of the familial PLP1 gene mutation was determined as well as 15/24 potential carrier mothers of the PLP1 duplication. Results and Conclusions. PLP1 gene duplications were identified in 24 of the unrelated patients whereas a variety of intragenic PLP1 mutations were found in the remaining 14 patients. Of the 14 different intragenic lesions, 11 were novel; these included one nonsense and 7 missense mutations, a 657-bp deletion, a microdeletion and a microduplication. The functional significance of the novel PLP1 missense mutations, all occurring at evolutionarily conserved residues, was analysed by the MutPred tool whereas their potential effect on splicing was ascertained using the Skippy algorithm and a neural network. Although MutPred predicted that all 7 novel missense mutations would be likely to be deleterious, in silico analysis indicated that four of them (p.Leu146Val, p.Leu159Pro, p.Thr230Ile, p.Ala247Asp) might cause exon skipping by altering exonic splicing elements. These predictions were then investigated in vitro for both p.Leu146Val and p.Thr230Ile by means of RNA or minigene studies and were subsequently confirmed in the case of p.Leu146Val. Peripheral neuropathy was noted in four patients harbouring intragenic mutations that altered RNA processing, but was absent from all PLP1-duplication patients. Unprecedentedly, family studies revealed the de novo occurrence of the PLP1 duplication at a frequency of 20{\%}.",
author = "Serena Grossi and Stefano Regis and Roberta Biancheri and Matthew Mort and Susanna Lualdi and Enrico Bertini and Graziella Uziel and Odile Boespflug-Tanguy and Alessandro Simonati and Fabio Corsolini and Ercan Demir and Valentina Marchiani and Antonio Percesepe and Franco Stanzial and Andrea Rossi and Catherine Vaurs-Barri{\`e}re and Cooper, {David N.} and Mirella Filocamo",
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T1 - Molecular Genetic Analysis of the PLP1 Gene in 38 Families with PLP1-related disorders

T2 - Identification and Functional Characterization of 11 Novel PLP1 Mutations

AU - Grossi, Serena

AU - Regis, Stefano

AU - Biancheri, Roberta

AU - Mort, Matthew

AU - Lualdi, Susanna

AU - Bertini, Enrico

AU - Uziel, Graziella

AU - Boespflug-Tanguy, Odile

AU - Simonati, Alessandro

AU - Corsolini, Fabio

AU - Demir, Ercan

AU - Marchiani, Valentina

AU - Percesepe, Antonio

AU - Stanzial, Franco

AU - Rossi, Andrea

AU - Vaurs-Barrière, Catherine

AU - Cooper, David N.

AU - Filocamo, Mirella

PY - 2011

Y1 - 2011

N2 - Background: The breadth of the clinical spectrum underlying Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is due to the extensive allelic heterogeneity in the X-linked PLP1 gene encoding myelin proteolipid protein (PLP). PLP1 mutations range from gene duplications of variable size found in 60-70% of patients to intragenic lesions present in 15-20% of patients. Methods. Forty-eight male patients from 38 unrelated families with a PLP1-related disorder were studied. All DNA samples were screened for PLP1 gene duplications using real-time PCR. PLP1 gene sequencing analysis was performed on patients negative for the duplication. The mutational status of all 14 potential carrier mothers of the familial PLP1 gene mutation was determined as well as 15/24 potential carrier mothers of the PLP1 duplication. Results and Conclusions. PLP1 gene duplications were identified in 24 of the unrelated patients whereas a variety of intragenic PLP1 mutations were found in the remaining 14 patients. Of the 14 different intragenic lesions, 11 were novel; these included one nonsense and 7 missense mutations, a 657-bp deletion, a microdeletion and a microduplication. The functional significance of the novel PLP1 missense mutations, all occurring at evolutionarily conserved residues, was analysed by the MutPred tool whereas their potential effect on splicing was ascertained using the Skippy algorithm and a neural network. Although MutPred predicted that all 7 novel missense mutations would be likely to be deleterious, in silico analysis indicated that four of them (p.Leu146Val, p.Leu159Pro, p.Thr230Ile, p.Ala247Asp) might cause exon skipping by altering exonic splicing elements. These predictions were then investigated in vitro for both p.Leu146Val and p.Thr230Ile by means of RNA or minigene studies and were subsequently confirmed in the case of p.Leu146Val. Peripheral neuropathy was noted in four patients harbouring intragenic mutations that altered RNA processing, but was absent from all PLP1-duplication patients. Unprecedentedly, family studies revealed the de novo occurrence of the PLP1 duplication at a frequency of 20%.

AB - Background: The breadth of the clinical spectrum underlying Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is due to the extensive allelic heterogeneity in the X-linked PLP1 gene encoding myelin proteolipid protein (PLP). PLP1 mutations range from gene duplications of variable size found in 60-70% of patients to intragenic lesions present in 15-20% of patients. Methods. Forty-eight male patients from 38 unrelated families with a PLP1-related disorder were studied. All DNA samples were screened for PLP1 gene duplications using real-time PCR. PLP1 gene sequencing analysis was performed on patients negative for the duplication. The mutational status of all 14 potential carrier mothers of the familial PLP1 gene mutation was determined as well as 15/24 potential carrier mothers of the PLP1 duplication. Results and Conclusions. PLP1 gene duplications were identified in 24 of the unrelated patients whereas a variety of intragenic PLP1 mutations were found in the remaining 14 patients. Of the 14 different intragenic lesions, 11 were novel; these included one nonsense and 7 missense mutations, a 657-bp deletion, a microdeletion and a microduplication. The functional significance of the novel PLP1 missense mutations, all occurring at evolutionarily conserved residues, was analysed by the MutPred tool whereas their potential effect on splicing was ascertained using the Skippy algorithm and a neural network. Although MutPred predicted that all 7 novel missense mutations would be likely to be deleterious, in silico analysis indicated that four of them (p.Leu146Val, p.Leu159Pro, p.Thr230Ile, p.Ala247Asp) might cause exon skipping by altering exonic splicing elements. These predictions were then investigated in vitro for both p.Leu146Val and p.Thr230Ile by means of RNA or minigene studies and were subsequently confirmed in the case of p.Leu146Val. Peripheral neuropathy was noted in four patients harbouring intragenic mutations that altered RNA processing, but was absent from all PLP1-duplication patients. Unprecedentedly, family studies revealed the de novo occurrence of the PLP1 duplication at a frequency of 20%.

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