Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations

John A. McGrath, Gabrielle H.S. Ashton, Jemima E. Mellerio, Julio Cesar Salas-Alanis, Ole Swensson, James R. McMillan, Robin A.J. Eady

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

Non-sense mutations on both alleles of either the type VII collagen gene (COL7A1) or the genes encoding laminin 5 (LAMA3, LAMB3, or LAMC2) usually result in clinically severe forms of recessive dystrophic or junctional epidermolysis bullosa, respectively. In this study we assessed two unrelated families whose mutations in genomic DNA predicted severe recessive dystrophic epidermolysis bullosa or junctional epidermolysis bullosa phenotypes but in whom the manifestations were milder than expected. The recessive dystrophic epidermolysis bullosa patients had a homozygous single base-pair frameshift mutation in exon 19 of COL7A1 (2470insG). Clinically, there was generalized blistering but only mild scarring. Skin biopsy revealed positive type VII collagen immunoreactivity and recognizable anchoring fibrils. The junctional epidermolysis bullosa patients were compound heterozygotes for a frameshift/non-sense combination of mutations in exons 3 and 17 of LAMB3 (29insC/Q834X). These patients did not have the lethal form of junctional epidermolysis bullosa but, as adults, displayed the milder generalized atrophic benign epidermolysis bullosa variant. There was undetectable laminin 5 staining at the dermal-epidermal junction using an antibody to the β3 chain, but faintly positive α3 and γ2 chain labeling, and there was variable hypoplasia of hemidesmosomes. To explain the milder recessive dystrophic epidermolysis bullosa and junctional epidermolysis bullosa phenotypes in these families, reverse transcription-polymerase chain reaction, using RNA extracted from frozen skin, was able to provide evidence for some rescue of mutant mRNA transcripts with restoration of the open- reading frame. In the recessive dystrophic epidermolysis bullosa patients, transcripts containing in-frame skipping of exon 19 of COL7A1 in the cDNA were detected, and in the junctional epidermolysis bullosa patients transcripts with in-frame skipping of exon 17 of LAMB3 were identified. The truncated proteins encoded by these transcripts are expected to lack certain critical domains involved in cell-matrix attachment, but may still be able to contribute to adhesion thereby moderating the severity of the skin blistering. This study shows the limitations in predicting phenotype in epidermolysis bullosa solely based on mutation analysis of genomic DNA and emphasizes the importance of immunohistochemistry, electron microscopy, and mRNA assessment as parallel investigations.
Original languageEnglish
Pages (from-to)314-321
Number of pages8
JournalJournal of Investigative Dermatology
DOIs
Publication statusPublished - 1 Jan 1999
Externally publishedYes

Fingerprint

Junctional Epidermolysis Bullosa
Frameshift Mutation
Epidermolysis Bullosa Dystrophica
Exons
Collagen Type VII
Skin
Mutation
Messenger RNA
Gene encoding
Biopsy
Phenotype
Polymerase chain reaction
DNA
Transcription
Labeling
Electron microscopy
Restoration
Hemidesmosomes
Epidermolysis Bullosa
Adhesion

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Dermatology
  • Cell Biology

Cite this

McGrath, John A. ; Ashton, Gabrielle H.S. ; Mellerio, Jemima E. ; Salas-Alanis, Julio Cesar ; Swensson, Ole ; McMillan, James R. ; Eady, Robin A.J. / Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations. In: Journal of Investigative Dermatology. 1999 ; pp. 314-321.
@article{459a97ff0ea14067a1031aa1f7fdf7e8,
title = "Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations",
abstract = "Non-sense mutations on both alleles of either the type VII collagen gene (COL7A1) or the genes encoding laminin 5 (LAMA3, LAMB3, or LAMC2) usually result in clinically severe forms of recessive dystrophic or junctional epidermolysis bullosa, respectively. In this study we assessed two unrelated families whose mutations in genomic DNA predicted severe recessive dystrophic epidermolysis bullosa or junctional epidermolysis bullosa phenotypes but in whom the manifestations were milder than expected. The recessive dystrophic epidermolysis bullosa patients had a homozygous single base-pair frameshift mutation in exon 19 of COL7A1 (2470insG). Clinically, there was generalized blistering but only mild scarring. Skin biopsy revealed positive type VII collagen immunoreactivity and recognizable anchoring fibrils. The junctional epidermolysis bullosa patients were compound heterozygotes for a frameshift/non-sense combination of mutations in exons 3 and 17 of LAMB3 (29insC/Q834X). These patients did not have the lethal form of junctional epidermolysis bullosa but, as adults, displayed the milder generalized atrophic benign epidermolysis bullosa variant. There was undetectable laminin 5 staining at the dermal-epidermal junction using an antibody to the β3 chain, but faintly positive α3 and γ2 chain labeling, and there was variable hypoplasia of hemidesmosomes. To explain the milder recessive dystrophic epidermolysis bullosa and junctional epidermolysis bullosa phenotypes in these families, reverse transcription-polymerase chain reaction, using RNA extracted from frozen skin, was able to provide evidence for some rescue of mutant mRNA transcripts with restoration of the open- reading frame. In the recessive dystrophic epidermolysis bullosa patients, transcripts containing in-frame skipping of exon 19 of COL7A1 in the cDNA were detected, and in the junctional epidermolysis bullosa patients transcripts with in-frame skipping of exon 17 of LAMB3 were identified. The truncated proteins encoded by these transcripts are expected to lack certain critical domains involved in cell-matrix attachment, but may still be able to contribute to adhesion thereby moderating the severity of the skin blistering. This study shows the limitations in predicting phenotype in epidermolysis bullosa solely based on mutation analysis of genomic DNA and emphasizes the importance of immunohistochemistry, electron microscopy, and mRNA assessment as parallel investigations.",
author = "McGrath, {John A.} and Ashton, {Gabrielle H.S.} and Mellerio, {Jemima E.} and Salas-Alanis, {Julio Cesar} and Ole Swensson and McMillan, {James R.} and Eady, {Robin A.J.}",
year = "1999",
month = "1",
day = "1",
doi = "10.1046/j.1523-1747.1999.00709.x",
language = "English",
pages = "314--321",
journal = "Journal of Investigative Dermatology",
issn = "0022-202X",
publisher = "Nature Publishing Group",

}

Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations. / McGrath, John A.; Ashton, Gabrielle H.S.; Mellerio, Jemima E.; Salas-Alanis, Julio Cesar; Swensson, Ole; McMillan, James R.; Eady, Robin A.J.

In: Journal of Investigative Dermatology, 01.01.1999, p. 314-321.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Moderation of phenotypic severity in dystrophic and junctional forms of epidermolysis bullosa through in-frame skipping of exons containing non-sense or frameshift mutations

AU - McGrath, John A.

AU - Ashton, Gabrielle H.S.

AU - Mellerio, Jemima E.

AU - Salas-Alanis, Julio Cesar

AU - Swensson, Ole

AU - McMillan, James R.

AU - Eady, Robin A.J.

PY - 1999/1/1

Y1 - 1999/1/1

N2 - Non-sense mutations on both alleles of either the type VII collagen gene (COL7A1) or the genes encoding laminin 5 (LAMA3, LAMB3, or LAMC2) usually result in clinically severe forms of recessive dystrophic or junctional epidermolysis bullosa, respectively. In this study we assessed two unrelated families whose mutations in genomic DNA predicted severe recessive dystrophic epidermolysis bullosa or junctional epidermolysis bullosa phenotypes but in whom the manifestations were milder than expected. The recessive dystrophic epidermolysis bullosa patients had a homozygous single base-pair frameshift mutation in exon 19 of COL7A1 (2470insG). Clinically, there was generalized blistering but only mild scarring. Skin biopsy revealed positive type VII collagen immunoreactivity and recognizable anchoring fibrils. The junctional epidermolysis bullosa patients were compound heterozygotes for a frameshift/non-sense combination of mutations in exons 3 and 17 of LAMB3 (29insC/Q834X). These patients did not have the lethal form of junctional epidermolysis bullosa but, as adults, displayed the milder generalized atrophic benign epidermolysis bullosa variant. There was undetectable laminin 5 staining at the dermal-epidermal junction using an antibody to the β3 chain, but faintly positive α3 and γ2 chain labeling, and there was variable hypoplasia of hemidesmosomes. To explain the milder recessive dystrophic epidermolysis bullosa and junctional epidermolysis bullosa phenotypes in these families, reverse transcription-polymerase chain reaction, using RNA extracted from frozen skin, was able to provide evidence for some rescue of mutant mRNA transcripts with restoration of the open- reading frame. In the recessive dystrophic epidermolysis bullosa patients, transcripts containing in-frame skipping of exon 19 of COL7A1 in the cDNA were detected, and in the junctional epidermolysis bullosa patients transcripts with in-frame skipping of exon 17 of LAMB3 were identified. The truncated proteins encoded by these transcripts are expected to lack certain critical domains involved in cell-matrix attachment, but may still be able to contribute to adhesion thereby moderating the severity of the skin blistering. This study shows the limitations in predicting phenotype in epidermolysis bullosa solely based on mutation analysis of genomic DNA and emphasizes the importance of immunohistochemistry, electron microscopy, and mRNA assessment as parallel investigations.

AB - Non-sense mutations on both alleles of either the type VII collagen gene (COL7A1) or the genes encoding laminin 5 (LAMA3, LAMB3, or LAMC2) usually result in clinically severe forms of recessive dystrophic or junctional epidermolysis bullosa, respectively. In this study we assessed two unrelated families whose mutations in genomic DNA predicted severe recessive dystrophic epidermolysis bullosa or junctional epidermolysis bullosa phenotypes but in whom the manifestations were milder than expected. The recessive dystrophic epidermolysis bullosa patients had a homozygous single base-pair frameshift mutation in exon 19 of COL7A1 (2470insG). Clinically, there was generalized blistering but only mild scarring. Skin biopsy revealed positive type VII collagen immunoreactivity and recognizable anchoring fibrils. The junctional epidermolysis bullosa patients were compound heterozygotes for a frameshift/non-sense combination of mutations in exons 3 and 17 of LAMB3 (29insC/Q834X). These patients did not have the lethal form of junctional epidermolysis bullosa but, as adults, displayed the milder generalized atrophic benign epidermolysis bullosa variant. There was undetectable laminin 5 staining at the dermal-epidermal junction using an antibody to the β3 chain, but faintly positive α3 and γ2 chain labeling, and there was variable hypoplasia of hemidesmosomes. To explain the milder recessive dystrophic epidermolysis bullosa and junctional epidermolysis bullosa phenotypes in these families, reverse transcription-polymerase chain reaction, using RNA extracted from frozen skin, was able to provide evidence for some rescue of mutant mRNA transcripts with restoration of the open- reading frame. In the recessive dystrophic epidermolysis bullosa patients, transcripts containing in-frame skipping of exon 19 of COL7A1 in the cDNA were detected, and in the junctional epidermolysis bullosa patients transcripts with in-frame skipping of exon 17 of LAMB3 were identified. The truncated proteins encoded by these transcripts are expected to lack certain critical domains involved in cell-matrix attachment, but may still be able to contribute to adhesion thereby moderating the severity of the skin blistering. This study shows the limitations in predicting phenotype in epidermolysis bullosa solely based on mutation analysis of genomic DNA and emphasizes the importance of immunohistochemistry, electron microscopy, and mRNA assessment as parallel investigations.

U2 - 10.1046/j.1523-1747.1999.00709.x

DO - 10.1046/j.1523-1747.1999.00709.x

M3 - Article

SP - 314

EP - 321

JO - Journal of Investigative Dermatology

JF - Journal of Investigative Dermatology

SN - 0022-202X

ER -