- Email: [email protected]
Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene
Journal of Clinical Neuroscience xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Case Report
Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene Clinton Turner a,⇑, Rachael Mein b, Cynthia Sharpe c, Donald R. Love d a
Histopathology, LabPLUS, Auckland City Hospital, Post Office Box 110031, Auckland 1148, New Zealand DNA Laboratory, Guy’s Hospital, London, UK c Neurology, Starship Children’s Hospital, Auckland, New Zealand d Diagnostic Genetics, LabPLUS, Auckland, New Zealand b
a r t i c l e
i n f o
Article history: Received 15 February 2015 Accepted 11 April 2015 Available online xxxx Keywords: Immunohistochemistry Laminin-2 Merosin deficient congenital muscular dystrophy Mutation
a b s t r a c t Merosin deficient congenital muscular dystrophy (MDC1A) is an autosomal recessive disorder characterized by mutations in the LAMA2 gene at chromosome 6q22-23. This gene spans 65 exons and encodes the a2 chain subunit of laminin-2. A variety of deletions, missense, nonsense and splice site mutations have been described in the LAMA2 gene, with resultant MDC1A. We describe a novel LAMA2 homozygous sequence variant in a Samoan patient with MDC1A and confirm its pathogenic effect with merosin immunohistochemistry on skeletal muscle biopsy. The likely effect of the sequence variant is modeled using in silico analysis. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Merosin deficient congenital muscular dystrophy (MDC1A) was the first congenital muscular dystrophy to be separately described and have its genetic basis (mutation in LAMA2) determined [1,2]. At birth, or soon after, affected infants present with hypotonia, failure to thrive, respiratory difficulty, contractures and feeding problems. From 6 months of age, characteristic MRI changes may also be seen. Whilst cognitive function is usually normal, a small proportion of patients have mental retardation or epilepsy [3]. MDC1A has been regarded as the most common congenital muscular dystrophy in Western countries, accounting for 30–40% of congenital muscular dystrophies [4]. However, a more recent study found MDC1A to be the third most common congenital muscular dystrophy in the referral cohort [5]. 2. Case report A male infant of Samoan ethnicity, born at 41 + 5 weeks gestation by cesarean section due to failure to progress, was noted to be hypotonic at 1 week of age. When seen by a pediatric neurologist, he was found to have reduced movement, central hypotonia and contractures of both the wrists and ankles. His serum creatine ⇑ Corresponding author. Tel.: +64 9307 4949. E-mail address: [email protected] (C. Turner).
kinase levels around this time ranged between 3780 and 5841 U/L. A variety of metabolic investigations were normal. An MRI at 7 weeks of age demonstrated T2-weighted hyperintense and fluid-attenuated inversion recovery/T1-weighted hypointense white matter changes in the frontal and parietal white matter. Given the MRI changes and clinical phenotype, leukocyte DNA was subjected to gene mutation analysis of the a2 chain subunit of laminin-2 (LAMA2). Mutation screening of LAMA2 was performed by DNA sequencing of 65 amplicons covering the coding exons of LAMA2 using standard Sanger sequencing techniques. This detected a novel homozygous sequence variant, c. 7862G>T (p.Gly2621Val), in exon 56. Given the novelty of this variant, in silico analyses were performed using online bioinformatic programs to predict the consequences at the protein and transcriptional levels (Table 1). Six of the eight protein analysis programs predicted that the variant (p.Gly2621Val) would likely be disease-causing. Interestingly, two of three transcript analysis programs suggested that the variant could also create a splice donor site, and hence would give rise to a misspliced transcript with the formal mutation description of c.7861_7898del; p.(Gly2621Hisfs*8). The effect of this predicted frameshift mutation is a LAMA2 protein in which the 502 amino acids at the carboxyl-terminal are replaced with seven amino acids. Therefore, if there were no effect at the transcript level then the missense mutation may have a deleterious effect, but if there
http://dx.doi.org/10.1016/j.jocn.2015.04.016 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016
2
Case Report / Journal of Clinical Neuroscience xxx (2015) xxx–xxx
Table 1 In silico analyses of the LAMA2 gene* mutation Protein prediction programs PolyPhen-2** [6] Mutation taster [7] Probably damaging (Scores: 1.000; 1.000)
Disease-causing (P: 0.999)
Splice site prediction programs Alternative Splice Site Predictor [14] Cryptic donor site (Score: 7.274)
Mutation assessor [8] (functional impact) Medium
I-MUTANT 3.0 [9]
PMut [10]
MutPred [11]
SNPs&GO [12]
SIFT [13]
Disease (RI: 3)
Pathological (RS: 3)
Deleterious Pdel: 0.942
Neutral (RI: 8)
Not tolerated (SR***: 0.31)
Splice Site Prediction by Neural Network [15] Cryptic donor site (Score: 0.89)
ESE Finder [16,17] No effect
* The Reference Sequence (RefSeq) accession numbers for the transcript and protein sequences that were used for querying the protein prediction programmes were NM_000426.3 and NP_000417.2, respectively. The relevant Universal Protein Resource (Uniprot) reference for the LAMA2 protein was P24043. The protein prediction programmes were queried using the above references, with the LAMA2 gene mutation formally described as c.7862G>T and p.Gly2621Val. ** Scores relate to predictions based on HumDiv and HumVar models. The former refers to training and testing a prediction model based on a compilation of all damaging alleles with known effects on the molecular function causing human Mendelian diseases. The latter refers to training and testing a prediction model based on a compilation of human disease-causing mutations without annotated involvement in disease, which are treated as non-damaging. *** SR is the fraction of sequences that contain one of the basic amino acids. With respect to SR, a low fraction indicates the position is either severely gapped or unalignable and has little information, therefore poor predictions are expected at these positions. P = probability value, Pdel = probability of a deleterious mutation, RI = reliability index, RS = reliability score.
were an effect at the transcript level, then translation would give rise to a prematurely terminated protein. A subsequent biopsy of gastrocnemius showed dystrophic features with marked fibrosis and extensive fatty infiltration of the muscle (Fig. 1A). A stain for merosin (Novocastra Mer3 antibody; Leica Biosystems, Nussloch, Germany) showed a complete loss of merosin staining, indicating a loss of merosin protein and supporting the likely pathogenic nature of the homozygous sequence variant (Fig. 1C). 3. Discussion
Fig. 1. Histological features of the muscle biopsy. (A) Haematoxylin and eosin stain ( 400 magnification) showing dystrophic features with extensive fatty infiltration, fibrosis, fiber atrophy and fiber hypertrophy. (B) Spectrin immunohistochemistry ( 400 magnification) confirming normal antigenicity of the intact muscle fibers. (C) Merosin immunohistochemistry ( 200 magnification) showing complete loss of staining around muscle fibers.
The laminins are a family of trimeric basement membrane glycoproteins that comprise a combination of five genetically distinct a-chains, three b-chains and two c-chains [18]. The main heterotrimers in skeletal muscle are laminin-2 (a2b1c1) and laminin-4 (a2b2c1) [19]. Both trimers contain the a2 chain encoded by the LAMA2 gene which binds to a-dystroglycan, thereby linking the cell membrane to the extracellular matrix [19]. An absence of laminin a2 due to a mutation results in a loss of or defective function of laminin-2 and laminin-4, with consequential poor myofibre adhesion, increased sarcolemmal fragility and sensitivity to apoptosis [20]. To date, at least 90 different LAMA2 gene mutations have been described, which include nonsense, missense, deletion and splice site mutations. A summary of mutations is available at www. dmd.nl/LAMA2_seqvar.html. Mutational testing of the LAMA2 gene for MDC1A can be difficult given the large size of the gene, the lack of mutation hotspots, and the large number of different mutations identified to date. Therefore, immunohistochemical analysis of protein expression in muscle biopsies of patients with suspected MDC1A can be useful as a screening tool, prior to expensive genetic analyses. It may also be used, as in this patient, to confirm a loss of protein expression following the identification of a novel sequence variant. This case report outlines a novel mutation resulting in MDC1A in a Samoan infant. We highlight the usefulness of immunohistochemistry for quickly and economically confirming the significance of a novel genetic variation. A formal neuropsychological evaluation has not yet been performed on this patient. At 4 and a half years of age he has motor delays, as is expected for MDC1A. However, he has a greater language and cognitive delay than usual, with only four words (all names) in his vocabulary at present.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016
Case Report / Journal of Clinical Neuroscience xxx (2015) xxx–xxx
Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
References [1] Tomé FM, Evangelista T, Leclerc A, et al. Congenital muscular dystrophy with merosin deficiency. C R Acad Sci III Sci Vie 1994;317:351–7. [2] Helbling-Leclerc A, Zhang X, Topaloglu H, et al. Mutations in the laminin alpha 2-chain gene (LAMA2) cause merosin-deficient congenital muscular dystrophy. Nat Genet 1995;11:216–8. [3] Echenne B, Rivier F, Jellali AJ, et al. Merosin positive congenital muscular dystrophy with mental deficiency, epilepsy and MRI changes in the cerebral white matter. Neuromuscul Disord 1997;7:187–90. [4] Mostacciuolo ML, Miorin M, Martinello F, et al. Genetic epidemiology of congenital muscular dystrophy in a sample from north-east Italy. Hum Genet 1996;97:277–9. [5] Clement EM, Feng L, Mein R, et al. Relative frequency of congenital muscular dystrophy subtypes: analysis of the UK diagnostic service 2001–2008. Neuromuscul Disord 2012;22:522–7. [6] Adzhubei IA, Schmidt S, Peshkin L, et al. A method and server for predicting damaging missense mutations. Nat Methods 2010;7:248–9. [7] Schwarz JM, Rödelsperger C, Schuelke M, et al. MutationTaster evaluates disease-causing potential of sequence alterations. Nat Methods 2010;7:575–6. [8] Reva B, Antipin Y, Sander C. Predicting the functional impact of protein mutations: application to cancer genomics. Nucleic Acids Res 2011;39:e11.
3
[9] Capriotti E, Fariselli P, Casadio R. I-Mutant2.0: predicting stability changes upon mutation from the protein sequence or structure. Nucleic Acids Res 2005;33:W306–10. [10] Ferrer-Costa C, Gelpí JL, Zamakola L, et al. PMUT: a web-based tool for the annotation of pathological mutations on proteins. Bioinformatics 2005;21: 3176–8. [11] Li B, Krishnan VG, Mort ME, et al. Automated inference of molecular mechanisms of disease from amino acid substitutions. Bioinformatics 2009; 25:2744–50. [12] Capriotti E, Calabrese R, Fariselli P, et al. WS-SNPs&GO: a web server for predicting the deleterious effect of human protein variants using functional annotation. BMC Genomics 2013;14:S6. [13] Ng PC, Henikoff S. SIFT: predicting amino acid changes that affect protein function. Nucleic Acids Res 2003;31:3812–4. [14] Wang M, Marín A. Characterization and prediction of alternative splice sites. Gene 2006;366:219–27. [15] Reese MG, Eeckman FH, Kulp D, et al. Improved splice site detection in genie. J Comp Biol 1997;4:311–23. [16] Smith PJ, Zhang C, Wang J, et al. An increased specificity score matrix for the prediction of SF2/ASF-specific exonic splicing enhancers. Hum Mol Genet 2006;15:2490–508. [17] Cartegni L, Wang J, Zhu Z, et al. ESEfinder: a web resource to identify exonic splicing enhancers. Nucleic Acid Res 2003;31:3568–71. [18] Aumailley M, Bruckner-Tuderman L, Carter WG, et al. A simplified laminin nomenclature. Matrix Biol 2005;24:326–32. [19] Zhang X, Vuolteenaho R, Tryggvason K. Structure of the human laminin alpha2-chain gene (LAMA2), which is affected in congenital muscular dystrophy. J Biol Chem 1996;271:27664–9. [20] Van Ry PM, Minogue P, Hodges BL, et al. Laminin-111 improves muscle repair in a mouse model of merosin-deficient congenital muscular dystrophy. Hum Mol Genet 2014;23:383–96.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Case Report
Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene Clinton Turner a,⇑, Rachael Mein b, Cynthia Sharpe c, Donald R. Love d a
Histopathology, LabPLUS, Auckland City Hospital, Post Office Box 110031, Auckland 1148, New Zealand DNA Laboratory, Guy’s Hospital, London, UK c Neurology, Starship Children’s Hospital, Auckland, New Zealand d Diagnostic Genetics, LabPLUS, Auckland, New Zealand b
a r t i c l e
i n f o
Article history: Received 15 February 2015 Accepted 11 April 2015 Available online xxxx Keywords: Immunohistochemistry Laminin-2 Merosin deficient congenital muscular dystrophy Mutation
a b s t r a c t Merosin deficient congenital muscular dystrophy (MDC1A) is an autosomal recessive disorder characterized by mutations in the LAMA2 gene at chromosome 6q22-23. This gene spans 65 exons and encodes the a2 chain subunit of laminin-2. A variety of deletions, missense, nonsense and splice site mutations have been described in the LAMA2 gene, with resultant MDC1A. We describe a novel LAMA2 homozygous sequence variant in a Samoan patient with MDC1A and confirm its pathogenic effect with merosin immunohistochemistry on skeletal muscle biopsy. The likely effect of the sequence variant is modeled using in silico analysis. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Merosin deficient congenital muscular dystrophy (MDC1A) was the first congenital muscular dystrophy to be separately described and have its genetic basis (mutation in LAMA2) determined [1,2]. At birth, or soon after, affected infants present with hypotonia, failure to thrive, respiratory difficulty, contractures and feeding problems. From 6 months of age, characteristic MRI changes may also be seen. Whilst cognitive function is usually normal, a small proportion of patients have mental retardation or epilepsy [3]. MDC1A has been regarded as the most common congenital muscular dystrophy in Western countries, accounting for 30–40% of congenital muscular dystrophies [4]. However, a more recent study found MDC1A to be the third most common congenital muscular dystrophy in the referral cohort [5]. 2. Case report A male infant of Samoan ethnicity, born at 41 + 5 weeks gestation by cesarean section due to failure to progress, was noted to be hypotonic at 1 week of age. When seen by a pediatric neurologist, he was found to have reduced movement, central hypotonia and contractures of both the wrists and ankles. His serum creatine ⇑ Corresponding author. Tel.: +64 9307 4949. E-mail address: [email protected] (C. Turner).
kinase levels around this time ranged between 3780 and 5841 U/L. A variety of metabolic investigations were normal. An MRI at 7 weeks of age demonstrated T2-weighted hyperintense and fluid-attenuated inversion recovery/T1-weighted hypointense white matter changes in the frontal and parietal white matter. Given the MRI changes and clinical phenotype, leukocyte DNA was subjected to gene mutation analysis of the a2 chain subunit of laminin-2 (LAMA2). Mutation screening of LAMA2 was performed by DNA sequencing of 65 amplicons covering the coding exons of LAMA2 using standard Sanger sequencing techniques. This detected a novel homozygous sequence variant, c. 7862G>T (p.Gly2621Val), in exon 56. Given the novelty of this variant, in silico analyses were performed using online bioinformatic programs to predict the consequences at the protein and transcriptional levels (Table 1). Six of the eight protein analysis programs predicted that the variant (p.Gly2621Val) would likely be disease-causing. Interestingly, two of three transcript analysis programs suggested that the variant could also create a splice donor site, and hence would give rise to a misspliced transcript with the formal mutation description of c.7861_7898del; p.(Gly2621Hisfs*8). The effect of this predicted frameshift mutation is a LAMA2 protein in which the 502 amino acids at the carboxyl-terminal are replaced with seven amino acids. Therefore, if there were no effect at the transcript level then the missense mutation may have a deleterious effect, but if there
http://dx.doi.org/10.1016/j.jocn.2015.04.016 0967-5868/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016
2
Case Report / Journal of Clinical Neuroscience xxx (2015) xxx–xxx
Table 1 In silico analyses of the LAMA2 gene* mutation Protein prediction programs PolyPhen-2** [6] Mutation taster [7] Probably damaging (Scores: 1.000; 1.000)
Disease-causing (P: 0.999)
Splice site prediction programs Alternative Splice Site Predictor [14] Cryptic donor site (Score: 7.274)
Mutation assessor [8] (functional impact) Medium
I-MUTANT 3.0 [9]
PMut [10]
MutPred [11]
SNPs&GO [12]
SIFT [13]
Disease (RI: 3)
Pathological (RS: 3)
Deleterious Pdel: 0.942
Neutral (RI: 8)
Not tolerated (SR***: 0.31)
Splice Site Prediction by Neural Network [15] Cryptic donor site (Score: 0.89)
ESE Finder [16,17] No effect
* The Reference Sequence (RefSeq) accession numbers for the transcript and protein sequences that were used for querying the protein prediction programmes were NM_000426.3 and NP_000417.2, respectively. The relevant Universal Protein Resource (Uniprot) reference for the LAMA2 protein was P24043. The protein prediction programmes were queried using the above references, with the LAMA2 gene mutation formally described as c.7862G>T and p.Gly2621Val. ** Scores relate to predictions based on HumDiv and HumVar models. The former refers to training and testing a prediction model based on a compilation of all damaging alleles with known effects on the molecular function causing human Mendelian diseases. The latter refers to training and testing a prediction model based on a compilation of human disease-causing mutations without annotated involvement in disease, which are treated as non-damaging. *** SR is the fraction of sequences that contain one of the basic amino acids. With respect to SR, a low fraction indicates the position is either severely gapped or unalignable and has little information, therefore poor predictions are expected at these positions. P = probability value, Pdel = probability of a deleterious mutation, RI = reliability index, RS = reliability score.
were an effect at the transcript level, then translation would give rise to a prematurely terminated protein. A subsequent biopsy of gastrocnemius showed dystrophic features with marked fibrosis and extensive fatty infiltration of the muscle (Fig. 1A). A stain for merosin (Novocastra Mer3 antibody; Leica Biosystems, Nussloch, Germany) showed a complete loss of merosin staining, indicating a loss of merosin protein and supporting the likely pathogenic nature of the homozygous sequence variant (Fig. 1C). 3. Discussion
Fig. 1. Histological features of the muscle biopsy. (A) Haematoxylin and eosin stain ( 400 magnification) showing dystrophic features with extensive fatty infiltration, fibrosis, fiber atrophy and fiber hypertrophy. (B) Spectrin immunohistochemistry ( 400 magnification) confirming normal antigenicity of the intact muscle fibers. (C) Merosin immunohistochemistry ( 200 magnification) showing complete loss of staining around muscle fibers.
The laminins are a family of trimeric basement membrane glycoproteins that comprise a combination of five genetically distinct a-chains, three b-chains and two c-chains [18]. The main heterotrimers in skeletal muscle are laminin-2 (a2b1c1) and laminin-4 (a2b2c1) [19]. Both trimers contain the a2 chain encoded by the LAMA2 gene which binds to a-dystroglycan, thereby linking the cell membrane to the extracellular matrix [19]. An absence of laminin a2 due to a mutation results in a loss of or defective function of laminin-2 and laminin-4, with consequential poor myofibre adhesion, increased sarcolemmal fragility and sensitivity to apoptosis [20]. To date, at least 90 different LAMA2 gene mutations have been described, which include nonsense, missense, deletion and splice site mutations. A summary of mutations is available at www. dmd.nl/LAMA2_seqvar.html. Mutational testing of the LAMA2 gene for MDC1A can be difficult given the large size of the gene, the lack of mutation hotspots, and the large number of different mutations identified to date. Therefore, immunohistochemical analysis of protein expression in muscle biopsies of patients with suspected MDC1A can be useful as a screening tool, prior to expensive genetic analyses. It may also be used, as in this patient, to confirm a loss of protein expression following the identification of a novel sequence variant. This case report outlines a novel mutation resulting in MDC1A in a Samoan infant. We highlight the usefulness of immunohistochemistry for quickly and economically confirming the significance of a novel genetic variation. A formal neuropsychological evaluation has not yet been performed on this patient. At 4 and a half years of age he has motor delays, as is expected for MDC1A. However, he has a greater language and cognitive delay than usual, with only four words (all names) in his vocabulary at present.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016
Case Report / Journal of Clinical Neuroscience xxx (2015) xxx–xxx
Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.
References [1] Tomé FM, Evangelista T, Leclerc A, et al. Congenital muscular dystrophy with merosin deficiency. C R Acad Sci III Sci Vie 1994;317:351–7. [2] Helbling-Leclerc A, Zhang X, Topaloglu H, et al. Mutations in the laminin alpha 2-chain gene (LAMA2) cause merosin-deficient congenital muscular dystrophy. Nat Genet 1995;11:216–8. [3] Echenne B, Rivier F, Jellali AJ, et al. Merosin positive congenital muscular dystrophy with mental deficiency, epilepsy and MRI changes in the cerebral white matter. Neuromuscul Disord 1997;7:187–90. [4] Mostacciuolo ML, Miorin M, Martinello F, et al. Genetic epidemiology of congenital muscular dystrophy in a sample from north-east Italy. Hum Genet 1996;97:277–9. [5] Clement EM, Feng L, Mein R, et al. Relative frequency of congenital muscular dystrophy subtypes: analysis of the UK diagnostic service 2001–2008. Neuromuscul Disord 2012;22:522–7. [6] Adzhubei IA, Schmidt S, Peshkin L, et al. A method and server for predicting damaging missense mutations. Nat Methods 2010;7:248–9. [7] Schwarz JM, Rödelsperger C, Schuelke M, et al. MutationTaster evaluates disease-causing potential of sequence alterations. Nat Methods 2010;7:575–6. [8] Reva B, Antipin Y, Sander C. Predicting the functional impact of protein mutations: application to cancer genomics. Nucleic Acids Res 2011;39:e11.
3
[9] Capriotti E, Fariselli P, Casadio R. I-Mutant2.0: predicting stability changes upon mutation from the protein sequence or structure. Nucleic Acids Res 2005;33:W306–10. [10] Ferrer-Costa C, Gelpí JL, Zamakola L, et al. PMUT: a web-based tool for the annotation of pathological mutations on proteins. Bioinformatics 2005;21: 3176–8. [11] Li B, Krishnan VG, Mort ME, et al. Automated inference of molecular mechanisms of disease from amino acid substitutions. Bioinformatics 2009; 25:2744–50. [12] Capriotti E, Calabrese R, Fariselli P, et al. WS-SNPs&GO: a web server for predicting the deleterious effect of human protein variants using functional annotation. BMC Genomics 2013;14:S6. [13] Ng PC, Henikoff S. SIFT: predicting amino acid changes that affect protein function. Nucleic Acids Res 2003;31:3812–4. [14] Wang M, Marín A. Characterization and prediction of alternative splice sites. Gene 2006;366:219–27. [15] Reese MG, Eeckman FH, Kulp D, et al. Improved splice site detection in genie. J Comp Biol 1997;4:311–23. [16] Smith PJ, Zhang C, Wang J, et al. An increased specificity score matrix for the prediction of SF2/ASF-specific exonic splicing enhancers. Hum Mol Genet 2006;15:2490–508. [17] Cartegni L, Wang J, Zhu Z, et al. ESEfinder: a web resource to identify exonic splicing enhancers. Nucleic Acid Res 2003;31:3568–71. [18] Aumailley M, Bruckner-Tuderman L, Carter WG, et al. A simplified laminin nomenclature. Matrix Biol 2005;24:326–32. [19] Zhang X, Vuolteenaho R, Tryggvason K. Structure of the human laminin alpha2-chain gene (LAMA2), which is affected in congenital muscular dystrophy. J Biol Chem 1996;271:27664–9. [20] Van Ry PM, Minogue P, Hodges BL, et al. Laminin-111 improves muscle repair in a mouse model of merosin-deficient congenital muscular dystrophy. Hum Mol Genet 2014;23:383–96.
Please cite this article in press as: Turner C et al. Merosin-deficient congenital muscular dystrophy: A novel homozygous mutation in the laminin-2 gene. J Clin Neurosci (2015), http://dx.doi.org/10.1016/j.jocn.2015.04.016