@article {970, title = {A mutation affecting laminin alpha 5 polymerisation gives rise to a syndromic developmental disorder.}, journal = {Development}, volume = {147}, year = {2020}, month = {2020 06 22}, abstract = {

Laminin alpha 5 (LAMA5) is a member of a large family of proteins that trimerise and then polymerise to form a central component of all basement membranes. Consequently, the protein plays an instrumental role in shaping the normal development of the kidney, skin, neural tube, lung and limb, and many other organs and tissues. Pathogenic mutations in some laminins have been shown to cause a range of largely syndromic conditions affecting the competency of the basement membranes to which they contribute. We report the identification of a mutation in the polymerisation domain of LAMA5 in a patient with a complex syndromic disease characterised by defects in kidney, craniofacial and limb development, and by a range of other congenital defects. Using CRISPR-generated mouse models and biochemical assays, we demonstrate the pathogenicity of this variant, showing that the change results in a failure of the polymerisation of α/β/γ laminin trimers. Comparing these phenotypes with those apparent upon gene deletion in mice provides insights into the specific functional importance of laminin polymerisation during development and tissue homeostasis.

}, keywords = {Amino Acid Sequence, Animals, Animals, Newborn, Child, Preschool, Developmental Disabilities, Fetal Development, Fetus, Humans, Hydronephrosis, Infant, Newborn, Kidney, Laminin, Lung, Male, Mice, Mutation, Polymerization, Protein Domains, Syndrome}, issn = {1477-9129}, doi = {10.1242/dev.189183}, author = {Jones, Lynelle K and Lam, Rachel and McKee, Karen K and Aleksandrova, Maya and Dowling, John and Alexander, Stephen I and Mallawaarachchi, Amali and Cottle, Denny L and Short, Kieran M and Pais, Lynn and Miner, Jeffery H and Mallett, Andrew J and Simons, Cas and McCarthy, Hugh and Yurchenco, Peter D and Smyth, Ian M} } @article {544, title = {A presynaptic congenital myasthenic syndrome attributed to a homozygous sequence variant in LAMA5.}, journal = {Ann N Y Acad Sci}, volume = {1413}, year = {2018}, month = {2018 02}, pages = {119-125}, abstract = {

We report a severe defect of neuromuscular transmission in a consanguineous patient with a homozygous variant in the laminin α5 subunit gene (LAMA5). The variant c.8046C > T (p.Arg2659Trp) is rare and has a predicted deleterious effect. The affected individual, who also carries a rare homozygous sequence variant in LAMA1, had normal cognitive function, but magnetic resonance brain imaging showed mild volume loss and periventricular T2 prolongation. Repetitive nerve stimulation at 2 Hz showed 50\% decrement of compound muscle action potential amplitudes but 250\% facilitation immediately after exercise, similar to that seen in Lambert-Eaton myasthenic syndrome. Endplate studies demonstrated a profound reduction of the endplate potential quantal content but normal amplitudes of miniature endplate potentials. Electron microscopy showed endplates with increased postsynaptic folding that were denuded or only partially occupied by small nerve terminals. Expression studies revealed that p.Arg2659Trp caused decreased binding of laminin α5 to SV2A and impaired laminin-521 cell adhesion and cell projection support in primary neuronal cultures. In summary, this report describing severe neuromuscular transmission failure in a patient with a LAMA5 mutation expands the list of phenotypes associated with defects in genes encoding α-laminins.

}, keywords = {Adult, Female, Humans, Lambert-Eaton Myasthenic Syndrome, Laminin, Motor Endplate, Myasthenic Syndromes, Congenital, Synaptic Transmission}, issn = {1749-6632}, doi = {10.1111/nyas.13585}, author = {Maselli, Ricardo A and Arredondo, Juan and V{\'a}zquez, Jessica and Chong, Jessica X and Bamshad, Michael J and Nickerson, Deborah A and Lara, Marian and Ng, Fiona and Lo, Victoria Lee and Pytel, Peter and McDonald, Craig M} } @article {385, title = {Whole-Exome Sequencing Identifies Novel Variants for Tooth Agenesis.}, journal = {J Dent Res}, volume = {97}, year = {2018}, month = {2018 Jan}, pages = {49-59}, abstract = {

Tooth agenesis is a common craniofacial abnormality in humans and represents failure to develop 1 or more permanent teeth. Tooth agenesis is complex, and variations in about a dozen genes have been reported as contributing to the etiology. Here, we combined whole-exome sequencing, array-based genotyping, and linkage analysis to identify putative pathogenic variants in candidate disease genes for tooth agenesis in 10 multiplex Turkish families. Novel homozygous and heterozygous variants in LRP6, DKK1, LAMA3, and COL17A1 genes, as well as known variants in WNT10A, were identified as likely pathogenic in isolated tooth agenesis. Novel variants in KREMEN1 were identified as likely pathogenic in 2 families with suspected syndromic tooth agenesis. Variants in more than 1 gene were identified segregating with tooth agenesis in 2 families, suggesting oligogenic inheritance. Structural modeling of missense variants suggests deleterious effects to the encoded proteins. Functional analysis of an indel variant (c.3607+3_6del) in LRP6 suggested that the predicted resulting mRNA is subject to nonsense-mediated decay. Our results support a major role for WNT pathways genes in the etiology of tooth agenesis while revealing new candidate genes. Moreover, oligogenic cosegregation was suggestive for complex inheritance and potentially complex gene product interactions during development, contributing to improved understanding of the genetic etiology of familial tooth agenesis.

}, keywords = {Anodontia, Female, Genetic Linkage, Genetic Variation, Humans, Intercellular Signaling Peptides and Proteins, Laminin, Low Density Lipoprotein Receptor-Related Protein-6, Male, Membrane Proteins, Mutation, Missense, Pedigree, Real-Time Polymerase Chain Reaction, Turkey, Whole Exome Sequencing, Wnt Proteins}, issn = {1544-0591}, doi = {10.1177/0022034517724149}, author = {Dinckan, N and Du, R and Petty, L E and Coban-Akdemir, Z and Jhangiani, S N and Paine, I and Baugh, E H and Erdem, A P and Kayserili, H and Doddapaneni, H and Hu, J and Muzny, D M and Boerwinkle, E and Gibbs, R A and Lupski, J R and Uyguner, Z O and Below, J E and Letra, A} } @article {362, title = {Presynaptic congenital myasthenic syndrome with a homozygous sequence variant in LAMA5 combines myopia, facial tics, and failure of neuromuscular transmission.}, journal = {Am J Med Genet A}, volume = {173}, year = {2017}, month = {2017 Aug}, pages = {2240-2245}, abstract = {

Defects in genes encoding the isoforms of the laminin alpha subunit have been linked to various phenotypic manifestations, including brain malformations, muscular dystrophy, ocular defects, cardiomyopathy, and skin abnormalities. We report here a severe defect of neuromuscular transmission in a consanguineous patient with a homozygous variant in the laminin alpha-5 subunit gene (LAMA5). The variant c.8046C>T (p.Arg2659Trp) is rare and has a predicted deleterious effect. The affected individual, who also carries a rare homozygous sequence variant in LAMA1, had muscle weakness, myopia, and facial tics. Magnetic resonance imaging of brain showed mild volume loss and periventricular T2 prolongation. Repetitive nerve stimulation revealed 50\% decrement of compound muscle action potential amplitudes and 250\% facilitation immediately after exercise, Endplate studies identified a profound reduction of the endplate potential quantal content and endplates with normal postsynaptic folding that were denuded or partially occupied by small nerve terminals. Expression studies revealed that p.Arg2659Trp caused decreased binding of laminin alpha-5 to SV2A and impaired laminin-521 cell-adhesion and cell projection support in primary neuronal cultures. In summary, this report describing severe neuromuscular transmission failure in a patient with a LAMA5 mutation expands the list of phenotypes associated with defects in genes encoding alpha-laminins.

}, keywords = {Adult, Face, Female, Homozygote, Humans, Laminin, Myasthenic Syndromes, Congenital, Myopia, Neuromuscular Junction Diseases, Tics, Young Adult}, issn = {1552-4833}, doi = {10.1002/ajmg.a.38291}, author = {Maselli, Ricardo A and Arredondo, Juan and V{\'a}zquez, Jessica and Chong, Jessica X and Bamshad, Michael J and Nickerson, Deborah A and Lara, Marian and Ng, Fiona and Lo, Victoria L and Pytel, Peter and McDonald, Craig M} } @article {228, title = {Mutations in LAMA1 cause cerebellar dysplasia and cysts with and without retinal dystrophy.}, journal = {Am J Hum Genet}, volume = {95}, year = {2014}, month = {2014 Aug 07}, pages = {227-34}, abstract = {

Cerebellar dysplasia with cysts (CDC) is an imaging finding typically seen in combination with cobblestone cortex and congenital muscular dystrophy in individuals with dystroglycanopathies. More recently, CDC was reported in seven children without neuromuscular involvement (Poretti-Boltshauser syndrome). Using a combination of homozygosity mapping and whole-exome sequencing, we identified biallelic mutations in LAMA1 as the cause of CDC in seven affected individuals (from five families) independent from those included in the phenotypic description of Poretti-Boltshauser syndrome. Most of these individuals also have high myopia, and some have retinal dystrophy and patchy increased T2-weighted fluid-attenuated inversion recovery (T2/FLAIR) signal in cortical white matter. In one additional family, we identified two siblings who have truncating LAMA1 mutations in combination with retinal dystrophy and mild cerebellar dysplasia without cysts, indicating that cysts are not an obligate feature associated with loss of LAMA1 function. This work expands the phenotypic spectrum associated with the lamininopathy disorders and highlights the tissue-specific roles played by different laminin-encoding genes.

}, keywords = {Adult, Alleles, Base Sequence, Cerebellar Cortex, Cerebellar Diseases, Child, Child, Preschool, Cysts, Exome, Female, Humans, Laminin, Male, Muscular Dystrophies, Retinal Dystrophies, Sequence Analysis, DNA, Young Adult}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.07.007}, author = {Aldinger, Kimberly A and Mosca, Stephen J and T{\'e}treault, Martine and Dempsey, Jennifer C and Ishak, Gisele E and Hartley, Taila and Phelps, Ian G and Lamont, Ryan E and O{\textquoteright}Day, Diana R and Basel, Donald and Gripp, Karen W and Baker, Laura and Stephan, Mark J and Bernier, Francois P and Boycott, Kym M and Majewski, Jacek and Parboosingh, Jillian S and Innes, A Micheil and Doherty, Dan} } @article {309, title = {Mutations in LAMB1 cause cobblestone brain malformation without muscular or ocular abnormalities.}, journal = {Am J Hum Genet}, volume = {92}, year = {2013}, month = {2013 Mar 07}, pages = {468-74}, abstract = {

Cobblestone brain malformation (COB) is a neuronal migration disorder characterized by protrusions of neurons beyond the first cortical layer at the pial surface of the brain. It is usually seen in association with dystroglycanopathy types of congenital muscular dystrophies (CMDs) and ocular abnormalities termed muscle-eye-brain disease. Here we report homozygous deleterious mutations in LAMB1, encoding laminin subunit beta-1, in two families with autosomal-recessive COB. Affected individuals displayed a constellation of brain malformations including cortical gyral and white-matter signal abnormalities, severe cerebellar dysplasia, brainstem hypoplasia, and occipital encephalocele, but they had less apparent ocular or muscular abnormalities than are typically observed in COB. LAMB1 is localized to the pial basement membrane, suggesting that defective connection between radial glial cells and the pial surface mediated by LAMB1 leads to this malformation.

}, keywords = {Basement Membrane, Brain, Cerebellum, Cerebral Cortex, Encephalocele, Female, Genetic Predisposition to Disease, Homozygote, Humans, Laminin, Male, Muscular Dystrophies, Nervous System Malformations, Neuroglia, Neurons, Sequence Deletion, Walker-Warburg Syndrome}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2013.02.005}, author = {Radmanesh, Farid and {\c C}a{\u g}layan, Ahmet Okay and Silhavy, Jennifer L and Yilmaz, Cahide and Cantagrel, Vincent and Omar, Tarek and Rosti, Basak and Kaymak{\c c}alan, Hande and Gabriel, Stacey and Li, Mingfeng and {\v S}estan, Nenad and Bilguvar, Kaya and Dobyns, William B and Zaki, Maha S and G{\"u}nel, Murat and Gleeson, Joseph G} }