@article {814, title = {Mutations in MYLPF Cause a Novel Segmental Amyoplasia that Manifests as Distal Arthrogryposis.}, journal = {Am J Hum Genet}, volume = {107}, year = {2020}, month = {2020 08 06}, pages = {293-310}, abstract = {

We identified ten persons in six consanguineous families with distal arthrogryposis (DA) who had congenital contractures, scoliosis, and short stature. Exome sequencing revealed that each affected person was homozygous for one of two different rare variants (c.470G>T [p.Cys157Phe] or c.469T>C [p.Cys157Arg]) affecting the same residue of myosin light chain, phosphorylatable, fast skeletal muscle (MYLPF). In a seventh family, a c.487G>A (p.Gly163Ser) variant in MYLPF arose de novo in a father, who transmitted it to his son. In an eighth family comprised of seven individuals with dominantly inherited DA, a c.98C>T (p.Ala33Val) variant segregated in all four persons tested. Variants in MYLPF underlie both dominant and recessively inherited DA. Mylpf protein models suggest that the residues associated with dominant DA interact with myosin whereas the residues altered in families with recessive DA only indirectly impair this interaction. Pathological and histological exam of a foot amputated from an affected child revealed complete absence of skeletal muscle (i.e., segmental amyoplasia). To investigate the mechanism for this finding, we generated an animal model for partial MYLPF impairment by knocking out zebrafish mylpfa. The mylpfa mutant had reduced trunk contractile force and complete pectoral fin paralysis, demonstrating that mylpf impairment most severely affects limb movement. mylpfa mutant muscle weakness was most pronounced in an appendicular muscle and was explained by reduced myosin activity and fiber degeneration. Collectively, our findings demonstrate that partial loss of MYLPF function can lead to congenital contractures, likely as a result of degeneration of skeletal muscle in the distal limb.

}, keywords = {Adolescent, Amino Acid Sequence, Animals, Arthrogryposis, Child, Contracture, Extremities, Female, Humans, Male, Muscle, Skeletal, Musculoskeletal Abnormalities, Mutation, Myosin Light Chains, Myosins, Pedigree, Young Adult, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.06.014}, author = {Chong, Jessica X and Talbot, Jared C and Teets, Emily M and Previs, Samantha and Martin, Brit L and Shively, Kathryn M and Marvin, Colby T and Aylsworth, Arthur S and Saadeh-Haddad, Reem and Schatz, Ulrich A and Inzana, Francesca and Ben-Omran, Tawfeg and Almusafri, Fatima and Al-Mulla, Mariam and Buckingham, Kati J and Harel, Tamar and Mor-Shaked, Hagar and Radhakrishnan, Periyasamy and Girisha, Katta M and Nayak, Shalini S and Shukla, Anju and Dieterich, Klaus and Faure, Julien and Rendu, John and Capri, Yline and Latypova, X{\'e}nia and Nickerson, Deborah A and Warshaw, David M and Janssen, Paul M L and Amacher, Sharon L and Bamshad, Michael J} } @article {799, title = {NEMF mutations that impair ribosome-associated quality control are associated with neuromuscular disease.}, journal = {Nat Commun}, volume = {11}, year = {2020}, month = {2020 09 15}, pages = {4625}, abstract = {

A hallmark of neurodegeneration is defective protein quality control. The E3 ligase Listerin (LTN1/Ltn1) acts in a specialized protein quality control pathway-Ribosome-associated Quality Control (RQC)-by mediating proteolytic targeting of incomplete polypeptides produced by ribosome stalling, and Ltn1 mutation leads to neurodegeneration in mice. Whether neurodegeneration results from defective RQC and whether defective RQC contributes to human disease have remained unknown. Here we show that three independently-generated mouse models with mutations in a different component of the RQC complex, NEMF/Rqc2, develop progressive motor neuron degeneration. Equivalent mutations in yeast Rqc2 selectively interfere with its ability to modify aberrant translation products with C-terminal tails which assist with RQC-mediated protein degradation, suggesting a pathomechanism. Finally, we identify NEMF mutations expected to interfere with function in patients from seven families presenting juvenile neuromuscular disease. These uncover NEMF{\textquoteright}s role in translational homeostasis in the nervous system and implicate RQC dysfunction in causing neurodegeneration.

}, keywords = {Amino Acid Sequence, Animals, Female, Humans, Male, Mice, Mice, Knockout, Mutation, Neuromuscular Diseases, Proteolysis, Ribosomes, RNA-Binding Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment}, issn = {2041-1723}, doi = {10.1038/s41467-020-18327-6}, author = {Martin, Paige B and Kigoshi-Tansho, Yu and Sher, Roger B and Ravenscroft, Gianina and Stauffer, Jennifer E and Kumar, Rajesh and Yonashiro, Ryo and M{\"u}ller, Tina and Griffith, Christopher and Allen, William and Pehlivan, Davut and Harel, Tamar and Zenker, Martin and Howting, Denise and Schanze, Denny and Faqeih, Eissa A and Almontashiri, Naif A M and Maroofian, Reza and Houlden, Henry and Mazaheri, Neda and Galehdari, Hamid and Douglas, Ganka and Posey, Jennifer E and Ryan, Monique and Lupski, James R and Laing, Nigel G and Joazeiro, Claudio A P and Cox, Gregory A} } @article {767, title = {Recurrent De Novo NAHR Reciprocal Duplications in the ATAD3 Gene Cluster Cause a Neurogenetic Trait with Perturbed Cholesterol and Mitochondrial Metabolism.}, journal = {Am J Hum Genet}, volume = {106}, year = {2020}, month = {2020 02 06}, pages = {272-279}, abstract = {

Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data.

}, keywords = {Amino Acid Sequence, ATPases Associated with Diverse Cellular Activities, Brain Diseases, Cardiomyopathies, Cholesterol, Corneal Opacity, DNA Copy Number Variations, Female, Gene Duplication, Gene Rearrangement, Homologous Recombination, Humans, Infant, Infant, Newborn, Male, Membrane Proteins, Mitochondria, Mitochondrial Diseases, Mitochondrial Proteins, Muscle Hypotonia, Mutation, Protein Conformation, Seizures, Sequence Homology}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.01.007}, author = {Gunning, Adam C and Strucinska, Klaudia and Mu{\~n}oz Oreja, Mikel and Parrish, Andrew and Caswell, Richard and Stals, Karen L and Durigon, Romina and Durlacher-Betzer, Karina and Cunningham, Mitchell H and Grochowski, Christopher M and Baptista, Julia and Tysoe, Carolyn and Baple, Emma and Lahiri, Nayana and Homfray, Tessa and Scurr, Ingrid and Armstrong, Catherine and Dean, John and Fernandez Pelayo, Uxoa and Jones, Aleck W E and Taylor, Robert W and Misra, Vinod K and Yoon, Wan Hee and Wright, Caroline F and Lupski, James R and Spinazzola, Antonella and Harel, Tamar and Holt, Ian J and Ellard, Sian} } @article {24, title = {Bi-allelic Mutations in PKD1L1 Are Associated with Laterality Defects in Humans.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Oct 06}, pages = {886-893}, abstract = {

Disruption of the establishment of left-right (L-R) asymmetry leads to situs anomalies ranging from situs inversus totalis (SIT) to situs ambiguus (heterotaxy). The genetic causes of laterality defects in humans are highly heterogeneous. Via whole-exome sequencing (WES), we identified homozygous mutations in PKD1L1 from three affected individuals in two unrelated families. PKD1L1 encodes a polycystin-1-like protein and its loss of function is known to cause laterality defects in mouse and medaka fish models. Family 1 had one fetus and one deceased child with heterotaxy and complex congenital heart malformations. WES identified a homozygous splicing mutation, c.6473+2_6473+3delTG, which disrupts the invariant splice donor site in intron 42, in both affected individuals. In the second family, a homozygous c.5072G>C (p.Cys1691Ser) missense mutation was detected in an individual with SIT and congenital heart disease. The p.Cys1691Ser substitution affects a highly conserved cysteine residue and is predicted by molecular modeling to disrupt a disulfide bridge essential for the proper folding of the G protein-coupled receptor proteolytic site (GPS) motif. Damaging effects associated with substitutions of this conserved cysteine residue in the GPS motif have also been reported in other genes, namely GPR56, BAI3, and PKD1 in human and lat-1 in C.~elegans, further supporting the likely pathogenicity of p.Cys1691Ser in PKD1L1. The identification of bi-allelic PKD1L1 mutations recapitulates previous findings regarding phenotypic consequences of loss of function of the orthologous genes in mice and medaka fish and further expands our understanding of genetic contributions to laterality defects in humans.

}, keywords = {Alleles, Amino Acid Motifs, Amino Acid Sequence, Animals, Caenorhabditis elegans, Cysteine, Exome, Female, Fetal Diseases, Functional Laterality, Heart Defects, Congenital, Heterotaxy Syndrome, Homozygote, Humans, Infant, Newborn, Introns, Male, Membrane Proteins, Mice, Middle Aged, Models, Molecular, Mutation, Mutation, Missense, Oryzias, Pedigree, RNA Splicing, Situs Inversus}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.07.011}, author = {Vetrini, Francesco and D{\textquoteright}Alessandro, Lisa C A and Akdemir, Zeynep C and Braxton, Alicia and Azamian, Mahshid S and Eldomery, Mohammad K and Miller, Kathryn and Kois, Chelsea and Sack, Virginia and Shur, Natasha and Rijhsinghani, Asha and Chandarana, Jignesh and Ding, Yan and Holtzman, Judy and Jhangiani, Shalini N and Muzny, Donna M and Gibbs, Richard A and Eng, Christine M and Hanchard, Neil A and Harel, Tamar and Rosenfeld, Jill A and Belmont, John W and Lupski, James R and Yang, Yaping} } @article {75, title = {Monoallelic and Biallelic Variants in EMC1 Identified in Individuals with Global Developmental Delay, Hypotonia, Scoliosis, and Cerebellar Atrophy.}, journal = {Am J Hum Genet}, volume = {98}, year = {2016}, month = {2016 Mar 03}, pages = {562-570}, abstract = {

The paradigm of a single gene associated with one specific phenotype and mode of inheritance has been repeatedly challenged. Genotype-phenotype correlations can often be traced to different mutation types, localization of the variants in distinct protein domains, or the trigger of or escape from nonsense-mediated decay. Using whole-exome sequencing, we identified homozygous variants in EMC1 that segregated with a phenotype of developmental delay, hypotonia, scoliosis, and cerebellar atrophy in three families. In addition, a de novo heterozygous EMC1 variant was seen in an individual with a similar clinical and MRI imaging phenotype. EMC1 encodes a member of the endoplasmic reticulum (ER)-membrane protein complex (EMC), an evolutionarily conserved complex that has been proposed to have multiple roles in ER-associated degradation, ER-mitochondria tethering, and proper assembly of multi-pass transmembrane proteins. Perturbations of protein folding and organelle crosstalk have been implicated in neurodegenerative processes including cerebellar atrophy. We propose EMC1 as a gene in which either biallelic or monoallelic variants might lead to a syndrome including intellectual disability and preferential degeneration of the cerebellum.

}, keywords = {Adolescent, Alleles, Amino Acid Sequence, Atrophy, Cerebellum, Child, Child, Preschool, Developmental Disabilities, Endoplasmic Reticulum-Associated Degradation, Female, Genetic Association Studies, Genetic Variation, Heterozygote, Humans, Magnetic Resonance Imaging, Male, Molecular Sequence Data, Muscle Hypotonia, Mutation, Pedigree, Protein Folding, Proteins, Scoliosis}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.01.011}, author = {Harel, Tamar and Yesil, G{\"o}zde and Bayram, Yavuz and Coban-Akdemir, Zeynep and Charng, Wu-Lin and Karaca, Ender and Al Asmari, Ali and Eldomery, Mohammad K and Hunter, Jill V and Jhangiani, Shalini N and Rosenfeld, Jill A and Pehlivan, Davut and El-Hattab, Ayman W and Saleh, Mohammed A and LeDuc, Charles A and Muzny, Donna and Boerwinkle, Eric and Gibbs, Richard A and Chung, Wendy K and Yang, Yaping and Belmont, John W and Lupski, James R} }