@article {464, title = {Truncating Variants in NAA15 Are Associated with Variable Levels of Intellectual Disability, Autism Spectrum Disorder, and Congenital Anomalies.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 05 03}, pages = {985-994}, abstract = {

N-alpha-acetylation is a common co-translational protein modification that is essential for normal cell function in humans. We previously identified the genetic basis of an X-linked infantile lethal Mendelian disorder involving a c.109T>C (p.Ser37Pro) missense variant in NAA10, which encodes the catalytic subunit of the N-terminal acetyltransferase A (NatA) complex. The auxiliary subunit of the NatA complex, NAA15, is the dimeric binding partner for NAA10. Through a genotype-first approach with whole-exome or genome sequencing (WES/WGS) and targeted sequencing analysis, we identified and phenotypically characterized 38 individuals from 33 unrelated families with 25 different de novo or inherited, dominantly acting likely gene disrupting (LGD) variants in NAA15. Clinical features of affected individuals with LGD variants in NAA15 include variable levels of intellectual disability, delayed speech and motor milestones, and autism spectrum disorder. Additionally, mild craniofacial dysmorphology, congenital cardiac anomalies, and seizures are present in some subjects. RNA analysis in cell lines from two individuals showed degradation of the transcripts with LGD variants, probably as a result of nonsense-mediated decay. Functional assays in yeast confirmed a deleterious effect for two of the LGD variants in NAA15. Further supporting a mechanism of haploinsufficiency, individuals with copy-number variant (CNV) deletions involving NAA15 and surrounding genes can present with mild intellectual disability, mild dysmorphic features, motor delays, and decreased growth. We propose that defects in NatA-mediated N-terminal acetylation (NTA) lead to variable levels of neurodevelopmental disorders in humans, supporting the importance of the NatA complex in normal human development.

}, keywords = {Abnormalities, Multiple, Adolescent, Adult, Autism Spectrum Disorder, Cell Line, Child, Exons, Female, Gene Expression Regulation, Genetic Predisposition to Disease, Genetic Variation, Humans, Intellectual Disability, Male, Middle Aged, Mutation, N-Terminal Acetyltransferase A, N-Terminal Acetyltransferase E, Pedigree, Phenotype, RNA, Messenger, Saccharomyces cerevisiae}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2018.03.004}, author = {Cheng, Hanyin and Dharmadhikari, Avinash V and Varland, Sylvia and Ma, Ning and Domingo, Deepti and Kleyner, Robert and Rope, Alan F and Yoon, Margaret and Stray-Pedersen, Asbj{\o}rg and Posey, Jennifer E and Crews, Sarah R and Eldomery, Mohammad K and Akdemir, Zeynep Coban and Lewis, Andrea M and Sutton, Vernon R and Rosenfeld, Jill A and Conboy, Erin and Agre, Katherine and Xia, Fan and Walkiewicz, Magdalena and Longoni, Mauro and High, Frances A and van Slegtenhorst, Marjon A and Mancini, Grazia M S and Finnila, Candice R and van Haeringen, Arie and den Hollander, Nicolette and Ruivenkamp, Claudia and Naidu, Sakkubai and Mahida, Sonal and Palmer, Elizabeth E and Murray, Lucinda and Lim, Derek and Jayakar, Parul and Parker, Michael J and Giusto, Stefania and Stracuzzi, Emanuela and Romano, Corrado and Beighley, Jennifer S and Bernier, Raphael A and K{\"u}ry, S{\'e}bastien and Nizon, Mathilde and Corbett, Mark A and Shaw, Marie and Gardner, Alison and Barnett, Christopher and Armstrong, Ruth and Kassahn, Karin S and Van Dijck, Anke and Vandeweyer, Geert and Kleefstra, Tjitske and Schieving, Jolanda and Jongmans, Marjolijn J and de Vries, Bert B A and Pfundt, Rolph and Kerr, Bronwyn and Rojas, Samantha K and Boycott, Kym M and Person, Richard and Willaert, Rebecca and Eichler, Evan E and Kooy, R Frank and Yang, Yaping and Wu, Joseph C and Lupski, James R and Arnesen, Thomas and Cooper, Gregory M and Chung, Wendy K and Gecz, Jozef and Stessman, Holly A F and Meng, Linyan and Lyon, Gholson J} } @article {637, title = {Clinically severe CACNA1A alleles affect synaptic function and neurodegeneration differentially.}, journal = {PLoS Genet}, volume = {13}, year = {2017}, month = {2017 Jul}, pages = {e1006905}, abstract = {

Dominant mutations in CACNA1A, encoding the α-1A subunit of the neuronal P/Q type voltage-dependent Ca2+ channel, can cause diverse neurological phenotypes. Rare cases of markedly severe early onset developmental delay and congenital ataxia can be due to de novo CACNA1A missense alleles, with variants affecting the S4 transmembrane segments of the channel, some of which are reported to be loss-of-function. Exome sequencing in five individuals with severe early onset ataxia identified one novel variant (p.R1673P), in a girl with global developmental delay and progressive cerebellar atrophy, and a recurrent, de novo p.R1664Q variant, in four individuals with global developmental delay, hypotonia, and ophthalmologic abnormalities. Given the severity of these phenotypes we explored their functional impact in Drosophila. We previously generated null and partial loss-of-function alleles of cac, the homolog of CACNA1A in Drosophila. Here, we created transgenic wild type and mutant genomic rescue constructs with the two noted conserved point mutations. The p.R1673P mutant failed to rescue cac lethality, displayed a gain-of-function phenotype in electroretinograms (ERG) recorded from mutant clones, and evolved a neurodegenerative phenotype in aging flies, based on ERGs and transmission electron microscopy. In contrast, the p.R1664Q variant exhibited loss of function and failed to develop a neurodegenerative phenotype. Hence, the novel R1673P allele produces neurodegenerative phenotypes in flies and human, likely due to a toxic gain of function.

}, keywords = {Alleles, Animals, Animals, Genetically Modified, Calcium Channels, Cerebellar Ataxia, Child, Child, Preschool, Drosophila melanogaster, Female, Genome, Human, Genome-Wide Association Study, Humans, Male, Microscopy, Electron, Transmission, Mutation, Missense, Neurodegenerative Diseases, Neuroimaging, Phenotype, Point Mutation}, issn = {1553-7404}, doi = {10.1371/journal.pgen.1006905}, author = {Luo, Xi and Rosenfeld, Jill A and Yamamoto, Shinya and Harel, Tamar and Zuo, Zhongyuan and Hall, Melissa and Wierenga, Klaas J and Pastore, Matthew T and Bartholomew, Dennis and Delgado, Mauricio R and Rotenberg, Joshua and Lewis, Richard Alan and Emrick, Lisa and Bacino, Carlos A and Eldomery, Mohammad K and Coban Akdemir, Zeynep and Xia, Fan and Yang, Yaping and Lalani, Seema R and Lotze, Timothy and Lupski, James R and Lee, Brendan and Bellen, Hugo J and Wangler, Michael F} } @article {10, title = {MIPEP recessive variants cause a syndrome of left ventricular non-compaction, hypotonia, and infantile death.}, journal = {Genome Med}, volume = {8}, year = {2016}, month = {2016 Nov 01}, pages = {106}, abstract = {

BACKGROUND: Mitochondrial presequence proteases perform fundamental functions as they process about 70~\% of all mitochondrial preproteins that are encoded in the nucleus and imported posttranslationally. The mitochondrial intermediate presequence protease MIP/Oct1, which carries out precursor processing, has not yet been established to have a role in human disease.

METHODS: Whole exome sequencing was performed on four unrelated probands with left ventricular non-compaction (LVNC), developmental delay (DD), seizures, and severe hypotonia. Proposed pathogenic variants were confirmed by Sanger sequencing or array comparative genomic hybridization. Functional analysis of the identified MIP variants was performed using the model organism Saccharomyces cerevisiae as the protein and its functions are highly conserved from yeast to human.

RESULTS: Biallelic single nucleotide variants (SNVs) or copy number variants (CNVs) in MIPEP, which encodes MIP, were present in all four probands, three of whom had infantile/childhood death. Two patients had compound heterozygous SNVs (p.L582R/p.L71Q and p.E602*/p.L306F) and one patient from a consanguineous family had a homozygous SNV (p.K343E). The fourth patient, identified through the GeneMatcher tool, a part of the Matchmaker Exchange Project, was found to have inherited a paternal SNV (p.H512D) and a maternal CNV (1.4-Mb deletion of 13q12.12) that includes MIPEP. All amino acids affected in the patients{\textquoteright} missense variants are highly conserved from yeast to human and therefore S. cerevisiae was employed for functional analysis (for p.L71Q, p.L306F, and p.K343E). The mutations p.L339F (human p.L306F) and p.K376E (human p.K343E) resulted in a severe decrease of Oct1 protease activity and accumulation of non-processed Oct1 substrates and consequently impaired viability under respiratory growth conditions. The p.L83Q (human p.L71Q) failed to localize to the mitochondria.

CONCLUSIONS: Our findings reveal for the first time the role of the mitochondrial intermediate peptidase in human disease. Loss of MIP function results in a syndrome which consists of LVNC, DD, seizures, hypotonia, and cataracts. Our approach highlights the power of data exchange and the importance of an interrelationship between clinical and research efforts for disease gene discovery.

}, keywords = {Adult, Amino Acid Sequence, Female, Genes, Recessive, Heart Defects, Congenital, Humans, Infant, Infant, Newborn, Male, Metalloendopeptidases, Muscle Hypotonia, Pedigree, Phenotype, Sequence Homology, Amino Acid, Sudden Infant Death, Syndrome}, issn = {1756-994X}, doi = {10.1186/s13073-016-0360-6}, author = {Eldomery, Mohammad K and Akdemir, Zeynep C and V{\"o}gtle, F-Nora and Charng, Wu-Lin and Mulica, Patrycja and Rosenfeld, Jill A and Gambin, Tomasz and Gu, Shen and Burrage, Lindsay C and Al Shamsi, Aisha and Penney, Samantha and Jhangiani, Shalini N and Zimmerman, Holly H and Muzny, Donna M and Wang, Xia and Tang, Jia and Medikonda, Ravi and Ramachandran, Prasanna V and Wong, Lee-Jun and Boerwinkle, Eric and Gibbs, Richard A and Eng, Christine M and Lalani, Seema R and Hertecant, Jozef and Rodenburg, Richard J and Abdul-Rahman, Omar A and Yang, Yaping and Xia, Fan and Wang, Meng C and Lupski, James R and Meisinger, Chris and Sutton, V Reid} } @article {21, title = {Recurrent De Novo and Biallelic Variation of ATAD3A, Encoding a Mitochondrial Membrane Protein, Results in Distinct Neurological Syndromes.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Oct 06}, pages = {831-845}, abstract = {

ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane protein implicated in mitochondrial dynamics, nucleoid organization, protein translation, cell growth, and cholesterol metabolism. We identified a recurrent de novo ATAD3A c.1582C>T (p.Arg528Trp) variant by whole-exome sequencing (WES) in five unrelated individuals with a core phenotype of global developmental delay, hypotonia, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. We also describe two families with biallelic variants in ATAD3A, including a homozygous variant in two siblings, and biallelic ATAD3A deletions mediated by nonallelic homologous recombination (NAHR) between ATAD3A and gene family members ATAD3B and ATAD3C. Tissue-specific overexpression of bor, the Drosophila mutation homologous to the human c.1582C>T (p.Arg528Trp) variant, resulted in a dramatic decrease in mitochondrial content, aberrant mitochondrial morphology, and increased autophagy. Homozygous null bor larvae showed a significant decrease of mitochondria, while overexpression of bor resulted in larger, elongated mitochondria. Finally, fibroblasts of an affected individual exhibited increased mitophagy. We conclude that the p.Arg528Trp variant functions through a dominant-negative mechanism that results in small mitochondria that trigger mitophagy, resulting in a reduction in mitochondrial content. ATAD3A variation represents an additional link between mitochondrial dynamics and recognizable neurological syndromes, as seen with MFN2, OPA1, DNM1L, and STAT2 mutations.

}, keywords = {Adenosine Triphosphatases, Adult, Alleles, Animals, ATPases Associated with Diverse Cellular Activities, Axons, Cardiomyopathies, Child, Child, Preschool, Developmental Disabilities, DNA Copy Number Variations, Drosophila melanogaster, Female, Fibroblasts, Homozygote, Humans, Infant, Infant, Newborn, Male, Membrane Proteins, Mitochondria, Mitochondrial Proteins, Muscle Hypotonia, Muscles, Mutation, Nervous System Diseases, Neurons, Optic Atrophy, Phenotype, Polymorphism, Single Nucleotide, Syndrome, Young Adult}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.08.007}, author = {Harel, Tamar and Yoon, Wan Hee and Garone, Caterina and Gu, Shen and Coban-Akdemir, Zeynep and Eldomery, Mohammad K and Posey, Jennifer E and Jhangiani, Shalini N and Rosenfeld, Jill A and Cho, Megan T and Fox, Stephanie and Withers, Marjorie and Brooks, Stephanie M and Chiang, Theodore and Duraine, Lita and Erdin, Serkan and Yuan, Bo and Shao, Yunru and Moussallem, Elie and Lamperti, Costanza and Donati, Maria A and Smith, Joshua D and McLaughlin, Heather M and Eng, Christine M and Walkiewicz, Magdalena and Xia, Fan and Pippucci, Tommaso and Magini, Pamela and Seri, Marco and Zeviani, Massimo and Hirano, Michio and Hunter, Jill V and Srour, Myriam and Zanigni, Stefano and Lewis, Richard Alan and Muzny, Donna M and Lotze, Timothy E and Boerwinkle, Eric and Gibbs, Richard A and Hickey, Scott E and Graham, Brett H and Yang, Yaping and Buhas, Daniela and Martin, Donna M and Potocki, Lorraine and Graziano, Claudio and Bellen, Hugo J and Lupski, James R} }