@article {494, title = {A homozygous founder mutation in associates with a neurodevelopmental disorder characterised by microcephaly, epilepsy and autistic features.}, journal = {J Med Genet}, volume = {55}, year = {2018}, month = {2018 01}, pages = {48-54}, abstract = {

BACKGROUND: Transport protein particle (TRAPP) is a multisubunit complex that regulates membrane trafficking through the Golgi apparatus. The clinical phenotype associated with mutations in various TRAPP subunits has allowed elucidation of their functions in specific tissues. The role of some subunits in human disease, however, has not been fully established, and their functions remain uncertain.

OBJECTIVE: We aimed to expand the range of neurodevelopmental disorders associated with mutations in TRAPP subunits by exome sequencing of consanguineous families.

METHODS: Linkage and homozygosity mapping and candidate gene analysis were used to identify homozygous mutations in families. Patient fibroblasts were used to study splicing defect and zebrafish to model the disease.

RESULTS: We identified six individuals from three unrelated families with a founder homozygous splice mutation in , encoding a core subunit of the complex TRAPP I. Patients manifested a neurodevelopmental disorder characterised by microcephaly, epilepsy and autistic features, and showed splicing defect. Zebrafish morphants replicated the human phenotype, displaying decreased head size and neuronal hyperexcitability, leading to a lower seizure threshold.

CONCLUSION: This study provides clinical and functional evidence of the role of in brain development and function.

}, keywords = {Animals, Autistic Disorder, Epilepsy, Founder Effect, Genetic Association Studies, Homozygote, Humans, Microcephaly, Mutation, Neurodevelopmental Disorders, Phenotype, Vesicular Transport Proteins, Zebrafish}, issn = {1468-6244}, doi = {10.1136/jmedgenet-2017-104627}, author = {Marin-Valencia, Isaac and Novarino, Gaia and Johansen, Anide and Rosti, Basak and Issa, Mahmoud Y and Musaev, Damir and Bhat, Gifty and Scott, Eric and Silhavy, Jennifer L and Stanley, Valentina and Rosti, Rasim O and Gleeson, Jeremy W and Imam, Farhad B and Zaki, Maha S and Gleeson, Joseph G} } @article {351, title = {Biallelic mutations in the 3{\textquoteright} exonuclease TOE1 cause pontocerebellar hypoplasia and uncover a role in snRNA processing.}, journal = {Nat Genet}, volume = {49}, year = {2017}, month = {2017 Mar}, pages = {457-464}, abstract = {

Deadenylases are best known for degrading the poly(A) tail during mRNA decay. The deadenylase family has expanded throughout evolution and, in mammals, consists of 12 Mg-dependent 3{\textquoteright}-end RNases with substrate specificity that is mostly unknown. Pontocerebellar hypoplasia type 7 (PCH7) is a unique recessive syndrome characterized by neurodegeneration and ambiguous genitalia. We studied 12 human families with PCH7, uncovering biallelic, loss-of-function mutations in TOE1, which encodes an unconventional deadenylase. toe1-morphant zebrafish displayed midbrain and hindbrain degeneration, modeling PCH-like structural defects in vivo. Surprisingly, we found that TOE1 associated with small nuclear RNAs (snRNAs) incompletely processed spliceosomal. These pre-snRNAs contained 3{\textquoteright} genome-encoded tails often followed by post-transcriptionally added adenosines. Human cells with reduced levels of TOE1 accumulated 3{\textquoteright}-end-extended pre-snRNAs, and the immunoisolated TOE1 complex was sufficient for 3{\textquoteright}-end maturation of snRNAs. Our findings identify the cause of a neurodegenerative syndrome linked to snRNA maturation and uncover a key factor involved in the processing of snRNA 3{\textquoteright} ends.

}, keywords = {Alleles, Animals, Cerebellar Diseases, Exonucleases, Female, Humans, Male, Mice, Mutation, Neurodegenerative Diseases, Nuclear Proteins, RNA, Messenger, RNA, Small Nuclear, Spliceosomes, Zebrafish}, issn = {1546-1718}, doi = {10.1038/ng.3762}, author = {Lardelli, Rea M and Schaffer, Ashleigh E and Eggens, Veerle R C and Zaki, Maha S and Grainger, Stephanie and Sathe, Shashank and Van Nostrand, Eric L and Schlachetzki, Zinayida and Rosti, Basak and Akizu, Naiara and Scott, Eric and Silhavy, Jennifer L and Heckman, Laura Dean and Rosti, Rasim Ozgur and Dikoglu, Esra and Gregor, Anne and Guemez-Gamboa, Alicia and Musaev, Damir and Mande, Rohit and Widjaja, Ari and Shaw, Tim L and Markmiller, Sebastian and Marin-Valencia, Isaac and Davies, Justin H and de Meirleir, Linda and Kayserili, H{\"u}lya and Altunoglu, Umut and Freckmann, Mary Louise and Warwick, Linda and Chitayat, David and Blaser, Susan and {\c C}a{\u g}layan, Ahmet Okay and Bilguvar, Kaya and Per, H{\"u}seyin and Fagerberg, Christina and Christesen, Henrik T and Kibaek, Maria and Aldinger, Kimberly A and Manchester, David and Matsumoto, Naomichi and Muramatsu, Kazuhiro and Saitsu, Hirotomo and Shiina, Masaaki and Ogata, Kazuhiro and Foulds, Nicola and Dobyns, William B and Chi, Neil C and Traver, David and Spaccini, Luigina and Bova, Stefania Maria and Gabriel, Stacey B and G{\"u}nel, Murat and Valente, Enza Maria and Nassogne, Marie-Cecile and Bennett, Eric J and Yeo, Gene W and Baas, Frank and Lykke-Andersen, Jens and Gleeson, Joseph G} } @article {382, title = {Homozygous Mutations in TBC1D23 Lead to a Non-degenerative Form of Pontocerebellar Hypoplasia.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Sep 07}, pages = {441-450}, abstract = {

Pontocerebellar hypoplasia (PCH) represents a group of recessive developmental disorders characterized by impaired growth of the pons and cerebellum, which frequently follows a degenerative course. Currently, there are 10 partially overlapping clinical subtypes and 13 genes known mutated in PCH. Here, we report biallelic TBC1D23 mutations in six individuals from four unrelated families manifesting a non-degenerative form of PCH. In addition to reduced volume of pons and cerebellum, affected individuals had microcephaly, psychomotor delay, and ataxia. In zebrafish, tbc1d23 morphants replicated the human phenotype showing hindbrain volume loss. TBC1D23 localized at the trans-Golgi and was regulated by the small GTPases Arl1 and Arl8, suggesting a role in trans-Golgi membrane trafficking. Altogether, this study provides a causative link between TBC1D23 mutations and PCH and suggests a less severe clinical course than other PCH subtypes.

}, keywords = {Adolescent, Animals, Cerebellar Diseases, Child, Child, Preschool, Female, GTPase-Activating Proteins, HeLa Cells, Homozygote, Humans, Male, Microcephaly, Mutation, Pedigree, Phenotype, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.07.015}, author = {Marin-Valencia, Isaac and Gerondopoulos, Andreas and Zaki, Maha S and Ben-Omran, Tawfeg and Almureikhi, Mariam and Demir, Ercan and Guemez-Gamboa, Alicia and Gregor, Anne and Issa, Mahmoud Y and Appelhof, Bart and Roosing, Susanne and Musaev, Damir and Rosti, Basak and Wirth, Sara and Stanley, Valentina and Baas, Frank and Barr, Francis A and Gleeson, Joseph G} } @article {63, title = {PYCR2 Mutations cause a lethal syndrome of microcephaly and failure to thrive.}, journal = {Ann Neurol}, volume = {80}, year = {2016}, month = {2016 07}, pages = {59-70}, abstract = {

OBJECTIVE: A study was undertaken to characterize the clinical features of the newly described hypomyelinating leukodystrophy type 10 with microcephaly. This is an autosomal recessive disorder mapped to chromosome 1q42.12 due to mutations in the PYCR2 gene, encoding an enzyme involved in proline synthesis in mitochondria.

METHODS: From several international clinics, 11 consanguineous families were identified with PYCR2 mutations by whole exome or targeted sequencing, with detailed clinical and radiological phenotyping. Selective mutations from patients were tested for effect on protein function.

RESULTS: The characteristic clinical presentation of patients with PYCR2 mutations included failure to thrive, microcephaly, craniofacial dysmorphism, progressive psychomotor disability, hyperkinetic movements, and axial hypotonia with variable appendicular spasticity. Patients did not survive beyond the first decade of life. Brain magnetic resonance imaging showed global brain atrophy and white matter T2 hyperintensities. Routine serum metabolic profiles were unremarkable. Both nonsense and missense mutations were identified, which impaired protein multimerization.

INTERPRETATION: PYCR2-related syndrome represents a clinically recognizable condition in which PYCR2 mutations lead to protein dysfunction, not detectable on routine biochemical assessments. Mutations predict a poor outcome, probably as a result of impaired mitochondrial function. Ann Neurol 2016;80:59-70.

}, keywords = {Adolescent, Child, Child, Preschool, Codon, Nonsense, Exome, Failure to Thrive, Female, Fibroblasts, Gene Expression, Genetic Predisposition to Disease, Genotype, Humans, Infant, Male, Microcephaly, Mutation, Missense, Phenotype, Primary Cell Culture, Pyrroline Carboxylate Reductases, Syndrome, Transfection, Young Adult}, issn = {1531-8249}, doi = {10.1002/ana.24678}, author = {Zaki, Maha S and Bhat, Gifty and Sultan, Tipu and Issa, Mahmoud and Jung, Hea-Jin and Dikoglu, Esra and Selim, Laila and G Mahmoud, Imam and Abdel-Hamid, Mohamed S and Abdel-Salam, Ghada and Marin-Valencia, Isaac and Gleeson, Joseph G} }