@article {493, title = {Mutations in GPAA1, Encoding a GPI Transamidase Complex Protein, Cause Developmental Delay, Epilepsy, Cerebellar Atrophy, and Osteopenia.}, journal = {Am J Hum Genet}, volume = {101}, year = {2017}, month = {2017 Nov 02}, pages = {856-865}, abstract = {

Approximately one in every 200 mammalian proteins is anchored to the cell membrane through a glycosylphosphatidylinositol (GPI) anchor. These proteins play important roles notably in neurological development and function. To date, more than 20 genes have been implicated in the biogenesis of GPI-anchored proteins. GPAA1 (glycosylphosphatidylinositol anchor attachment 1) is an essential component of the transamidase complex along with PIGK, PIGS, PIGT, and PIGU (phosphatidylinositol-glycan biosynthesis classes K, S, T, and U, respectively). This complex orchestrates the attachment of the GPI anchor to the C terminus of precursor proteins in the endoplasmic reticulum. Here, we report bi-allelic mutations in GPAA1 in ten individuals from five families. Using whole-exome sequencing, we identified two frameshift mutations (c.981_993del [p.Gln327Hisfs102] and c.920delG [p.Gly307Alafs11]), one intronic splicing mutation (c.1164+5C>T), and six missense mutations (c.152C>T [p.Ser51Leu], c.160_161delinsAA [p.Ala54Asn], c.527G>C [p.Trp176Ser], c.869T>C [p.Leu290Pro], c.872T>C [p.Leu291Pro], and c.1165G>C [p.Ala389Pro]). Most individuals presented with global developmental delay, hypotonia, early-onset seizures, cerebellar atrophy, and osteopenia. The splicing mutation was found to decrease GPAA1 mRNA. Moreover, flow-cytometry analysis of five available individual samples showed that several GPI-anchored proteins had decreased cell-surface abundance in leukocytes (FLAER, CD16, and CD59) or fibroblasts (CD73 and CD109). Transduction of fibroblasts with a lentivirus encoding the wild-type protein partially rescued the deficiency of GPI-anchored proteins. These findings highlight the role of the transamidase complex in the development and function of the cerebellum and the skeletal system.

}, keywords = {Acyltransferases, Adolescent, Adult, Alleles, Atrophy, Bone Diseases, Metabolic, Cerebellum, Child, Child, Preschool, Developmental Disabilities, Epilepsy, Exome, Female, Fibroblasts, Glycosylphosphatidylinositols, Humans, Male, Membrane Glycoproteins, Muscle Hypotonia, Mutation, Pedigree, RNA, Messenger, Seizures}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.09.020}, author = {Nguyen, Thi Tuyet Mai and Murakami, Yoshiko and Sheridan, Eamonn and Ehresmann, Sophie and Rousseau, Justine and St-Denis, Anik and Chai, Guoliang and Ajeawung, Norbert F and Fairbrother, Laura and Reimschisel, Tyler and Bateman, Alexandra and Berry-Kravis, Elizabeth and Xia, Fan and Tardif, Jessica and Parry, David A and Logan, Clare V and Diggle, Christine and Bennett, Christopher P and Hattingh, Louise and Rosenfeld, Jill A and Perry, Michael Scott and Parker, Michael J and Le Deist, Fran{\c c}oise and Zaki, Maha S and Ignatius, Erika and Isohanni, Pirjo and L{\"o}nnqvist, Tuula and Carroll, Christopher J and Johnson, Colin A and Gleeson, Joseph G and Kinoshita, Taroh and Campeau, Philippe M} } @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} } @article {205, title = {Biallelic truncating mutations in FMN2, encoding the actin-regulatory protein Formin 2, cause nonsyndromic autosomal-recessive intellectual disability.}, journal = {Am J Hum Genet}, volume = {95}, year = {2014}, month = {2014 Dec 04}, pages = {721-8}, abstract = {

Dendritic spines represent the major site of neuronal activity in the brain; they serve as the receiving point for neurotransmitters and undergo rapid activity-dependent morphological changes that correlate with learning and memory. Using a combination of homozygosity mapping and next-generation sequencing in two consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability, we identified truncating mutations in formin 2 (FMN2), encoding a protein that belongs to the formin family of actin cytoskeleton nucleation factors and is highly expressed in the maturing brain. We found that FMN2 localizes to punctae along dendrites and that germline inactivation of mouse Fmn2 resulted in animals with decreased spine density; such mice were previously demonstrated to have a conditioned fear-learning defect. Furthermore, patient neural cells derived from induced pluripotent stem cells showed correlated decreased synaptic density. Thus, FMN2 mutations link intellectual disability either directly or indirectly to the regulation of actin-mediated synaptic spine density.

}, keywords = {Adolescent, Adult, Base Sequence, Chromosome Disorders, Cohort Studies, Consanguinity, Egypt, Exome, Female, Genes, Recessive, Genetic Linkage, High-Throughput Nucleotide Sequencing, Homozygote, Humans, Intellectual Disability, Male, Microfilament Proteins, Molecular Sequence Data, Nuclear Proteins, Pakistan, Pedigree, Sequence Analysis, DNA, Sequence Deletion}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.10.016}, author = {Law, Rosalind and Dixon-Salazar, Tracy and Jerber, Julie and Cai, Na and Abbasi, Ansar A and Zaki, Maha S and Mittal, Kirti and Gabriel, Stacey B and Rafiq, Muhammad Arshad and Khan, Valeed and Nguyen, Maria and Ali, Ghazanfar and Copeland, Brett and Scott, Eric and Vasli, Nasim and Mikhailov, Anna and Khan, Muhammad Nasim and Andrade, Danielle M and Ayaz, Muhammad and Ansar, Muhammad and Ayub, Muhammad and Vincent, John B and Gleeson, Joseph G} } @article {268, title = {Exome sequencing links corticospinal motor neuron disease to common neurodegenerative disorders.}, journal = {Science}, volume = {343}, year = {2014}, month = {2014 Jan 31}, pages = {506-511}, abstract = {

Hereditary spastic paraplegias (HSPs) are neurodegenerative motor neuron diseases characterized by progressive age-dependent loss of corticospinal motor tract function. Although the genetic basis is partly understood, only a fraction of cases can receive a genetic diagnosis, and a global view of HSP is lacking. By using whole-exome sequencing in combination with network analysis, we identified 18 previously unknown putative HSP genes and validated nearly all of these genes functionally or genetically. The pathways highlighted by these mutations link HSP to cellular transport, nucleotide metabolism, and synapse and axon development. Network analysis revealed a host of further candidate genes, of which three were mutated in our cohort. Our analysis links HSP to other neurodegenerative disorders and can facilitate gene discovery and mechanistic understanding of disease.

}, keywords = {Animals, Axons, Biological Transport, Cohort Studies, Exome, Gene Regulatory Networks, Genetic Association Studies, Humans, Motor Neuron Disease, Mutation, Neurons, Nucleotides, Pyramidal Tracts, Sequence Analysis, DNA, Spastic Paraplegia, Hereditary, Synapses, Transcriptome, Zebrafish}, issn = {1095-9203}, doi = {10.1126/science.1247363}, author = {Novarino, Gaia and Fenstermaker, Ali G and Zaki, Maha S and Hofree, Matan and Silhavy, Jennifer L and Heiberg, Andrew D and Abdellateef, Mostafa and Rosti, Basak and Scott, Eric and Mansour, Lobna and Masri, Amira and Kayserili, H{\"u}lya and Al-Aama, Jumana Y and Abdel-Salam, Ghada M H and Karminejad, Ariana and Kara, Majdi and Kara, Bulent and Bozorgmehri, Bita and Ben-Omran, Tawfeg and Mojahedi, Faezeh and El Din Mahmoud, Iman Gamal and Bouslam, Naima and Bouhouche, Ahmed and Benomar, Ali and Hanein, Sylvain and Raymond, Laure and Forlani, Sylvie and Mascaro, Massimo and Selim, Laila and Shehata, Nabil and Al-Allawi, Nasir and Bindu, P S and Azam, Matloob and G{\"u}nel, Murat and Caglayan, Ahmet and Bilguvar, Kaya and Tolun, Aslihan and Issa, Mahmoud Y and Schroth, Jana and Spencer, Emily G and Rosti, Rasim O and Akizu, Naiara and Vaux, Keith K and Johansen, Anide and Koh, Alice A and Megahed, Hisham and Durr, Alexandra and Brice, Alexis and Stevanin, Giovanni and Gabriel, Stacy B and Ideker, Trey and Gleeson, Joseph G} }