@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 {97, title = {POGZ truncating alleles cause syndromic intellectual disability.}, journal = {Genome Med}, volume = {8}, year = {2016}, month = {2016 Jan 06}, pages = {3}, abstract = {

BACKGROUND: Large-scale cohort-based whole exome sequencing of individuals with neurodevelopmental disorders (NDDs) has identified numerous novel candidate disease genes; however, detailed phenotypic information is often lacking in such studies. De novo mutations in pogo transposable element with zinc finger domain (POGZ) have been identified in six independent and diverse cohorts of individuals with NDDs ranging from autism spectrum disorder to developmental delay.

METHODS: Whole exome sequencing was performed on five unrelated individuals. Sanger sequencing was used to validate variants and segregate mutations with the phenotype in available family members.

RESULTS: We identified heterozygous truncating mutations in POGZ in five unrelated individuals, which were confirmed to be de novo or not present in available parental samples. Careful review of the phenotypes revealed shared features that included developmental delay, intellectual disability, hypotonia, behavioral abnormalities, and similar facial characteristics. Variable features included short stature, microcephaly, strabismus and hearing loss.

CONCLUSIONS: While POGZ has been associated with neurodevelopmental disorders in large cohort studies, our data suggest that loss of function variants in POGZ lead to an identifiable syndrome of NDD with specific phenotypic traits. This study exemplifies the era of human reverse clinical genomics ushered in by large disease-directed cohort studies; first defining a new syndrome molecularly and, only subsequently, phenotypically.

}, keywords = {Adolescent, Adult, Alleles, Child, Preschool, Exome, Female, Heterozygote, Humans, Infant, Intellectual Disability, Male, Mutation, Sequence Analysis, DNA, Transposases}, issn = {1756-994X}, doi = {10.1186/s13073-015-0253-0}, author = {White, Janson and Beck, Christine R and Harel, Tamar and Posey, Jennifer E and Jhangiani, Shalini N and Tang, Sha and Farwell, Kelly D and Powis, Z{\"o}e and Mendelsohn, Nancy J and Baker, Janice A and Pollack, Lynda and Mason, Kati J and Wierenga, Klaas J and Arrington, Daniel K and Hall, Melissa and Psychogios, Apostolos and Fairbrother, Laura and Walkiewicz, Magdalena and Person, Richard E and Niu, Zhiyv and Zhang, Jing and Rosenfeld, Jill A and Muzny, Donna M and Eng, Christine and Beaudet, Arthur L and Lupski, James R and Boerwinkle, Eric and Gibbs, Richard A and Yang, Yaping and Xia, Fan and Sutton, V Reid} }