Mutations in GPAA1, Encoding a GPI Transamidase Complex Protein, Cause Developmental Delay, Epilepsy, Cerebellar Atrophy, and Osteopenia.

Am J Hum Genet 2017 Nov;101(5):856-865

Centre Hospitalier Universitaire Sainte Justine Research Center, University of Montreal, Montreal, QC H3T1C5, Canada; Department of Pediatrics, University of Montreal, Montreal, QC H3T 1J4, Canada. Electronic address:

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.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajhg.2017.09.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673666PMC
November 2017
44 Reads
10.931 Impact Factor

Publication Analysis

Top Keywords

transamidase complex
12
gpi-anchored proteins
12
gpi anchor
8
developmental delay
8
atrophy osteopenia
8
splicing mutation
8
cerebellar atrophy
8
mutations gpaa1
8
development function
8
proteins
6
[pser51leu] c160_161delinsaa
4
c160_161delinsaa [pala54asn]
4
mutation c1164+5c>t
4
c152c>t [pser51leu]
4
mutations c152c>t
4
missense mutations
4
c1164+5c>t missense
4
c527g>c [ptrp176ser]
4
c1165g>c [pala389pro]
4
[pala389pro] individuals
4

Altmetric Statistics

Similar Publications