Update of the pompe disease mutation database with 60 novel GAA sequence variants and additional studies on the functional effect of 34 previously reported variants
Kroos, Marian × Hoogeveen-Westerveld, Marianne Michelakakis, Helen Pomponio, Robert Van der Ploeg, Ans Halley, Dicky Reuser, Arnold Robberecht, Wim GAA Database Consortium #
John Wiley & Sons, Inc.
Human Mutation vol:33 issue:8 pages:1161-1165
Pompe disease is an autosomal recessive lysosomal glycogen storage disorder, characterized by progressive muscle weakness. Deficiency of acid α-glucosidase (EC; 22.214.171.124/3) can be caused by numerous pathogenic variants in the GAA gene. The Pompe Disease Mutation Database at http://www.pompecenter.nl aims to list all variants and their effect. This update reports on 94 variants. We examined 35 novel and 34 known mutations by site-directed mutagenesis and transient expression in COS-7 cells or HEK293T cells. Each of these mutations was given a severity rating using a previously published system, based on the level of acid α-glucosidase activity in medium and transfected cells and on the quantity and quality of the different molecular mass species in the posttranslational modification and transport of acid α-glucosidase. This approach enabled to classify 55 missense mutations as pathogenic and 13 as likely nonpathogenic. Based on their nature and the use of in silico analysis (Alamut® software), 12 of the additional 25 novel mutations were predicted to be pathogenic including 4 splicing mutations, 6 mutations leading to frameshift, and 2 point mutations causing stop codons. Seven of the additional mutations were considered nonpathogenic (4 silent and 3 occurring in intron regions), and 6 are still under investigation.