Functional and pharmacological evaluation of novel GLA variants in Fabry disease identifies six (two de novo) causative mutations and two amenable variants to the chaperone DGJ.

Abstract

BACKGROUND:

Allelic heterogeneity is an important feature of the GLA gene for which almost 900 known genetic variants have been discovered so far. Pathogenetic GLA variants cause alpha-galactosidase A (α-Gal A) enzyme deficiency leading to the X-linked lysosomal storage disorder Fabry disease (FD). Benign GLA intronic and exonic variants (e.g. pseudodeficient p.Asp313Tyr) have also been described. Some GLA missense variants, previously deemed to be pathogenetic (e.g. p.Glu66Gln and p.Arg118Cys), they have been reclassified as benign after re-evaluation by functional and population studies. Hence, the functional role of novel GLA variants should be investigated to assess their clinical relevance.

RESULTS:

We identified six GLA variants in 4 males and 2 females who exhibited symptoms of FD: c.159C>G p.(Asn53Lys), c.400T>C p.(Tyr134His), c.680G>C (p.Arg227Pro), c.815A>T p.(Asn272Ile), c.907A>T p.(Ile303Phe) and c.1163_1165delTCC (p.Leu388del). We evaluated their impact on the α-Gal A protein by bioinformatic analysis and homology modelling, by analysis of the GLA mRNA, and by site-directed mutagenesis and in vitro expression studies. We also measured their responsiveness to the pharmacological chaperone DGJ.

CONCLUSIONS:

The six detected GLA variants cause deficient α-Gal A activity and impairment or loss of the protein wild-type structure. We found p.Asn53Lys and p.Ile303Phe variants to be susceptible to DGJ.

• Authors: Lorenzo Ferri, Duccio Malesci, Antonella Fioravanti, Gaia Bagordo, Armando Filippini, Anna Ficcadenti, Raffaele Manna, Daniela Antuzzi, Elena Verrecchia, Ilaria Donati, Renzo Mignani, Catia Cavicchi, Renzo Guerrini, Amelia Morrone
• Journal: Clinica chimica acta; international journal of clinical chemistry (Clin Chim Acta) Vol. 481 Pg. 25-33 (Jun 2018) ISSN: 1873-3492 [Electronic] Netherlands
• PMID: 29476735 (Publication Type: Journal Article)
• Copyright: Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Chemical References

• Molecular Chaperones
• RNA, Messenger
• GLA protein, human
• alpha-Galactosidase

Topics

• Adolescent
• Adult
• Aged
• Computational Biology
• Fabry Disease (drug therapy, genetics, pathology)
• Female
• Genetic Variation (drug effects, genetics)
• Humans
• Male
• Middle Aged
• Molecular Chaperones (pharmacology)
• Mutation
• RNA, Messenger (genetics)
• alpha-Galactosidase (genetics, metabolism)