A Novel α-Galactosidase A Splicing Mutation Predisposes to Fabry Disease.

Ping Li,Qiuhong Xiong,Na Zhao,Yong-An Zhou,Lijuan Zhang,Han Xiao,Changxin Wu

doi:10.3389/fgene.2019.00060

Ping Li, Qiuhong Xiong + Show 5 more

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https://doi.org/10.3389/fgene.2019.00060

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Abstract

Fabry disease (FD) is a rare X-linked α-galactosidase A (GLA) deficiency, resulting in progressive lysosomal accumulation of globotriaosylceramide (Gb3) in a variety of cell types. Here, we report a novel splicing mutation (c.801 + 1G > A) that results in alternative splicing in GLA of a FD patient with variable phenotypic presentations of renal involvement. Sequencing of the RT-PCR products from the patient’s blood sample reveals a 36-nucleotide (nt) insertion exists at the junction between exons 5 and 6 of the GLA cDNA. Splicing assay indicates that the mutated minigene produces an alternatively spliced transcript which causes a frameshift resulting in an early termination of protein expression. Immunofluorescence shows puncta in cytoplasm for mutated GLA whereas uniform staining small dots evenly distributed inside cytoplasm for wild type GLA in transfected HeLa cells. The increased senescence and decreased GLA enzyme activity suggest that the abnormalities might be due to the altered localization which further might result from the lack of the C-terminal end of GLA. Our study reveals the pathogenesis of splicing mutation c.801 + 1G > A to FD and provides scientific foundation for accurate diagnosis and precise medical intervention for FD.

Highlights

We identified a novel splicing mutation in a Fabry disease (FD) patient in which the first nucleotide of galactosidase A (GLA) intron 5 is changed from G to A
All patients included in this study with clinical manifestations of FD were recruited from four unrelated Chinese families
The blood samples were obtained and Sanger sequencing of genomic DNA isolated from the samples were performed for GLA gene

Summary

Introduction

Fabry disease (OMIM #301500, FD) is a rare X-linked recessive hereditary systemic disorder of glycosphingolipid metabolism, caused by total or partial decreased activity of alpha-galactosidase A (a-Gal or GLA, EC 3.2.1.22; UniProt P06280) (Brady et al, 1967; Kint, 1970) and results in lysosomal accumulations of globotriaosylceramide (Gb3), and other neutral glycosphingolipids in various cells and tissues including skin, eye, kidney, heart, brain, and peripheral nervous system (Zarate and Hopkin, 2008).Classical FD is a complex multisystemic disorder with prominent features like neuropathic pain, exercise intolerance, gastrointestinal abnormalities, hyperhidrosis, corneal changes, angiokeratomas, progressive renal and cardiac deterioration, and a reduced life expectancy (Zarate and Hopkin, 2008). Fabry disease (OMIM #301500, FD) is a rare X-linked recessive hereditary systemic disorder of glycosphingolipid metabolism, caused by total or partial decreased activity of alpha-galactosidase A (a-Gal or GLA, EC 3.2.1.22; UniProt P06280) (Brady et al, 1967; Kint, 1970) and results in lysosomal accumulations of globotriaosylceramide (Gb3), and other neutral glycosphingolipids in various cells and tissues including skin, eye, kidney, heart, brain, and peripheral nervous system (Zarate and Hopkin, 2008). The disease may present in milder forms involving primarily the heart or the kidneys (von Scheidt et al, 1991; Nakao et al, 2003). The milder forms of the disease have a later onset and are usually associated with some residual levels of GLA enzyme activities. The ubiquitously expressed GLA gene (located at position Xq22.1, OMIM 300644, RefSeq X14448, HGNC 4296; NCBI reference sequence NM_000169.2) contains 7 exons encoding the 429 amino acid GLA polypeptide, including an N-terminal 31-residue signal peptide.

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