Dataset Information

ATP7B variant c.1934T?>?G p.Met645Arg causes Wilson disease by promoting exon 6 skipping.

ABSTRACT: Wilson disease is a recessive genetic disorder caused by pathogenic loss-of-function variants in the ATP7B gene. It is characterized by disrupted copper homeostasis resulting in liver disease and/or neurological abnormalities. The variant NM_000053.3:c.1934T?>?G (Met645Arg) has been reported as compound heterozygous, and is highly prevalent among Wilson disease patients of Spanish descent. Accordingly, it is classified as pathogenic by leading molecular diagnostic centers. However, functional studies suggest that the amino acid change does not alter protein function, leading one ClinVar submitter to question its pathogenicity. Here, we used a minigene system and gene-edited HepG2 cells to demonstrate that c.1934T?>?G causes ~70% skipping of exon 6. Exon 6 skipping results in frameshift and stop-gain, leading to loss of ATP7B function. The elucidation of the mechanistic effect for this variant resolves any doubt about its pathogenicity and enables the development of genetic medicines for restoring correct splicing.

SUBMITTER: Merico D

PROVIDER: S-EPMC7142117 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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<i>ATP7B</i> variant c.1934T > G p.Met645Arg causes Wilson disease by promoting exon 6 skipping.

Merico Daniele D Spickett Carl C O'Hara Matthew M Kakaradov Boyko B Deshwar Amit G AG Fradkin Phil P Gandhi Shreshth S Gao Jiexin J Grant Solomon S Kron Ken K Schmitges Frank W FW Shalev Zvi Z Sun Mark M Verby Marta M Cahill Matthew M Dowling James J JJ Fransson Johan J Wienholds Erno E Frey Brendan J BJ

NPJ genomic medicine 20200408

Wilson disease is a recessive genetic disorder caused by pathogenic loss-of-function variants in the <i>ATP7B</i> gene. It is characterized by disrupted copper homeostasis resulting in liver disease and/or neurological abnormalities. The variant NM_000053.3:c.1934T > G (Met645Arg) has been reported as compound heterozygous, and is highly prevalent among Wilson disease patients of Spanish descent. Accordingly, it is classified as pathogenic by leading molecular diagnostic centers. However, functi ...[more]

PMID: 32284880

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Project description:Schizophrenia is a heterogeneous psychiatric disorder characterized by positive symptoms such as hallucinations and delusions, negative symptoms such as anhedonia and flat affect, and cognitive impairment. Recently, glucuronate (GlucA) levels were reported to be significantly higher in serum of patients with schizophrenia than those in healthy controls. The accumulation of GlucA is known to be related to treatment-resistant schizophrenia, since GlucA is known to promote drug excretion by forming conjugates with drugs. However, the cause of GlucA accumulation remains unclear. Aldo-keto reductase family one member A1 (AKR1A1) is an oxidoreductase that catalyzes the reduction of GlucA. Genetic loss of AKR1A1 function is known to result in the accumulation of GlucA in rodents. Here, we aimed to explore genetic defects in AKR1A1 in patients with schizophrenia, which may result in the accumulation of GlucA. We identified 28 variants of AKR1A1 in patients with schizophrenia and control subjects. In particular, we identified a silent c.753G > A (rs745484618, p. Arg251Arg) variant located at the first position of exon 8 to be associated with schizophrenia. Using a minigene assay, we found that the c.753G > A variant induced exon 8 skipping in AKR1A1, resulting in a frameshift mutation, which in turn led to truncation of the AKR1A1 protein. Using the recombinant protein, we demonstrated that the truncated AKR1A1 completely lost its activity. Furthermore, we showed that AKR1A1 mRNA expression in the whole blood cells of individuals with the c.753G > A variant tended to be lower than that in those without the variants, leading to lower AKR activity. Our findings suggest that AKR1A1 carrying the c.753G > A variant induces exon skipping, leading to a loss of gene expression and enzymatic activity. Thus, GlucA patients with schizophrenia with the c.753G > A variant may show higher GlucA levels, leading to drug-resistant schizophrenia, since drug excretion by GlucA is enhanced.

Dataset Information

ATP7B variant c.1934T?>?G p.Met645Arg causes Wilson disease by promoting exon 6 skipping.

Publications

<i>ATP7B</i> variant c.1934T > G p.Met645Arg causes Wilson disease by promoting exon 6 skipping.

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