Identification of Abcc6
as the major causal gene for dystrophic cardiac calcification in mice through integrative genomics.
Among the 18 families, ABCC6 variants were identified in compound heterozygous or homozygous states in 13 probands and in heterozygous states in four probands, while no variants were identified in one proband (Table 1).
In the current study, we identified eight disease-causing variants (p.Q378X, p.R419Q, p.V848CfsX83, p.R1114C, p.R1357W, p.N428S, p.H647Y, and p.S1125F) in the ABCC6 gene, two of which (p.H647Y and p.S1125F) were novel variants.
Only one large-scale ABCC6 gene analysis study has been previously reported; it was performed in 54 Japanese patients with AS, and six pathogenic variants (p.R419Q, p.E422K, p.V848CfsX83, a deletion of exon 23, c.3774_3775insC, and p.E1427K) were found .
The combined effects on age of disease onset of activity-affecting variants of genes encoding antioxidant enzymes and ABCC6 mutations likely to cause complete loss of MRP6-transport activity also suggest the involvement of MRP6 in the regulation of oxidative stress; however, these arguments will continue to be speculative as long as the physiological substrate of MRP6 remains unidentified.
The strong expression of ABCC6 in liver and kidney, organs not primarily affected by PXE, lead to the assumption that PXE is a systemic disease (38).
ABCC6 mutations in Italian families affected by pseudoxanthoma elasticum (PXE).
Characteristic for PXE is a great variability in the clinical course and phenotype of PXE, even among patients with the same or functionally similar ABCC6 mutations.
Recent studies have described strong SPP1 expression due to the Dyscalc1 locus in mice suffering from dystrophic cardiac calcification, with abcc6 gene as a potential candidate gene (20, 21).
Mutational analysis of the ABCC6 gene and the proximal ABCC6 gene promoter in German patients with pseudoxanthoma elasticum (PXE) [Mutations in Brief].
Mutational analysis of the ABCC6 gene and the common c.3421C>T mutation were performed as described previously (13, 15, 16).
The 16-kb deletion spanning exons 23 to 29 of the ABCC6 gene was identified in the heterozygous state in 9 PXE patients.