(a) Identification of a heterozygous c.2787+1G>T in the splicing donor site in intron 21 and a heterozygous c.3774_3775insC in exon 27 of the ABCC6 gene in the patients’ DNA. The patients’ parents are heterozygous carriers (arrows). (b) Bioinformatics analysis of the ABCC6 mutations. Four independent programs, MutationTaster, Human Splicing Finder, SIFT, and CADD (the Combined Annotation Depletion score) were used to predict the consequences of the mutations. The allele frequency of c.2787+1G>T and c.3774_3775insC is exceedingly rare in over 130,000 healthy individuals in the Genome Aggregation Database (gnomAD), and thus, both variants are unlikely to be polymorphisms.