Fig. 2: Genomic analysis reveals compound heterozygous alleles in PAX7.

A Identification of PAX7 variants, c.335 C > T (exon 3) and c.1328 G > A (exon 8) through whole exome sequencing (WES) and confirmed by Sanger sequencing with chromatograms showing the variants alongside their corresponding nucleotide coding positions are presented. B Family pedigree showing PAX7 alleles (wild-type or variants) in proband family members. The affected individual (proband, filled symbol) carried both variants in PAX7 in compound heterozygosity. Individuals I:2, II:1,2,3 carried the heterozygous c.335 C > T variant only, while I:1 is heterozygous for the c.1328 G > A variant. C Schematic of PAX7 coding sequence with numbered exons, domains and positions of the c.335 C > T (exon 3) and c.1328 G > A variants. Amino acid changes are reported. Below, alignment of PAX7 paralog sequences across indicated species shows high conservation of Proline 112 and Cysteine 443. Pink letters highlight residue changes relative to human PAX7 sequence. D Ribbon representation of the human PAX7 protein AlphaFold model. The positions of the variants on the three-dimensional structure are highlighted. Cysteine 443 is located within the C-terminal region of PAX7 which is predicted to be unstructured. E Superimposition of the AlphaFold structure of conserved Paired domains and proximal regions of PAX7 and its orthologs PAX5 and PAX6 in complex with DNA (PDBID: 6pax, 1mdm). PAX7 is in green, PAX5 in purple, PAX6 in cyan and the DNA in magenta. The site of the P112L mutation is shown in red. Proline is conserved in PAX5,6,7 and in close vicinity of the protein loop binding to DNA.