Fig. 3

In silico evaluation indicates MSH4 variants potentially influence protein function (A) A schematic diagram illustrating the exon-intron structure of the MSH4 gene, with the genomic locations of the c.2374 A > G (located in exon 18) and c.2222-2225delAAGA (located in exon 16) variants indicated. (B) A schematic representation of the MSH4 protein domains, including the locations of disease-associated genetic variants from Clinvar database and literature. Blue dots indicates missense disease-causing variants, and red dots represents loss of function disease-causing variants. (C) Multiple sequence alignments of MSH4 proteins from various species, demonstrating the high conservation of residues 741 (Lys) and 792 (Thr). (D) 3D structural prediction of MSH4 after site-directed mutagenesis using Pymol v2.6.0. At 792 position, three hydrogen bonds(H-bond) are observed with Ile 678 and Phe794 in wild type(Thr792), and two of them are abolished due to the replacement of Ala792. And p.Lys741Argfs*2 results in the loss of a substantial portion of the MutS_V domain