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. 2017 Sep 22;8:130. doi: 10.3389/fgene.2017.00130

FIGURE 1.

FIGURE 1

Genetic analysis. (A) Pedigree of the Egyptian family reported herein. The index patient, II:1, is affected by 3-phosphoglycerate dehydrogenase deficiency, as indicated by homozygosity for a previously reported LoF mutation in PGHDH, p.Val425Met. In addition, she is homozygous for a nonsense mutation in IFIH1. (For brevity, the one-letter-code has been applied in the pedigree scheme.) (B) Electropherograms of the IFIH1 mutation [index patient, upper panel; heterozygous carrier (mother), lower panel]. (C) Scheme of IFIH1 gene and protein. The nonsense mutation (c.2665A>T/p.Lys889∗) resides in exon 14. If c.2665A>T was compatible with production of IFIH1 protein, it would lack the C-terminal domain (CTD), which is responsible for binding viral dsRNA. However, the lack of IFIH1 protein in patient fibroblasts (Figure 2) indicates that the homozygous nonsense mutation prevents IFIH1 protein production. Hel1, Hel2i, P, CTD. CARD, caspase activation recruitment domain; Hel, helicase domain; Hel1 and Hel2, the two conserved core Hel domains; Hel2i, insertion domain that is conserved in the RIG-I-like family; P, pincer/bridge region connecting Hel2 to the CTD.