FIGURE 1.

Identification and in silico analysis of novel GLIS2 variant leading to nephronophthisis. (A) Pedigree diagram showing proband (arrowed) and known family consanguinity. (B) Kidney biopsy histology from proband showing dilated tubules and thickening and duplication of tubular basement membranes (hematoxylin and eosin, x40). (C) Sequence chromatograms demonstrating homozygous in-frame deletion in GLIS2 (NM 032575, c.562_576delCATGTCAACGATTAC; p.His188_Tyr192del) which was heterozygous in both parents. (D–G). In-frame deletion of GLIS2 is predicted to destroy the terminal motif sequence within the first zinc finger. (D) Protein model of human GLIS2 (green) bound to DNA (yellow and red) using structural homology to human GLI protein (PDB accession 2GLI). The predicted binding positions of Zn ions to each of the five zinc-finger (ZF) domains (labelled ZF1-5) are indicated by orange circles. (E) The predicted structure of GLIS2 ZF1 showing the classical ββα fold. The C₂H₂ residues Cys170, Cys175, His188, and His193 are labelled, and side chains are displayed. The five amino acid residues deleted in the His188_Tyr192 deletion are highlighted in magenta. (F) Zoomed in images from (D) of ZF1, showing the predicted wild-type structure (left) and predicted structure in the mutated protein (right). Left, the C₂H₂ residues are labelled and side chains creating the zinc binding pocket are shown. The region deleted in the mutated protein is highlighted in magenta. Right, His193 replaces His188 in the zinc binding pocket, however, the classical ZF motif is lost in the His199_Tyr192del variant. (G) Multiple sequence alignment of GLIS2. The C₂H₂ motifs of ZF1 and ZF2 are highlighted in green. The deleted sequence in the mutated protein is highlighted in magenta. *, completely conserved residue.