Table 1.
DNA screening by next-generation sequencing.
Fig 1.
The paired domain of PAX family proteins (DNA binding domain) is well conserved among PAX family members (A). Panel B shows a partial amino acid sequence of the paired domain of PAX family proteins and PAX2 from different species. Yellow bars indicate sequences with 100% identity with human PAX1–9 and four different species. Red and blue bars indicate mutations identified in the present study and previous studies, respectively. Five mutation of PAX2 were detected in exon 2. Three out of five mutations were insertion or deletion mutation in exon 2 with frameshifts. These frameshifts created new stop codons and thus generate nonsense mutations. Two other mutations were single nucleotide mutations (ex2 c.187G>A, G63S and ex2 c.212G>C, R71T). These two mutations are shown in panels C. The 3D-structure of the paired domain is shown in panel Ci. The 3D-structure highlighted by the square in panel Ci is magnified in panel Cii. Changes in structure and electric polarity by G63S and R71T mutations are shown in panels Ciii to vi. Wild-type amino acids involved in DNA binding, glycine and arginine are shown in red. These two non-polar amino acid residues were mutated to the polar amino acid residues, serine and threonine, respectively. Blue and red highlighted amino acids in panels Cv and vi are hydrophobic and hydrophilic, respectively.
Table 2.
Gene mutation in renal coloboma syndrome.
Fig 2.
Clinical manifestation of kidney in patients with PAX2 mutations.
PAX2 mutations substantially contribute to the renal manifestations of RCS. In patients without dialysis or kidney transplantation, estimated GFR were lower in patients with PAX2 mutations (A), and proteinuria was more severe in patients with PAX2 mutations (B). Histology of a renal biopsy specimen from Patient 8 is shown in panel C.A representative segmental sclerosing lesion is observed at a glomerulus by PAS (i, ii) and PAM (iii) staining. Original magnifications; panel I, ×100; planes ii and iii, ×400. Panel iv shows a representative image from transmission electron microscopy at an original magnification of ×3,000. Foot process effacement is observed without evidence of immune deposits. Scale bars represent 100 μm in light microscopy images and 5 μm in electron microscopy images. Values represent the mean ± SEM. *, p < 0.05 vs. “Coloboma only”. “RCS with PAX2 mutations” indicates clinically diagnosed renal-coloboma syndrome cases with PAX2 gene mutations (n = 5), “RCS without PAX2 mutations” indicates clinically diagnosed renal-coloboma syndrome cases without PAX2 gene mutations (n = 13), and “Coloboma only” indicates cases with optic nerve coloboma and no kidney abnormality (a disease control; n = 4).
Table 3.
Clinical manifestation of renal coloboma syndrome with/without PAX2 mutation.
Fig 3.
Optic nerve coloboma was severe in patients with PAX2 mutations.
Representative images of coloboma scores 0–4 are shown in panel A. Score 0, normal optic disc; Score 1, optic disc dysplasia with an unusual pattern of the retinal vessels and cilioretinal arteries; Score 2, optic disc pit associated with vascular abnormalities and a cilioretinal artery; Score 3, large coloboma involving the entire surface of the optic disc; Score 4, large coloboma of the optic disc and adjacent retina, or morning glory anomaly (with radial emergence of the retinal vessels). The mean coloboma scores of each group are shown in panel B. The coloboma scores (total, right and left eye) were significantly higher in patients with PAX2 mutations. Values represent the mean ± SEM. *, p < 0.05 vs. coloboma scores of patients without PAX2 mutations. “RCS with PAX2 mutations” indicates clinically diagnosed renal-coloboma syndrome cases with PAX2 gene mutations (n = 11), “RCS without PAX2 mutations” indicates clinically diagnosed renal-coloboma syndrome cases without PAX2 gene mutations (n = 15), and “Coloboma only” indicates cases with optic nerve coloboma and no kidney abnormality (a disease control; n = 4).
Fig 4.
Pedigree of the family with RCS with PAX2 mutations.
Pedigree of the family with RCS showing classical autosomal dominant inheritance across three generations. ☐, males; ❍, females; ●, female patients receiving hemodialysis. A diagonal line through a symbol means a patient is deceased.Ocular fundal images of Patient 1 (B, C) indicate that she had ocular coloboma (coloboma scores: right eye = 1, left eye = 3). Cross-sectional images of the optic disc acquired using optical coherence tomography (OCT) show deep excavation in both eyes (C).