PMC8702958_01
Patient's familial pedigree. The index case is indicated by the blue arrow.
fmed-08-795216-g0002.jpg
PMC8702958_01_fmed-08-795216-g0002.jpg
F2
The genealogical tree (Figure 2) showed several loops of consanguinity predisposing to recessive disease.
Periodic acid Schiff (PAS) stain at x20 magnification on light microscopy showing a normal glomerulus (arrow).
fmed-08-795216-g0003.jpg
PMC8702958_01_fmed-08-795216-g0003.jpg
F3
Light microscopy (Figure 3) showed six glomeruli, five of which were within normal limits while one presented advanced sclerosis.
Periodic acid Schiff (PAS) stain at x20 magnification on light microscopy showing a mild interstitial fibrosis and tubular atrophy. One glomerulus out of 6 showed a complete sclerosis (arrow). Arteries showed a moderate arteriosclerosis (arrowhead).
fmed-08-795216-g0004.jpg
PMC8702958_01_fmed-08-795216-g0004.jpg
F4
Arteries showed moderate arteriosclerosis (Figure 4).
(A) Presence of the c.626C>T p.(Pro209Leu) variant (green block) at homozygous state in exon 6 of the TTC21B gene found through clinical exome sequencing and visualized in Integrative Genomics Viewer (IGV). (B) Presence of the variant at homozygous state in the patient and her cousin was confirmed by Sanger sequencing.
fmed-08-795216-g0005.jpg
PMC8702958_01_fmed-08-795216-g0005.jpg
F5
TTC21B gene (NM_024753.5) (Figure 5A). Sanger sequencing in the patient and her cousin who developed ESRD (Figure 5B). This variant is present with a frequency of 0.012% (34/282510 alleles) and has never been seen in the homozygous state in the gnomAD frequency database (https://gnomad.broadinstitute.org/). Several prediction tools (SIFT,