Dataset Information

Phenotype expansion of heterozygous FOXC1 pathogenic variants toward involvement of congenital anomalies of the kidneys and urinary tract (CAKUT).

ABSTRACT:

Purpose

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in childhood and adolescence. We aim to identify novel monogenic causes of CAKUT.

Methods

Exome sequencing was performed in 550 CAKUT-affected families.

Results

We discovered seven FOXC1 heterozygous likely pathogenic variants within eight CAKUT families. These variants are either never reported, or present in <5 alleles in the gnomAD database with ~141,456 controls. FOXC1 is a causal gene for Axenfeld-Rieger syndrome type 3 and anterior segment dysgenesis 3. Pathogenic variants in FOXC1 have not been detected in patients with CAKUT yet. Interestingly, mouse models for Foxc1 show severe CAKUT phenotypes with incomplete penetrance and variable expressivity. The FOXC1 variants are enriched in the CAKUT cohort compared with the control. Genotype-phenotype correlations showed that Axenfeld-Rieger syndrome or anterior segment dysgenesis can be caused by both truncating and missense pathogenic variants, and the missense variants are located at the forkhead domain. In contrast, for CAKUT, there is no truncating pathogenic variant, and all variants except one are located outside the forkhead domain.

Conclusion

We thereby expanded the phenotype of FOXC1 pathogenic variants toward involvement of CAKUT, which can potentially be explained by allelism.

SUBMITTER: Wu CW

PROVIDER: S-EPMC8220407 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundCongenital anomalies of the kidney and urinary tract (CAKUT) are the predominant cause for chronic kidney disease below 30 years of age. Many monogenic forms have been discovered mainly due to comprehensive genetic testing like exome sequencing (ES). However, disease-causing variants in known disease-associated genes still only explain a proportion of cases. Aim of this study was to unravel the underlying molecular mechanism of syndromic CAKUT in two multiplex families with presumed autosomal recessive inheritance.Methods and resultsES in the index individuals revealed two different rare homozygous variants in FOXD2, a transcription factor not previously implicated in CAKUT in humans: a frameshift in family 1 and a missense variant in family 2 with family segregation patterns consistent with autosomal-recessive inheritance. CRISPR/Cas9-derived Foxd2 knock-out (KO) mice presented with bilateral dilated renal pelvis accompanied by renal papilla atrophy while extrarenal features included mandibular, ophthalmologic, and behavioral anomalies, recapitulating the phenotype of humans with FOXD2 dysfunction. To study the pathomechanism of FOXD2-dysfunction-mediated developmental renal defects, in a complementary approach, we generated CRISPR/Cas9-mediated KO of Foxd2 in ureteric-bud-induced mouse metanephric mesenchyme cells. Transcriptomic analyses revealed enrichment of numerous differentially expressed genes important in renal/urogenital development, including Pax2 and Wnt4 as well as gene expression changes indicating a cell identity shift towards a stromal cell identity. Histology of Foxd2 KO mouse kidneys confirmed increased fibrosis. Further, GWAS data (genome-wide association studies) suggests that FOXD2 could play a role for maintenance of podocyte integrity during adulthood.ConclusionsIn summary, our data implicate that FOXD2 dysfunction is a very rare cause of autosomal recessive syndromic CAKUT and suggest disturbances of the PAX2-WNT4 cell signaling axis contribute to this phenotype.