@article {954, title = {Human and mouse studies establish TBX6 in Mendelian CAKUT and as a potential driver of kidney defects associated with the 16p11.2 microdeletion syndrome.}, journal = {Kidney Int}, volume = {98}, year = {2020}, month = {2020 10}, pages = {1020-1030}, abstract = {

Congenital anomalies of the kidney and urinary tract (CAKUTs) are the most common cause of chronic kidney disease in children. Human 16p11.2 deletions have been associated with CAKUT, but the responsible molecular mechanism remains to be illuminated. To explore this, we investigated 102 carriers of 16p11.2 deletion from multi-center cohorts, among which we retrospectively ascertained kidney morphologic and functional data from 37 individuals (12 Chinese and 25 Caucasian/Hispanic). Significantly higher CAKUT rates were observed in 16p11.2 deletion carriers (about 25\% in Chinese and 16\% in Caucasian/Hispanic) than those found in the non-clinically ascertained general populations (about 1/1000 found at autopsy). Furthermore, we identified seven additional individuals with heterozygous loss-of-function variants in TBX6, a gene that maps to the 16p11.2 region. Four of these seven cases showed obvious CAKUT. To further investigate the role of TBX6 in kidney development, we engineered mice with mutated Tbx6 alleles. The Tbx6 heterozygous null (i.e., loss-of-function) mutant (Tbx6) resulted in 13\% solitary kidneys. Remarkably, this incidence increased to 29\% in a compound heterozygous model (Tbx6) that reduced Tbx6 gene dosage to below haploinsufficiency, by combining the null allele with a novel mild hypomorphic allele (mh). Renal hypoplasia was also frequently observed in these Tbx6-mutated mouse models. Thus, our findings in patients and mice establish TBX6 as a novel gene involved in CAKUT and its gene dosage insufficiency as a potential driver for kidney defects observed in the 16p11.2 microdeletion syndrome.

}, issn = {1523-1755}, doi = {10.1016/j.kint.2020.04.045}, author = {Yang, Nan and Wu, Nan and Dong, Shuangshuang and Zhang, Ling and Zhao, Yanxue and Chen, Weisheng and Du, Renqian and Song, Chengcheng and Ren, Xiaojun and Liu, Jiaqi and Pehlivan, Davut and Liu, Zhenlei and Rao, Jia and Wang, Chunyan and Zhao, Sen and Breman, Amy M and Xue, Huadan and Sun, Hao and Shen, Jianxiong and Zhang, Shuyang and Posey, Jennifer E and Xu, Hong and Jin, Li and Zhang, Jianguo and Liu, Pengfei and Sanna-Cherchi, Simone and Qiu, Guixing and Wu, Zhihong and Lupski, James R and Zhang, Feng} } @article {977, title = {Phenotype expansion of heterozygous FOXC1 pathogenic variants toward involvement of congenital anomalies of the kidneys and urinary tract (CAKUT).}, journal = {Genet Med}, volume = {22}, year = {2020}, month = {2020 10}, pages = {1673-1681}, 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.

}, keywords = {Child, Eye Abnormalities, Forkhead Transcription Factors, Heterozygote, Humans, Kidney, Phenotype, Urinary Tract}, issn = {1530-0366}, doi = {10.1038/s41436-020-0844-z}, author = {Wu, Chen-Han Wilfred and Mann, Nina and Nakayama, Makiko and Connaughton, Dervla M and Dai, Rufeng and Kolvenbach, Caroline M and Kause, Franziska and Ottlewski, Isabel and Wang, Chunyan and Kl{\"a}mbt, Verena and Seltzsam, Steve and Lai, Ethan W and Selvin, Aravind and Senguttuva, Prabha and Bodamer, Olaf and Stein, Deborah R and El Desoky, Sherif and Kari, Jameela A and Tasic, Velibor and Bauer, Stuart B and Shril, Shirlee and Hildebrandt, Friedhelm} }