Whole-exome resequencing reveals recessive mutations in TRAP1 in individuals with CAKUT and VACTERL association

Multicystic dysplastic kidney (MCDK) is one of the most common fetal malformations, but its etiology remains unclear. Identification of the molecular etiology could provide a basis for prenatal diagnosis, consultation, and prognosis evaluation for MCDK fetuses. We used chromosome microarray analysis (CMA) and whole-exome sequencing (WES) to conduct genetic tests on MCDK fetuses and explore their genetic etiology. A total of 108 MCDK fetuses with or without other extrarenal abnormalities were selected. Karyotype analysis of 108 MCDK fetuses showed an abnormal karyotype in 4 (3.7%, 4/108) of the fetuses. However, CMA detected 15 abnormal copy number variations (CNVs) (14 pathogenic CNVs, and one variant of unknown significance [VUS] CNVs), in addition to four cases that were consistent with the results of karyotype analysis. Out of the 14 pathogenic CNVs cases, three were of 17q12 microdeletion, two of 22q11.21 microdeletion, 22q11.21 microduplication uniparental disomy (UPD), and one case of 4q31.3q32.2 microdeletion, 7q11.23 microduplication, 15q11.2 microdeletion, 16p11.2 microdeletion, and 17p12 microdeletion. Of the 89 MCDK fetuses with normal karyotype analysis and CMA, 15 were tested by WES. Two (13.3%, 2/15) fetuses were identified by WES as Bardet-Biedl syndrome (BBS) 1 and BBS2. Combined application of CMA-WES to detect MCDK fetuses can significantly improve the detection rate of genetic etiology, providing a basis for consultation, and prognosis evaluation.

Editorial: Safety of Tumor Necrosis Factor Inhibitors in Pregnancy.

Prenatal diagnosis of persistent left superior vena cava, polyhydramnios and a small gastric bubble in a fetus with VACTERL association

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common reason for chronic kidney disease in children. Although more than 30 monogenic causes have been implicated in isolated forms of human CAKUT so far, the vast majority remains elusive. To identify novel monogenic causes of CAKUT we applied homozygosity mapping, together with whole exome sequencing, in a patient from consanguineous descent with isolated CAKUT. We identified a homozygous missense mutation (p.Arg415His) of the Ets Translocation Variant Gene 4 (ETV4). The transcription factor ETV4 is a downstream target of the GDNF/RET signaling pathway that plays a crucial role in kidney development. We show by means of electrophoretic mobility shift assay that the Arg415His mutant causes loss of the DNA binding affinity of ETV4 and fails to activate transcription in a cell-based luciferase reporter assay. We furthermore investigated the impact of the mutant protein on cell migration rate. Unlike wildtype ETV4, the Arg415His mutant failed to rescue cell migration defects observed in two ETV4 knock-down cell-lines. We therefore identified and functionally characterized a recessive mutation in ETV4 in a human patient with CAKUT. We hypothesize that the pathomechanism of this mutation could be via loss of the transcriptional function of ETV4, and a resulting abrogation of GDNF/RET/ETV4 signaling pathway.

The definition of congenital anomalies of the kidney and urinary tract (CAKUT) is the disease of structural malformations in the kidney and/or urinary tract containing vesicoureteral reflux (VUR). These anomalies can cause pediatric chronic kidney disease. However, the pathogenesis of CAKUT is not well understood, because identifying the genetic architecture of CAKUT is difficult due to the phenotypic heterogeneity and multifactorial genetic penetrance. We describe the current genetic basis and mechanisms of CAKUT including VUR via approaching the steps and signaling pathways of kidney developmental processes. We also focus on the newly developed strategies and challenges to fully address the role of the associated genes in the pathogenesis of the disease.

VACTERL association (OMIM 192350) is a heterogeneous clinical condition characterized by congenital structural defects that include at least 3 of the following features: vertebral abnormalities, anal atresia, heart defects, tracheoesophageal fistula, renal malformations, and limb defects. The nonrandom occurrence of these malformations and some familial cases suggest a possible association with genetic factors such as chromosomal alterations, gene mutations, and inherited syndromes such as Fanconi anemia (FA). In this study, the clinical phenotype and its relationship with the presence of chromosomal abnormalities and FA were evaluated in 18 patients with VACTERL association. For this, a G-banded karyotype, array-comparative genomic hybridization, and chromosomal fragility test for FA were performed. All patients (10 female and 8 male) showed a broad clinical spectrum: 13 (72.2%) had vertebral abnormalities, 8 (44.4%) had anal atresia, 14 (77.8%) had heart defects, 8 (44.4%) had esophageal atresia, 10 (55.6%) had renal abnormalities, and 10 (55.6%) had limb defects. Chromosomal abnormalities and FA were ruled out. In 2 cases, the finding of microalterations, namely del(15)(q11.2) and dup(17)(q12), explained the phenotype; in 8 cases, copy number variations were classified as variants of unknown significance and as not yet described in VACTERL. These variants comprise genes related to important cellular functions and embryonic development.

VACTERL association is a condition involving the presence of multiple congenital anomalies. The condition was first described more than four decades ago, and is not extremely rare. However, relatively little is understood about the causes and underlying biology of the condition as a whole. There are many reasons for this, but there is increasing recognition that VACTERL is extremely clinically as well as etiologically heterogeneous, and this heterogeneity--as well as other hypothesized factors--have caused challenges to identifying the causes for a substantial proportion of patients. Current knowledge about the causes of this condition (or group of conditions) are described, followed by a discussion of possibilities that may reveal more answers for patients as well as researchers and clinicians who work related to this disorder.

Multidisciplinary approaches for elucidating genetics and molecular pathogenesis of urinary tract malformations

Hsp90 as a therapeutic target in endocrinology: current evidence Thomas Ratajczak,1,2 Bryan Kenneth Ward,1,2 John Peter Walsh,2,3 Carmel Cluning1,2 1Laboratory for Molecular Endocrinology, Harry Perkins Institute of Medical Research and The UWA Centre for Medical Research, The University of Western Australia, 2Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Hospital Avenue, 3School of Medicine and Pharmacology, The University of Western Australia, Nedlands, WA, Australia Abstract: The ability of heat shock protein 90 (Hsp90) to modulate many growth and signaling pathways simultaneously makes it an attractive target in the field of cancer therapeutics and provided the initial impetus for significant efforts over the past decade to identify Hsp90 inhibitors, several of which are now showing promise in the clinic for cancer treatment. The four known human Hsp90 members are compartmentalized: Hsp90α and ß in the cytoplasm, GRP94 in the endoplasmic reticulum, and TRAP1 in the mitochondrial matrix. While these isoforms share a similar N-terminal domain adenosine triphosphate-binding pocket, structural variations allow unique interactions for inhibitors targeting this binding site, providing an avenue for the development of paralog-selective drugs with different biological effects applicable therapeutically to a wide range of diseases. At the same time, the conformational flexibility of the Hsp90 molecular chaperone has unveiled multiple small-molecule target sites within all subdomains of the protein, greatly expanding opportunities for viable drug development. This review summarizes the function, expression, and clinical significance of the Hsp90 isoforms and elaborates on the inhibitors and modulators that impact Hsp90 chaperone activity. Finally, the review focuses on the therapeutic utility of a range of Hsp90-modulating agents in the treatment of specific diseases associated with the endocrine system. Keywords: heat shock protein 90, GRP94, TRAP1, Hsp90 inhibitors, endocrine disorders

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most prevalent cause of kidney disease in the first three decades of life. Previous gene panel studies showed monogenic causation in up to 12% of patients with CAKUT. We applied whole-exome sequencing to analyze the genotypes of individuals from 232 families with CAKUT, evaluating for mutations in single genes known to cause human CAKUT and genes known to cause CAKUT in mice. In consanguineous or multiplex families, we additionally performed a search for novel monogenic causes of CAKUT. In 29 families (13%), we detected a causative mutation in a known gene for isolated or syndromic CAKUT that sufficiently explained the patient's CAKUT phenotype. In three families (1%), we detected a mutation in a gene reported to cause a phenocopy of CAKUT. In 15 of 155 families with isolated CAKUT, we detected deleterious mutations in syndromic CAKUT genes. Our additional search for novel monogenic causes of CAKUT in consanguineous and multiplex families revealed a potential single, novel monogenic CAKUT gene in 19 of 232 families (8%). We identified monogenic mutations in a known human CAKUT gene or CAKUT phenocopy gene as the cause of disease in 14% of the CAKUT families in this study. Whole-exome sequencing provides an etiologic diagnosis in a high fraction of patients with CAKUT and will provide a new basis for the mechanistic understanding of CAKUT.