Whole exome sequencing identifies a mutation in EYA1 and GLI3 in a patient with branchio-otic syndrome and esophageal atresia: Coincidence or a digenic mode of inheritance?

Branchio-otic (BO) syndrome is a clinically and genetically heterogeneous disorder that presents with variable branchial arch and otic anomalies. Dominant mutations in the human homologues of the Drosophila eyes absent (EYA1) gene, and the Drosophila sine oculis homeobox 1 and 5 (SIX1 and SIX5, respectively) genes have been causally associated with BO syndrome. Esophageal atresia (EA), with or without tracheo-esophageal fistula (TEF), is the most common type of malformation of the upper digestive tract. To date, its causes are poorly understood. The present study investigated a family with three affected members who all presented with classic BO associated symptoms. Notably, the index patient also presented with the most common EA/TEF subtype type 3b. Whole exome sequencing (WES) was performed in the index patient, and prioritized genetic variants and their segregation in the family were analyzed by Sanger sequencing. WES demonstrated a known disease-causing heterozygous EYA1 splice variant in the patient, as well as his sister and mother; all of whom were affected with BO syndrome. A further GLI family zinc finger 3 (GLI3) splice variant of unknown significance, inherited from the unaffected father, was also detected in the index patient. EYA1 and GLI3 are involved in the Sonic Hedgehog transcriptional network and GLI3 seems to be involved in human foregut malformations. Therefore, one may hypothesize a digenic inheritance model involving EYA1 and GLI3, where the effect of the GLI3 variant observed here only emerges in the background of the EYA1 defect

HSPA6: A new autosomal recessive candidate gene for the VATER/VACTERL malformation spectrum

Background The VATER/VACTERL association refers to the nonrandom co-occurrence of at least three of the following component features (CFs): vertebral defects (V), anorectal malformations (ARM) (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb defects (L). Patients presenting with two CFs have been termed VATER/VACTERL-like phenotypes. Methods We surveyed the exome for recessive disease variants in three affected sib-pairs. Sib-pair 971 consisted of two brothers with ARM and additional hydronephrosis in one brother. Sib-pair 1098 consisted of two sisters with ARM. In family 1346, the daughter presented with ARM and additional hypoplasia of both small fingers and ankyloses. Her brother presented with unilateral isolated radial hypoplasia. Sib-pairs 971 and 1346 resembled a VATER/VACTERL-like phenotype. Results We detected a novel maternally inherited missense variant (c.1340G > T) and a rare paternally inherited deletion of the trans-allele in HSPA6 in both siblings of family 1346. HSPA6 belongs to the heat shock protein (HSP) 70 family. Re-sequencing of HSPA6 in 167 patients with VATER/VACTERL and VATER/VACTERL-like phenotypes did not reveal any additional bi-allelic variants. Conclusions Until now, only TNF-receptor associated protein 1 (TRAP1) had been reported as an autosomal recessive disease-gene for the VATER/VACTERL association. TRAP1 belongs to the heat shock protein 90 family (HSP90). Both Hsp70 and Hsp90 genes have been shown to be important embryonic drivers in the formation of mouse embryonic forelimb tissue. Our results suggest HSPA6 as a new candidate gene in VATER/VACTERL-like phenotypes

Array-based molecular karyotyping in 115 VATER/VACTERL and VATER/VACTERL-like patients identifies disease-causing copy number variations

BackgroundThe acronym VATER/VACTERL refers to the rare nonrandom association of the following component features (CF): vertebral defects (V), anorectal malformations (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia, renal malformations (R), and limb defects (L). Patients presenting with at least three CFs are diagnosed as having VATER/VACTERL association while patients presenting with only two CFs are diagnosed as having VATER/VACTERL-like phenotypes. Recently, rare causative copy number variations (CNVs) have been identified in patients with VATER/VACTERL association and VATER/VACTERL-like phenotypes. MethodsTo detect further causative CNVs we performed array based molecular karyotyping in 75 VATER/VACTERL and 40 VATER/VACTERL-like patients. ResultsFollowing the application of stringent filter criteria, we identified 13 microdeletions and seven microduplications in 20 unrelated patients all of which were absent in 1,307 healthy inhouse controls (n < 0.0008). Among these, microdeletion at 17q12 was confirmed to be de novo. Three microdeletions at 5q23.1, 16q23.3, 22q11.21, and one microduplication at 10q11.21 were all absent in the available parent. Microdeletion of chromosomal region 22q11.21 was previously found in VATER/VACTERL patients rendering it to be causative in our patient. The remaining 15 CNVs were inherited from a healthy parent. ConclusionIn two of 115 patients' causative CNVs were found (2%). The remaining identified rare CNVs represent candidates for further evaluation. Rare inherited CNVs may constitute modifiers of, or contributors to, multifactorial VATER/VACTERL or VATER/VACTERL-like phenotypes. Birth Defects Research 109:1063-1069, 2017. (c) 2017 Wiley Periodicals, Inc

Array-based molecular karyotyping in 115 VATER/VACTERL and VATER/VACTERL-like patients identifies disease-causing copy number variations

BackgroundThe acronym VATER/VACTERL refers to the rare nonrandom association of the following component features (CF): vertebral defects (V), anorectal malformations (A), cardiac defects (C), tracheoesophageal fistula with or without esophageal atresia, renal malformations (R), and limb defects (L). Patients presenting with at least three CFs are diagnosed as having VATER/VACTERL association while patients presenting with only two CFs are diagnosed as having VATER/VACTERL-like phenotypes. Recently, rare causative copy number variations (CNVs) have been identified in patients with VATER/VACTERL association and VATER/VACTERL-like phenotypes. MethodsTo detect further causative CNVs we performed array based molecular karyotyping in 75 VATER/VACTERL and 40 VATER/VACTERL-like patients. ResultsFollowing the application of stringent filter criteria, we identified 13 microdeletions and seven microduplications in 20 unrelated patients all of which were absent in 1,307 healthy inhouse controls (n < 0.0008). Among these, microdeletion at 17q12 was confirmed to be de novo. Three microdeletions at 5q23.1, 16q23.3, 22q11.21, and one microduplication at 10q11.21 were all absent in the available parent. Microdeletion of chromosomal region 22q11.21 was previously found in VATER/VACTERL patients rendering it to be causative in our patient. The remaining 15 CNVs were inherited from a healthy parent. ConclusionIn two of 115 patients' causative CNVs were found (2%). The remaining identified rare CNVs represent candidates for further evaluation. Rare inherited CNVs may constitute modifiers of, or contributors to, multifactorial VATER/VACTERL or VATER/VACTERL-like phenotypes. Birth Defects Research 109:1063-1069, 2017. (c) 2017 Wiley Periodicals, Inc

CAKUT and autonomic dysfunction caused by acetylcholine receptor mutations

Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of chronic kidney disease in the first three decades of life, and in utero obstruction to urine flow is a frequent cause of secondary upper urinary tract malformations. Here, using whole-exome sequencing, we identified three different biallelic mutations in CHRNA3, which encodes the α3 subunit of the nicotinic acetylcholine receptor, in five affected individuals from three unrelated families with functional lower urinary tract obstruction and secondary CAKUT. Four individuals from two families have additional dysautonomic features, including impaired pupillary light reflexes. Functional studies in vitro demonstrated that the mutant nicotinic acetylcholine receptors were unable to generate current following stimulation with acetylcholine. Moreover, the truncating mutations p.Thr337Asnfs∗81 and p.Ser340∗ led to impaired plasma membrane localization of CHRNA3. Although the importance of acetylcholine signaling in normal bladder function has been recognized, we demonstrate for the first time that mutations in CHRNA3 can cause bladder dysfunction, urinary tract malformations, and dysautonomia. These data point to a pathophysiologic sequence by which monogenic mutations in genes that regulate bladder innervation may secondarily cause CAKUT

Rare Variants in BNC2 Are Implicated in Autosomal-Dominant Congenital Lower Urinary-Tract Obstruction

Congenital lower urinary-tract obstruction (LUTO) is caused by anatomical blockage of the bladder outflow tract or by functional impairment of urinary voiding. About three out of 10,000 pregnancies are affected. Although several monogenic causes of functional obstruction have been defined, it is unknown whether congenital LUTO caused by anatomical blockage has a monogenic cause. Exome sequencing in a family with four affected individuals with anatomical blockage of the urethra identified a rare nonsense variant (c.2557C>T [p.Arg853*]) in BNC2, encoding basonuclin 2, tracking with LUTO over three generations. Resequencing BNC2 in 697 individuals with LUTO revealed three further independent missense variants in three unrelated families. In human and mouse embryogenesis, basonuclin 2 was detected in lower urinary-tract rudiments. In zebrafish embryos, bnc2 was expressed in the pronephric duct and cloaca, analogs of the mammalian lower urinary tract. Experimental knockdown of Bnc2 in zebrafish caused pronephric-outlet obstruction and cloacal dilatation, phenocopying human congenital LUTO. Collectively, these results support the conclusion that variants in BNC2 are strongly implicated in LUTO etiology as a result of anatomical blockage

Mutations of the Transcriptional Corepressor ZMYM2 Cause Syndromic Urinary Tract Malformations

International audienceCongenital anomalies of the kidney and urinary tract (CAKUT) constitute one of the most frequent birth defects and represent the most common cause of chronic kidney disease in the first three decades of life. Despite the discovery of dozens of monogenic causes of CA-KUT, most pathogenic pathways remain elusive. We performed whole-exome sequencing (WES) in 551 individuals with CAKUT and identified a heterozygous de novo stop-gain variant in ZMYM2 in two different families with CAKUT. Through collaboration, we identified in total 14 different heterozygous loss-of-function mutations in ZMYM2 in 15 unrelated families. Most mutations occurred de novo, indicating possible interference with reproductive function. Human disease features are replicated in X. tropicalis larvae with morpho-lino knockdowns, in which expression of truncated ZMYM2 proteins, based on individual mutations, failed to rescue renal and cranio-facial defects. Moreover, heterozygous Zmym2-deficient mice recapitulated features of CAKUT with high penetrance. The ZMYM2 protein is a component of a transcriptional corepressor complex recently linked to the silencing of developmentally regulated endoge-nous retrovirus elements. Using protein-protein interaction assays, we show that ZMYM2 interacts with additional epigenetic silencing complexes, as well as confirming that it binds to FOXP1, a transcription factor that has also been linked to CAKUT. In summary, our findings establish that loss-of-function mutations of ZMYM2, and potentially that of other proteins in its interactome, as causes of human CAKUT, offering new routes for studying the pathogenesis of the disorder