PIEZO1 loss-of-function compound heterozygous mutations in the rare congenital human disorder Prune Belly Syndrome.

Prune belly syndrome (PBS), also known as Eagle-Barret syndrome, is a rare, multi-system congenital myopathy primarily affecting males. Phenotypically, PBS cases manifest three cardinal pathological features: urinary tract dilation with poorly contractile smooth muscle, wrinkled flaccid ventral abdominal wall with skeletal muscle deficiency, and intra-abdominal undescended testes. Genetically, PBS is poorly understood. After performing whole exome sequencing in PBS patients, we identify one compound heterozygous variant in the PIEZO1 gene. PIEZO1 is a cation-selective channel activated by various mechanical forces and widely expressed throughout the lower urinary tract. Here we conduct an extensive functional analysis of the PIEZO1 PBS variants that reveal loss-of-function characteristics in the pressure-induced normalized open probability (NPo) of the channel, while no change is observed in single-channel currents. Furthermore, Yoda1, a PIEZO1 activator, can rescue the NPo defect of the PBS mutant channels. Thus, PIEZO1 mutations may be causal for PBS and the in vitro cellular pathophysiological phenotype could be rescued by the small molecule, Yoda1. Activation of PIEZO1 might provide a promising means of treating PBS and other related bladder dysfunctional states.

Prune belly syndrome in surviving males can be caused by Hemizygous missense mutations in the X-linked Filamin A gene.

BACKGROUND: Prune belly syndrome (PBS) is a rare, multi-system congenital myopathy primarily affecting males that is poorly described genetically. Phenotypically, its morbidity spans from mild to lethal, however, all isolated PBS cases manifest three cardinal pathological features: 1) wrinkled flaccid ventral abdominal wall with skeletal muscle deficiency, 2) urinary tract dilation with poorly contractile smooth muscle, and 3) intra-abdominal undescended testes. Despite evidence for a genetic basis, previously reported PBS autosomal candidate genes only account for one consanguineous family and single cases. METHODS: We performed whole exome sequencing (WES) of two maternal adult half-brothers with syndromic PBS (PBS + Otopalatodigital spectrum disorder [OPDSD]) and two unrelated sporadic individuals with isolated PBS and further functionally validated the identified mutations. RESULTS: We identified three unreported hemizygous missense point mutations in the X-chromosome gene Filamin A (FLNA) (c.4952 C > T (p.A1448V), c.6727C > T (p.C2160R), c.5966 G > A (p.G2236E)) in two related cases and two unrelated sporadic individuals. Two of the three PBS mutations map to the highly regulatory, stretch-sensing Ig19-21 region of FLNA and enhance binding to intracellular tails of the transmembrane receptor ß-integrin 1 (ITGß1). CONCLUSIONS: FLNA is a regulatory actin-crosslinking protein that functions in smooth muscle cells as a mechanosensing molecular scaffold, transmitting force signals from the actin-myosin motor units and cytoskeleton via binding partners to the extracellular matrix. This is the first evidence for an X-linked cause of PBS in multiple unrelated individuals and expands the phenotypic spectrum associated with FLNA in males surviving even into adulthood.

Copy number variations in a population with prune belly syndrome.

Prune Belly Syndrome (PBS) is a congenital multisystem myopathy with mild to lethal severity. While of uncertain etiology, 95% male predominance and familial occurrence suggest a genetic basis. As copy number variations (CNVs) can cause unexplained genetic disorders, we tested for novel CNVs in a large PBS population. We genotyped 21 unrelated PBS patients by high-resolution array comparative genomic hybridization (aCGH) and phenotyped using a novel PBS severity scoring system. Available parents were screened for detected CNV via quantitative PCR (qPCR). We additionally screened for recurrence of identified novel candidate CNVs on 106 PBS probands by qPCR. We identified 10 CNVs in 8 of 21 PBS patients tested (38%). Testing confirmed inheritance from an unaffected biological parent in six patients; parental samples were unavailable in two probands. One candidate CNV includes duplication of the X-chromosome AGTR2 gene, known to function in urinary tract development. Subsequent screening of the larger PBS cohort did not identify any recurrent CNVs. Presence of CNV did not correlate with PBS severity scoring. CNVs were uncommon in this large PBS population, but analysis of identified variants may inform disease pathogenesis and reveal targets for therapeutic intervention for this rare, severe disorder.

Rare copy number variants identified in prune belly syndrome.

Prune belly syndrome (PBS), also known as Eagle-Barrett syndrome, is a rare congenital disorder characterized by absence or hypoplasia of the abdominal wall musculature, urinary tract anomalies, and cryptorchidism in males. The etiology of PBS is largely unresolved, but genetic factors are implicated given its recurrence in families. We examined cases of PBS to identify novel pathogenic copy number variants (CNVs). A total of 34 cases (30 males and 4 females) with PBS identified from all live births in New York State (1998-2005) were genotyped using Illumina HumanOmni2.5 microarrays. CNVs were prioritized if they were absent from in-house controls, encompassed ≥10 consecutive probes, were ≥20 Kb in size, had ≤20% overlap with common variants in population reference controls, and had ≤20% overlap with any variant previously detected in other birth defect phenotypes screened in our laboratory. We identified 17 candidate autosomal CNVs; 10 cases each had one CNV and four cases each had two CNVs. The CNVs included a 158 Kb duplication at 4q22 that overlaps the BMPR1B gene; duplications of different sizes carried by two cases in the intron of STIM1 gene; a 67 Kb duplication 202 Kb downstream of the NOG gene, and a 1.34 Mb deletion including the MYOCD gene. The identified rare CNVs spanned genes involved in mesodermal, muscle, and urinary tract development and differentiation, which might help in elucidating the genetic contribution to PBS. We did not have parental DNA and cannot identify whether these CNVs were de novo or inherited. Further research on these CNVs, particularly BMP signaling is warranted to elucidate the pathogenesis of PBS.

A homozygous loss-of-function variant in MYH11 in a case with megacystis-microcolon-intestinal hypoperistalsis syndrome.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is characterized by marked dilatation of the bladder and microcolon and decreased intestinal peristalsis. Recent studies indicate that heterozygous variants in ACTG2, which codes for a smooth muscle actin, cause MMIHS. However, such variants do not explain MMIHS cases that show an autosomal recessive mode of inheritance. We performed exome sequencing in a newborn with MMIHS and prune belly phenotype whose parents are consanguineous and identified a homozygous variant (c.3598A>T: p.Lys1200Ter) in MYH11, which codes for the smooth muscle myosin heavy chain. Previous studies showed that loss of Myh11 function in mice causes a bladder and intestinal phenotype that is highly reminiscent of MMIHS. All together, these observations strongly suggest that loss-of-function variants in MYH11 cause MMIHS. The documentation of variants in ACTG2 and MYH11 thus points to the involvement of the contractile apparatus of the smooth muscle in MMIHS. Interestingly, dominant-negative variants in MYH11 have previously been shown to cause thoracic aortic aneurism and dilatation. Different mechanisms of MYH11 disruption may thus lead to distinct patterns of smooth muscle dysfunction.

Congenital mydriasis and prune belly syndrome in a child with an ACTA2 mutation.

We report the association of congenital mydriasis with prune belly syndrome and cerebrovascular anomalies in a 9-year-old boy who was found to have an ACTA2 mutation. This case illustrates the spectrum of systemic malformations that are attributable to mutations in ACTA2 and expands the spectrum of cerebrovascular anomalies that are now known to accompany congenital mydriasis.

[Prune-Belly Syndrome: a case report]. / Sindrome Prune-Belly: un caso clinico.

Prune-Belly Syndrome (PBS) is a rare congenital syndrome characterized by the absence of abdominal muscles, anomalies in the urinary tract, megaureter, cryptorchidism or testicular agenesis, hypertension and worsening chronic kidney disease (CKD). The incidence is estimated between 1 out of 35,000 and 1 out of 50,000 born alive, and it affects males in prevalence (97%). In the present study we describe the case of a 38 year old male patient (followed since May 2011) affected by PBS, CKD, one functional kidney at the scintigraphy, pediatric testicular implants, bladder surgery and correction of pectus excavatum. At the beginning of the observation, renal function was deteriorated, with a creatinine 3.3 mg/dl, GFR calculated at MDRD 23 ml/min, proteinuria in nephrotic range (4 g/day), high blood pressure, anemia and hyperparathyroidism. In the following examinations renal function framework worsened, despite the adoption of a low-protein diet. Due to the functional trend, the patient was prescribed hemodialysis as substitute treatment. In January 2013 a first attempt of artero-venous fistula (AVF) did not succeed, while a new AVF in March 2013 resulted effective. In July hemodialysis was started. In the future, we expect to insert the patient in the Kidney Transplant List (since surgical feasibility has already been positively evaluated). Our case is quite peculiar due to the late beginning of substitute treatment. Further, SPB represents a challenge that, in the absence of a prompt and effective treatment, inevitably it leads to terminal uremia; nevertheless, given a proper treatment, a transplant with good chances of success can be envisaged.

Genetics of human congenital urinary bladder disease.

Lower urinary tract and/or kidney malformations are collectively the most common cause of end-stage renal disease in children, and they are also likely to account for a major subset of young adults requiring renal replacement therapy. Advances have been made regarding the discovery of the genetic causes of human kidney malformations. Indeed, testing for mutations of key nephrogenesis genes is now feasible for patients seen in nephrology clinics. Unfortunately, less is known about defined genetic bases of human lower urinary tract anomalies. The focus of this review is the genetic bases of congenital structural and functional disorders of the urinary bladder. Three are highlighted. First, prune belly syndrome, where mutations of CHRM3, encoding an acetylcholine receptor, HNF1B, encoding a transcription factor, and ACTA2, encoding a cytoskeletal protein, have been reported. Second, the urofacial syndrome, where mutations of LRIG2 and HPSE2, encoding proteins localised in nerves invading the fetal bladder, have been defined. Finally, we review emerging evidence that bladder exstrophy may have genetic bases, including variants in the TP63 promoter. These genetic discoveries provide a new perspective on a group of otherwise poorly understood diseases.

Normal live births after intracytoplasmic sperm injection in a man with the rare condition of Eagle-Barrett syndrome (prune-belly syndrome).

OBJECTIVE: To report the first live births of male infants resulting from intracytoplasmic sperm injection (ICSI) using spermatozoa from a man with Eagle-Barrett syndrome (EBS). DESIGN: Case report. SETTING: Assisted conception unit within a private hospital. PATIENT(S): An infertile couple. INTERVENTIONS: An infertile couple received repeated treatment with ICSI. MAIN OUTCOME MEASURE(S): Clinical pregnancy and a normal live birth. RESULT(S): In 2008, after microinjection of ten oocytes, the transfer of a single expanded blastocyst led to the premature birth of a morphologically normal male infant at 18 weeks' gestation. This outcome followed preterm rupture of membranes and possible cervical incompetence. In 2009, after microinjection of six oocytes, transfer of a single 5-cell embryo led to a singleton pregnancy, with emergency cervical cerclage being performed at 21 weeks. A healthy male infant was born at 30 weeks, with no evidence of EBS, by lower-segment cesarean section for breech presentation and premature labor. In 2012, after elective laparoscopic placement of cervical suture, microinjection of ten oocytes and transfer of a single 4-cell embryo led to a singleton pregnancy with a healthy male infant, with no evidence of EBS, being born by cesarean section at 38 weeks. CONCLUSION(S): This report suggests that EBS is not transmitted to male offspring via ICSI.

Prune-belly syndrome: case series and review of the literature regarding early prenatal diagnosis, epidemiology, genetic factors, treatment, and prognosis.

Prune-belly syndrome (PBS) is a rare congenital syndrome characterized by deficient abdominal muscles, urinary tract malformation, and in males, cryptorchidism and has an estimated incidence of 1 in 35,000 to 1 in 50,000 live births. The syndrome might be due to severe bladder outlet obstruction or to abdominal muscle deficiency secondary to a migrational defect of the lateral mesoblast between weeks 6 and 7 of pregnancy. The current review of the medical record reports a special focus on epidemiology, genetic factors, early prenatal diagnosis clusters, treatment, and prognosis of PBS.

Familial prune belly syndrome in a Nigerian family.

A case of Prune Belly Syndrome in an infant, the second in a middle class family with both parents in their late thirties, is presented because of its rarity. Constraints in the management are discussed and relevant literature reviewed. This is intended to awaken interest and sharpen indices of suspicion that would facilitate early diagnosis, enhance management, and mitigate prejudices.

R179H mutation in ACTA2 expanding the phenotype to include prune-belly sequence and skin manifestations.

Mutations in ACTA2 (smooth muscle cell-specific isoform of α-actin) lead to a predisposition to thoracic aortic aneurysms and other vascular diseases. More recently, the ACTA2 R179H mutation has been described in individuals with global smooth muscle dysfunction. We report a patient heterozygous for the mutation in ACTA2 R179H who presented with megacystis at 13 weeks gestational age and, at birth, with prune-belly sequence. He also had deep skin dimples and creases on his palms and soles, a finding not previously described but possibly related to ACTA2. To our knowledge, this is the first report of the R179H mutation in ACTA2 in a child with prune-belly sequence. We think the R179H mutation in ACTA2 should be included in the differential diagnosis of individuals presenting with the sequence without an identified mechanical obstruction. Furthermore, as ACTA2 R179H has been reported in patients with severe vasculomyopathy and premature death, we recommend that molecular testing for this mutation be considered in fetuses presenting with fetal megacystis with a normal karyotype, particularly if the bladder diameter is 15 mm or more, to allow expectant parents to make an informed decision.

Recurrent Johanson-Blizzard syndrome in a triplet pregnancy complicated by urethral obstruction sequence: a clinical, molecular, and immunohistochemical approach.

We report on a triplet pregnancy of consanguineous parents with one fetus being affected by recurrent Johanson-Blizzard syndrome (JBS). At autopsy in the 35th gestational week, the affected triplet presented with an especially severe and lethal manifestation of the disorder as compared to his elder affected brother and to cases in the literature, thus exemplifying great interfamilial and intrafamilial phenotypic variability. Arhinencephaly and cystic renal dysplasia associated with urethral obstruction sequence were features not described previously in the literature. In addition to the lack of exocrine acini as the characteristic feature of JBS, the pancreas revealed a resorptive inflammatory reaction with infiltration by eosinophilic granulocytes that focally dispersed onto islets of Langerhans, thus favoring a progressive destructive rather than primary dysplastic process and possibly explaining the occurrence of diabetes mellitus in later life. JBS maps to chromosome 15q15-q21.1 and is associated with mutations in the UBR1 gene. Testing the fetus and the affected sibling revealed a homozygous truncating mutation in UBR1. The resulting absence of the UBR1 protein was confirmed by Western blot. Immunohistochemical staining using a commercial anti-UBR1 antibody demonstrated staining, presumably artifactual. This finding suggests that, until an appropriately validated antibody has been identified, this modality should not be utilized for diagnosis or confirmation of this disorder.

Genetic basis of prune belly syndrome: screening for HNF1ß gene.

PURPOSE: Although the cause of prune belly syndrome is unknown, familial evidence suggests a genetic component. Recently 2 nonfamilial cases of prune belly syndrome with chromosome 17q12 deletions encompassing the HNF1ß gene have made this a candidate gene for prune belly syndrome. To date, there has been no large-scale screening of patients with prune belly syndrome for HNF1ß mutations. We assessed the role of HNF1ß in prune belly syndrome by screening for genomic mutations with functional characterization of any detected mutations. MATERIALS AND METHODS: We studied patients with prune belly syndrome who were prospectively enrolled in our Pediatric Genitourinary DNA Repository since 2001. DNA from patient samples was amplified by polymerase chain reaction, sequenced for coding and splice regions of the HNF1ß gene, and compared to control databases. We performed functional assay testing of the ability of mutant HNF1ß to activate a luciferase construct with an HNF1ß DNA binding site. RESULTS: From 32 prune belly syndrome probands (30 males, 2 females) HNF1ß sequencing detected a missense mutation (V61G) in 1 child with prune belly syndrome. Absent in control databases, V61G was previously reported in 2 patients without prune belly syndrome who had congenital genitourinary anomalies. Functional testing showed similar luciferase activity compared to wild-type HNF1ß, suggesting the V61G substitution does not disturb HNF1ß function. CONCLUSIONS: One genomic HNF1ß mutation was detected in 3% of patients with prune belly syndrome but found to be functionally normal. Thus, functionally significant HNF1ß mutations are uncommon in prune belly syndrome, despite case reports of HNF1ß deletions. Further genetic study is necessary, as identification of the genetic basis of prune belly syndrome may ultimately lead to prevention and improved treatments for this rare but severe syndrome.

Muscarinic Acetylcholine Receptor M3 Mutation Causes Urinary Bladder Disease and a Prune-Belly-like Syndrome.

Urinary bladder malformations associated with bladder outlet obstruction are a frequent cause of progressive renal failure in children. We here describe a muscarinic acetylcholine receptor M3 (CHRM3) (1q41-q44) homozygous frameshift mutation in familial congenital bladder malformation associated with a prune-belly-like syndrome, defining an isolated gene defect underlying this sometimes devastating disease. CHRM3 encodes the M3 muscarinic acetylcholine receptor, which we show is present in developing renal epithelia and bladder muscle. These observations may imply that M3 has a role beyond its known contribution to detrusor contractions. This Mendelian disease caused by a muscarinic acetylcholine receptor mutation strikingly phenocopies Chrm3 null mutant mice.

Deletion of hepatocyte nuclear factor-1-beta in an infant with prune belly syndrome.

Prune belly syndrome is a rare congenital disorder characterized by deficiency of abdominal wall muscles, cryptorchidism, and urinary tract anomalies. We have had the opportunity to study a baby with prune belly syndrome associated with an apparently de novo 1.3-megabase interstitial 17q12 microdeletion that includes the hepatocyte nuclear factor-1-beta gene at 17q12. One previous patient, an adult, has been reported with prune belly syndrome and a hepatocyte nuclear factor-1-beta microdeletion. Hepatocyte nuclear factor-1-beta is a widely expressed transcription factor that regulates tissue-specific gene expression and is expressed in numerous tissues including mesonephric duct derivatives, the renal tubule of the metanephros, and the developing prostate of the mouse. Mutations in hepatocyte nuclear factor-1-beta cause the "renal cysts and diabetes syndrome," isolated renal cystic dysplasia, and a variety of other malformations. Based on its expression pattern and the observation of two affected cases, we propose that haploinsufficiency of hepatocyte nuclear factor-1-beta may be causally related to the production of the prune belly syndrome phenotype through a mechanism of prostatic and ureteral hypoplasia that results in severe obstructive uropathy with urinary tract and abdominal distension.

Familial recurrence of urethral stenosis/atresia.

BACKGROUND: We report the familial recurrence of urethral stenosis/atresia in two sibling fetuses with bladder outlet obstruction, severe oligohydramnios, and pulmonary hypoplasia. Urethral obstruction in the fetus, when severe, results in a dilated urinary bladder (megacystis) and associated urinary anomalies (hydroureter, hydronephrosis, renal dysplasia). Distention of the fetal abdomen, the result of megacystis or urinary ascites, leads to stretching and eventually hypoplasia or even absence of abdominal muscles. CASES: This constellation of findings, known by a variety of terms including "prune belly" syndrome, is associated with a variety of urethral changes, including posterior urethral valves and urethral stenosis/atresia. One fetus manifested unilateral postaxial polydactyly of the left hand. CONCLUSIONS: A microdeletion of 6p25.3, identified in mother and one fetus, is not associated with a gene known to be involved in urethral development and therefore of unknown significance.

Prune belly anomaly on prenatal ultrasound as a presenting feature of ectrodactyly-ectodermal dysplasia-clefting syndrome (EEC).

We report on a fetus with prune belly anomaly presenting at 16 weeks gestation. Clinical evaluation after birth revealed other malformations reminiscent of the EEC syndrome. This diagnosis was also suspected in the mother and finally confirmed in both relatives by identification of a heterozygous mutation (p.R204W) in the p63 gene. With this paper we confirm the previously reported occurrence of prune belly anomaly in the EEC syndrome, however here in this family proven by genetic analysis.