Concordant prune belly syndrome in monozygotic twins

Prune-belly syndrome in Africa: An analysis and systematic review of cases, etiology, treatment, and outcomes

Background:

Prune-belly syndrome is a rare congenital disorder characterized by a spectrum of three anomalies: bilateral undescended testes, dilated urinary tract, and anterior abdominal muscle deficiency.

Objectives:

In developing countries, inadequate access to health care may affect treatment and outcomes of prune-belly syndrome. This study’s goal was to review the anatomical features, etiology, genetics, management, and outcomes of cases in Africa.

Methods:

PubMed was searched to identify case reports and case studies describing prune-belly syndrome in Africa. Data collected from each study included the number of cases, age at diagnosis, sex, description of the abdominal muscles, testes, and urinary tract, as well as associated anomalies, management, and long-term outcomes.

Results:

A total of 16 publications that reported 58 cases in African countries were included. The prevalence of female patients (15.5%) was higher than in developed countries (3%). The abdominal muscles were deficient in all cases, and bilateral cryptorchidism was present in nearly all males (96%). Distension of the bladder was common, with normal anatomy reported in only one case. Bilateral hydroureters and hydronephrosis also were present in the majority of cases. Only six cases (10.3%) had no associated anomalies, such as musculoskeletal or cardiovascular. Karyotyping was performed in only three cases (5.2%) because of limited hospital facilities. Six parents (10.3%) declined treatment for their children, 12 cases (20.7%) were managed conservatively, and 25 (43.1%) received surgical intervention. Patients’ mortality rate was higher than in developed countries.

Conclusion:

Diagnosis and treatment of prune-belly syndrome remains a challenge in Africa, in which multiple factors, such as access to health care and cultural beliefs, affect mortality rates and outcomes. Patient education and support groups may improve compliance with treatment.

Level of evidence:

Not applicable for this multicenter audit.

A rare case report of prune belly syndrome with malnutrition

Prune belly syndrome (PBS) is a rare congenital malformation of unknown etiology characterized by a triad of deficient abdominal wall musculature, undescended testicles and urinary tract malformations. Most of the patients have pulmonary, cardiac, skeletal and gastrointestinal tract anomalies. Lack of abdominal muscles leads to constipation due to inability to perform Valsalva maneuver, which helps push the stool out of the rectum during the defecation. Additionally, frequent respiratory tract infections, persisting constipation and urinary tract infections lead to the development of malnutrition in children. We report this case to raise the awareness of low socioeconomic and low-resource medical settings that malnutrition could be existed or caused by PBS. We also encourage the expansion of pediatric surgery and family medicine training to increase the number of specialist (family medicine) to report and refer PBS in earlier phase, while working in rural areas and remote provinces.

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 β-integrin 1 (ITGβ1).

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.

Prune belly syndrome: current perspectives

Prune belly syndrome (PBS) is a rare but morbid congenital disease, classically defined by a triad of cardinal features that includes cryptorchidism, urinary tract dilation and laxity of the abdominal wall musculature. Children often require numerous surgical interventions including bilateral orchidopexy as well as individually tailored urinary tract and abdominal wall reconstruction. Along with the classic features, patients with PBS often experience gastrointestinal, orthopedic, and cardiopulmonary comorbidities.

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.

Prune belly syndrome

The majority of paediatric surgeons will encounter a patient with prune belly syndrome (PBS) only a few times in their clinical practice. There have been many opposing views in the literature regarding the pathogenesis and management of this complex condition. A detailed review was conducted using PubMed to identify key publications involving PBS. This article discusses the evolution of our understanding of the pathogenesis and diagnosis of PBS, including its typical characteristics. We describe the management options available for bilateral intra-abdominal testes, the deficient abdominal wall, the dilated urinary system and examine the evidence base used to support the current approaches employed.

Genetic basis of prune belly syndrome: screening for HNF1β 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 HNF1β 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 HNF1β mutations. We assessed the role of HNF1β 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 HNF1β gene, and compared to control databases. We performed functional assay testing of the ability of mutant HNF1β to activate a luciferase construct with an HNF1β DNA binding site.

RESULTS

From 32 prune belly syndrome probands (30 males, 2 females) HNF1β 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 HNF1β, suggesting the V61G substitution does not disturb HNF1β function.

CONCLUSIONS

One genomic HNF1β mutation was detected in 3% of patients with prune belly syndrome but found to be functionally normal. Thus, functionally significant HNF1β mutations are uncommon in prune belly syndrome, despite case reports of HNF1β 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.

Fetal megacystis: differential diagnosis

The purpose of our retrospective observational series was to determine whether the sonographic characteristics of fetal megacystic bladders can be used to reliably establish the most likely diagnosis in fetuses with this condition. The sonographic records of pregnant patients referred to our institutions over a 10-year period who were found on initial 2-dimensional sonography to be carrying fetuses with megacystis were examined for evidence of a keyhole sign, bladder thickness, amniotic fluid index, and fetal sex. When available, 3-/4-dimensional sonography, Doppler angiography, tomographic ultrasound imaging, virtual organ computer-aided analysis, and automatic volume calculation were used as part of the detailed fetal anatomic survey. Twenty fetuses with megacystis were identified. Seventeen were male; 2 were female; and 1 had ambiguous genitalia. All male fetuses with megacystis originally had a diagnosis of prune belly syndrome. The diagnosis for 10 male fetuses with a keyhole sign was changed to megacystis secondary to posterior urethral valves. The fetus with ambiguous genitalia had prune belly syndrome. One of the female fetuses had a diagnosis of urethral atresia, and the diagnosis for the other female fetus was megacystis-microcolon-intestinal hypoperistalsis syndrome. In conclusion, in fetuses with megacystic bladders, it is possible to distinguish between cases with prune belly syndrome, posterior urethral valves, urethral atresia, and megacystis-microcolon-intestinal hypoperistalsis syndrome by a detailed anatomic survey using 2- and 3-/4-dimensioinal sonographic techniques.

DNA hypomethylation, transient neonatal diabetes, and prune belly sequence in one of two identical twins

One known genetic mechanism for transient neonatal diabetes is loss of methylation at 6q24. The etiology of prune belly sequence is unknown but a genetic defect, affecting the mesoderm from which the triad abdominal muscle hypoplasia, urinary tract abnormalities, and cryptorchidism develop, has been suggested. We investigated a family, including one twin, with transient neonatal diabetes and prune belly sequence. Autoantibody tests excluded type 1 diabetes. Microsatellite marker analysis confirmed the twins being monozygotic. We identified no mutations in ZFP57, KCNJ11, ABCC8, GCK, HNF1A, HNF1B, HNF3B, IPF1, PAX4, or ZIC3. The proband had loss of methylation at the 6q24 locus TNDM and also at the loci IGF2R, DIRAS3, and PEG1, while the other family members, including the healthy monozygotic twin, had normal findings. The loss of methylation on chromosome 6q24 and elsewhere may indicate a generalized maternal hypomethylation syndrome, which accounts for both transient neonatal diabetes and prune belly sequence.

Hepatic artery aneurysm associated with prune belly syndrome: a case report and review of the literature

Potentially life threatening when they rupture, hepatic artery aneurysms (HAAs) are uncommon and diagnosed at the fifth to sixth decade of life. HAAs are the second most common splanchnic aneurysms after the ones that involve the splenic artery and are more predominant in men than in women with a ratio of 3 to 2. Usually, HAAs are associated with inflammation or traumas to the arteries of the liver. Among the former group, atherosclerosis, arthritis, and collagen vascular disease are the most common, whereas liver biopsy or other radiologic interventions (ie, percutaneous abscess drainage) are frequent iatrogenic causes. HAAs are discovered incidentally in most cases, but some patients can present with intraperitoneal bleeding and hypovolemic shock. The etiology of prune belly syndrome (PBS) is poorly understood, but new evidence suggests that it is caused by mesodermal delay during the fetal development because of an intrauterine injury. We present a case of HAA in a young individual affected by PBS. To our knowledge, this report is the first to describe the existence of these 2 rare conditions in a single patient. We hypothesize that the mesodermal abnormality that involves PBS might be a rare cause of HAA.

Prune belly syndrome. A focused physical assessment

Prune belly syndrome, a rare congenital anomaly, exists almost exclusively in males and consists of genital and urinary abnormalities with partial or complete absence of abdominal wall musculature. The syndrome, caused by urethral obstruction early in development, is the result of massive bladder distention and urinary ascites, leading to degeneration of the abdominal wall musculature and failure of testicular descent. The impaired elimination of urine from the bladder leads to oligohydramnios, pulmonary hypoplasia, and Potter's facies. The syndrome has a broad spectrum of affected anatomy with different levels of severity. The exact etiology of prune belly syndrome is unknown, although several embryologic theories attempt to explain the anomaly. With advances in prenatal screening techniques, the diagnosis and possible treatment of prune belly syndrome can occur before birth, although controversy exists on the proper management of prune belly syndrome. This article explores the theories behind the pathophysiology and embryology of prune belly syndrome and its multisystemic effects on the newborn infant. Specific attention is paid to presentation, clinical features, head-to-toe physical assessment, family support, and nursing care of infants with prune belly syndrome.

Evaluating the association between congenital cystic adenomatoid malformation of the lung and abdominal wall laxity

We report a male fetus with congenital cystic adenomatoid malformation of the lung, who was treated by laser with resolution of hydrops. Postnatally, the infant had the typical abdominal wall laxity and undescended testes characteristic of prune-belly syndrome. The sonographic diagnosis of cystic adenomatoid malformation was confirmed histologically after postnatal resection. The relationship between cystic adenomatoid malformation and prune-belly syndrome is evaluated through analysis of the present and previously reported cases. We show that there does appear to be a true association between cystic adenomatoid malformation and prune-belly syndrome. We also, however, demonstrate that the traditional explanation (cystic adenomatoid malformation-related hydrops causes ascitic abdominal distension resulting in prune-belly syndrome) is unlikely to be straightforwardly correct.

Patterns of inheritance in familial prune belly syndrome

We present a case of familial prune belly syndrome and review potential modes of inheritance for the syndrome. A total of 11 cases of familial prune belly syndrome have been reported. These cases were reviewed and possible modes of inheritance were determined for each case. Our review strongly suggests a sex-influenced autosomal recessive mode of inheritance.

Vertically transmitted hypoplasia of the abdominal wall musculature

The prune belly syndrome (OMIM 100100) is an association of bladder dilation with hypoplasia of the abdominal wall muscles. This malformation sequence is due to early urethral obstruction. We report a family with abdominal wall muscular hypoplasia as an isolated defect, not associated with the urethral obstruction sequence. The proband is a q3-year-old male who presented with abdominal wall laxity and severe constipation. His mother, maternal grandmother and younger brother had varying degrees of abdominal wall muscular deficiency and constipation. His mother's condition was aggravated by her 2 pregnancies. This family shows vertical transmission (compatible with autosomal dominant or mitochondrial inheritance) of the abdominal phenotype of prune belly sequence without any evidence of urinary tract or renal pathology. The expression in the sons may remain incomplete because abdominal distention due to pregnancy will not occur.