Frontonasal malformation and cloacal exstrophy: a previously unreported association

CNV analysis in 169 patients with bladder exstrophy-epispadias complex

Background

The bladder exstrophy-epispadias complex (BEEC) represents the severe end of the congenital uro-rectal malformation spectrum. Initial studies have implicated rare copy number variations (CNVs), including recurrent duplications of chromosomal region 22q11.21, in BEEC etiology.

Methods

To detect further CNVs, array analysis was performed in 169 BEEC patients. Prior to inclusion, 22q11.21 duplications were excluded using multiplex ligation-dependent probe amplification.

Results

Following the application of stringent filter criteria, seven rare CNVs were identified: n = 4, not present in 1307 in-house controls; n = 3, frequency of <0.002 in controls. These CNVs ranged from 1 to 6.08 Mb in size. To identify smaller CNVs, relaxed filter criteria used in the detection of previously reported BEEC associated chromosomal regions were applied. This resulted in the identification of six additional rare CNVs: n = 4, not present in 1307 in-house controls; n = 2, frequency <0.0008 in controls. These CNVs ranged from 0.03–0.08 Mb in size. For 10 of these 13 CNVs, confirmation and segregation analyses were performed (5 of maternal origin; 5 of paternal origin). Interestingly, one female with classic bladder extrophy carried a 1.18 Mb duplication of 22q11.1, a chromosomal region that is associated with cat eye syndrome.

Conclusions

A number of rare CNVs were identified in BEEC patients, and these represent candidates for further evaluation. Rare inherited CNVs may constitute modifiers of, or contributors to, multifactorial BEEC phenotypes.

Cloacal exstrophy with extensive Chiari II malformation: case report and review of the literature

INTRODUCTION

Cloacal exstrophy is a rare condition characterized by a defect in the abdominal wall with extrusion of malformed abdominal contents. The normal separation of the genitourinary and gastrointestinal systems does not occur. While patients with cloacal exstrophy have a high incidence of spinal defects, cranial defects are rare. Chiari malformation has been rarely reported in children with cloacal exstrophy, although the embryogenesis is unknown.

OBJECTIVE

In this report, the authors describe a child with cloacal exstrophy and a large myelocystocele. The child also had an extensive Chiari II malformation.

RESULTS

We review the relevant embryology and suggest a possible mechanism for Chiari formation in this patient.

Bladder exstrophy: an epidemiologic study from the International Clearinghouse for Birth Defects Surveillance and Research, and an overview of the literature

Bladder exstrophy (BE) is a complex congenital anomaly characterized by a defect in the closure of the lower abdominal wall and bladder. We aimed to provide an overview of the literature and conduct an epidemiologic study to describe the prevalence, and maternal and case characteristics of BE. We used data from 22 participating member programs of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR). All cases were reviewed and classified as isolated, syndrome, and multiple congenital anomalies. We estimated the total prevalence of BE and calculated the frequency and odds ratios for various maternal and case characteristics. A total of 546 cases with BE were identified among 26,355,094 births. The total prevalence of BE was 2.07 per 100,000 births (95% CI: 1.90-2.25) and varied between 0.52 and 4.63 among surveillance programs participating in the study. BE was nearly twice as common among male as among female cases. The proportion of isolated cases was 71%. Prevalence appeared to increase with increasing categories of maternal age, particularly among isolated cases. The total prevalence of BE showed some variations by geographical region, which is most likely attributable to differences in registration of cases. The higher total prevalence among male cases and older mothers, especially among isolated cases, warrants further attention.

The exstrophy-epispadias complex

Exstrophy-epispadias complex (EEC) represents a spectrum of genitourinary malformations ranging in severity from epispadias (E) to classical bladder exstrophy (CEB) and exstrophy of the cloaca (EC). Depending on severity, EEC may involve the urinary system, musculoskeletal system, pelvis, pelvic floor, abdominal wall, genitalia, and sometimes the spine and anus. Prevalence at birth for the whole spectrum is reported at 1/10,000, ranging from 1/30,000 for CEB to 1/200,000 for EC, with an overall greater proportion of affected males. EEC is characterized by a visible defect of the lower abdominal wall, either with an evaginated bladder plate (CEB), or with an open urethral plate in males or a cleft in females (E). In CE, two exstrophied hemibladders, as well as omphalocele, an imperforate anus and spinal defects, can be seen after birth. EEC results from mechanical disruption or enlargement of the cloacal membrane; the timing of the rupture determines the severity of the malformation. The underlying cause remains unknown: both genetic and environmental factors are likely to play a role in the etiology of EEC. Diagnosis at birth is made on the basis of the clinical presentation but EEC may be detected prenatally by ultrasound from repeated non-visualization of a normally filled fetal bladder. Counseling should be provided to parents but, due to a favorable outcome, termination of the pregnancy is no longer recommended. Management is primarily surgical, with the main aims of obtaining secure abdominal wall closure, achieving urinary continence with preservation of renal function, and, finally, adequate cosmetic and functional genital reconstruction. Several methods for bladder reconstruction with creation of an outlet resistance during the newborn period are favored worldwide. Removal of the bladder template with complete urinary diversion to a rectal reservoir can be an alternative. After reconstructive surgery of the bladder, continence rates of about 80% are expected during childhood. Additional surgery might be needed to optimize bladder storage and emptying function. In cases of final reconstruction failure, urinary diversion should be undertaken. In puberty, genital and reproductive function are important issues. Psychosocial and psychosexual outcome depend on long-term multidisciplinary care to facilitate an adequate quality of life.

Genetische und molekularbiologische Aspekte des Blasenekstrophie-Epispadie-Komplexes (BEEK)

The bladder exstrophy and epispadias complex (BEEC) is an anterior midline defect with variable expression involving the infraumbilical abdominal wall including the pelvis, urinary tract, and external genitalia. The incidence varies with regard to ethnical background, sex, and phenotypic expression, and an incidence of 1:20,000 to 1:80,000 has been observed in the middle European population. No gene defect has been attributed to BEEC thus far and chromosomal aberrations or genetic syndromes associated with BEEC have only rarely been reported. According to epidemiological data, a complex genetic as well as a multifactorial mode of inheritance could underlie BEEC. However, no single teratogenic agent or environmental factor has been identified, which could play a dominant role in the expression of the BEEC.A risk of recurrence of 0.5-3% has been described in families with one affected subject. These values correspond to an increased recurrence risk estimated to be as high as 200- to 800-fold when compared to the common population. Due to the paucity of affected sib pairs and suitable multiplex families, conventional linkage analysis to identify candidate genes causally related with BEEC appears to be unfeasible. Large association studies and consecutive linkage disequilibrium mapping should therefore lead to the identification of candidate genes. Also new methods including matrix-based comparative genomic hybridization (CGH) are promising and have successfully been used in the past (e.g., CHARGE association). Moreover, the low incidence of the BEEC requires close cooperation between clinicians in the operative and nonoperative specialties as well as geneticists for successful gene search.

The morphogenesis of the exstrophy-epispadias complex: a new concept based on observations made in early embryonic cases of cloacal exstrophy

BACKGROUND

The term exstrophy-epispadias complex (EEC) has been coined for a group of congenital malformations that includes epispadias, bladder exstrophy and cloacal exstrophy. It is usually thought that these malformations develop against a similar embryological background. This background, however, is still obscure. This is mainly due to the lack of availability of abnormal human or non-human embryos showing the crucial developmental steps in the morphogenesis of EEC malformations. In this paper, we present chick embryos that show cloacal exstrophy at early developmental stages. To the best of our knowledge, this is the first documentation of this rare malformation in young embryos.

MATERIALS AND METHODS

Embryos with cloacal exstrophy (n=4) were found among embryos from two experimental series (n=50) that were primarily performed to document the early morphogenesis of facial and cardiovascular malformations. The malformations were induced by the administration of suramin according to established protocols. Suramin can induce a spectrum of malformations including facial clefts, heart defects, and cloacal exstrophy.

RESULTS AND CONCLUSIONS

Besides the presence of an abnormal opening into the cloaca, all embryos were characterised by an abnormal broadening of the caudal trunk at the level of the leg buds, which, in the youngest embryos, was associated with the abnormal presence of large aneurysmatic swellings of the dorsal aortae at this side. We postulate that these aneurysmatic swellings might be the primary defects leading to the development of EEC malformations. These space-occupying anomalies seem to cause abnormal distensions of the developing pelvis and of the infra-umbilical portion of the developing body wall. In consequence, the mid-portion of the developing ventral body wall between the origin of the umbilical cord and the cloacal plate becomes stretched and thinned out. Tension and thinning of the ventral body wall might ultimately lead to its rupture with exposure of the lumen of the embryonic cloaca and allantois. This new concept on the morphogenesis of the EEC is the first not to be inferred from the conditions seen in fetal or postnatal human cases but is based entirely on data from malformed embryos.

Severe lower limb defects in exstrophy of the cloaca

We present here a patient with exstrophy of the cloaca associated with severe lower limb defects. The limb malformations include, on the right, a split foot with distal separation of the tibia and fibula, and on the left, attachment of the lower half of the left leg with a two-toed foot at nearly a right angle to the mid left thigh. A review of the literature indicates that 17-26% of patients with cloacal exstrophy also have lower limb defects. We hypothesize that cloacal exstrophy and associated lower limb defects have a related pathogenesis and that both are related to deficiencies of caudal mesoderm or mesodermal differentiation signals. More cases of exstrophy of the cloaca with limb defects need to be reported to better characterize the limb anomalies and to more precisely determine their frequency.

Chiari I malformation and cloacal exstrophy: report of a patient with both defects of blastogenesis

We report on child with Chiari I malformation (CIM) and cloacal exstrophy, a combination of findings that has not been reported previously. CIM and cloacal exstrophy both demonstrate abnormalities that represent maldevelopment of the midline field. This combination of anomalies in this patient suggests an impairment of midline development during blastogenesis.

Exstrophy of the cloaca and exstrophy of the bladder: two different expressions of a primary developmental field defect

Exstrophy of the bladder (EB) and exstrophy of the cloaca (EC) are generally recognizable as distinct clinical entities. In patients with EB, the posterior bladder wall is exposed through a midline defect of the abdomen. The umbilicus is inferiorly displaced and located close to the superior margin of the exstrophic bladder. Genital abnormalities are common in boys and girls who may present epispadias and a small, split phallus or a split clitoris, a bifid uterus, and a duplicate or exstrophic vagina. In contrast to classic EB, EC is commonly associated with omphalocele, spinal defects, and incompletely formed external genitalia and is always associated with imperforate anus. Some authors state that EC and EB constitute two distinct disorders, but others consider them part of a "continuum," representing different levels of severity within the same spectrum. The use of the acronym OEIS to refer to the combination of omphalocele, exstrophy, imperforate anus, and spinal defects, in our opinion, has not helped to clarify the clinical definition, pathogenesis, or cause of this multiple congenital anomaly (MCA) pattern, mostly because the term makes no distinction between EC or EB. Here we present the epidemiological analysis of a group of characteristics in infants with EC and infants with EB to determine if they constitute two different entities. We also analyze if the different combinations of omphalocele, imperforate anus, and spinal defects are more frequent in infants with EC than in infants with MCA patterns other than EC and EB. The prevalence in our data for EC was 1:200,233 live births and 1:35,597 for EB. The clinical analysis indicated that the study defects (omphalocele, spine defects, spina bifida, and imperforate anus) tend to occur together in the same child with a higher frequency if the child has the EC defect than in infants with MCA patterns that did not include EC or EB. Our findings of low birth weight, twinning, single umbilical artery, and preferentially associated malformations suggest that EC is the result of damage occurring very early in development and that EC and EB are two different expressions of a primary polytopic developmental field defect.