Non-VACTERL-type anomalies are frequent in patients with esophageal atresia/tracheo-esophageal fistula and full or partial VACTERL association

INTRODUCTION

Quan and Smith in 1973 introduced the acronym VATER for a sporadic constellation of birth defects that occur together in the same infant more often than by chance alone (Quan and Smith, 1973). VATER stands for Vertebral defects, Anal atresia, Tracheo-Esophageal fistula (TEF) and/or esophageal atresia (EA), Renal anomalies, and Radial dysplasia. Later, cardiac (C) and limb (L) defects were added and the acronym was extended to VACTERL (Nora and Nora, 1975). The inclusion of cardiac defects is still debated, however, as is the number of defects needed for the diagnosis of a VACTERL association (Botto et al., 1997; Czeizel and Ludanyi, 1985; Czeizel et al., 1988; Kallen et al., 2001; Khoury et al., 1983; Martinez-Frias and Frias, 1999; Rittler et al., 1996). Reported prevalences of a full or partial VACTERL association range from 0.3 to 2.1 per 10,000 live births, depending on the clinical definition used and the population studied (Botto et al., 1997; Khoury et al., 1983; Rittler et al., 1996).

Other defects, such as cleft lip and/or palate and urogenital anomalies occur more frequently than expected in conjunction with the VACTERL association, but are usually not considered to be part of it (Botto et al., 1997; Czeizel et al., 1988; Khoury et al., 1983; Weaver et al., 1986).

The etiology of the VACTERL association is still unclear and is considered to be multifactorial. A few specific chromosomal anomalies, such as distal 13q deletions and 17q deletions, have been described in patients displaying characteristics of the VACTERL spectrum, but no single chromosomal defect has been shown to play an etiologic role (Dallapiccola et al., 1993; Marsh et al., 2000; Park et al., 1992; Shaw-Smith et al., 2005).

Sonic hedgehog (shh) knockout mice show defects comparable to the VACTERL phenotype. However, anomalies of SHH have not specifically been associated with the VACTERL association in humans (Schinzel, 2001).

Environmental exposures during pregnancy, such as exogenous sex hormones during the first trimester of pregnancy, have been suggested as risk factors (Nora and Nora, 1975); however no single environmental risk factor has consistently been identified (Czeizel and Ludanyi, 1985; Lammer and Cordero, 1986; Rittler et al., 1997; Wilson and Brent, 1981).

When Adriamycin, an antibiotic used in chemotherapy, is given to pregnant rats, it produces many anomalies of the VACTERL-type in the offspring (Diez-Pardo et al., 1996). So far, however, the association of Adriamycin or structurally related substances with VACTERL-type anomalies has not been observed in humans (Germann et al., 2004; Hassenstein and Riedel, 1978; Matalon et al., 2004).

The reported proportions of patients with the full or partial VACTERL spectrum of defects that includes EA/TEF range from 24 to 67% (Botto et al., 1997; Czeizel et al., 1988; Khoury et al., 1983; Weaver et al., 1986). However, only five articles describe this specific group of patients (Chittmittrapap et al., 1989; Czeizel et al., 1988; Keckler et al., 2007; Temtamy and Miller, 1974; Torfs et al., 1995). Previous studies either describe a small sample of cases (Chittmittrapap et al., 1989; Temtamy and Miller, 1974), or do not describe non-VACTERL-type defects (Torfs et al., 1995), or use a wide definition of VACTERL association (Keckler et al., 2007).

In this study, we evaluated a large sample of patients with EA/TEF for the occurrence of defects of the VACTERL spectrum and for additional non-VACTERL-type structural malformations in particular. Our rationale was to give a detailed description of all anomalies present in these patients, who may share a common, but so far unknown, etiology (Martinez-Frias et al., 1998).

METHODS

We evaluated data stored in the databases of the Erasmus MC-Sophia Children's Hospital in Rotterdam and the Pediatric Surgical Center of Amsterdam (Emma Children's Hospital AMC and VU University Medical Center), both in the Netherlands. The pediatric surgical departments of these university hospitals are among the six tertiary referral centers for pediatric surgery in the Netherlands. All children born with EA/TEF in the Netherlands are treated in one of these six centers. The Sophia Children's Hospital is the pediatric referral center for the Southwestern part of the Netherlands and has the only specialized pediatric surgical intensive care unit in the Netherlands. The Pediatric Surgical Center of Amsterdam is the referral center for pediatric surgical patients in the Northwestern provinces. Together, these hospitals cover almost half of the population of the Netherlands and around 70,000 births annually. All infants with EA/TEF born in the referral areas are admitted to either of the two hospitals. Both centers keep comprehensive databases on cases with EA/TEF, including data on associated anomalies, pregnancy history, and postnatal clinical course.

As a criterion for the diagnosis of the VACTERL association, we used the presence of EA/TEF and at least two additional defects of the VACTERL-spectrum, namely, vertebral anomalies (including rib anomalies), anal atresia, cardiovascular malformations, renal anomalies, or radial type limb anomalies.

Karyotyping by G-banding with a resolution of at least 550 bands was performed in patients on clinical grounds as decided by the treating physicians. If a patient died, consent to perform autopsy was asked and autopsy was performed if the parents consented.

After approval from the medical ethics review boards of both hospitals, the databases were searched for patients born between January 1988 and August 2006 inclusive, who fulfilled these criteria. Cases with known syndromes and chromosomal anomalies were excluded from the analysis.

Medical records from all patients whose defects fulfilled the criteria were checked for the presence of associated non-VACTERL-type anomalies. Undescended testis was not classified as a congenital anomaly in infants who were born preterm. Data were analyzed using SPSS 12.0.1.

RESULTS

A total of 463 patients with EA and/or TEF were admitted to either of the two centers from January 1988 to August 2006. Of these, 107 (23.1%) patients had two or more additional VACTERL-type defects. Seventeen patients with a recognized etiology, such as a syndrome or a chromosomal disorder, were excluded (Table 1). Of the 17 excluded patients, 13 had chromosomal aberrations, one had a gene mutation, and three had a syndrome without (known) chromosomal or genetic aberrations. This left 90 (19.4%) cases for analysis, which included 58 (64.4%) males and 32 (35.6%) females. Using the Gross classification, we identified four (4.4%) cases with type A (isolated EA), one case (1.1%) with type B (EA with proximal TEF), 81 (90.0%) with type C (EA with distal TEF), two cases (2.2%) with type D (EA with proximal and distal TEF), and one (1.1%) case with TEF without EA (type E) (Gross, 1953). One patient with type C had two distal fistulas. The type was not recorded in one patient.

Gestational ages ranged from 26 4/7 to 42 3/7 weeks (median 37 4/7 weeks). Thirty-five cases (38.9%) were born preterm (<37 weeks) and six cases (6.7%) were post-term (42 weeks or more). Birth weights ranged from 775 to 3,825 g (mean 2,420 g). Twenty-five cases (27.8%) were small for gestational age (more than two standard deviations below the mean). Gestational age and birth weight data were missing for one patient.

A total of 25 patients (27.8%) died, of whom 13 (52.0%) were at a neonatal age (median age of death 4 days, range 0–21 days) and 11 (44.0%) were at an infant age (median age of death 142 days, range 40–1,971 days). For one child, there was no information on age at death.

Exact causes of death are not recorded in the databases. One of the 25 cases who died had all six anomalies of the VACTERL spectrum (full VACTERL association), three had five anomalies, five had four anomalies, and 16 had three. Twenty-two cases had a cardiac defect, of whom six had more than one cardiac defect. Four patients had severe anomalies of the respiratory tract, including one case with tracheal agenesis, and three had CNS anomalies, one of them a myelomeningocele. Of course, these anomalies are not mutually exclusive and the combination of defects likely contributed to the death of those children, taking into account withdrawal of treatment in selected cases. Autopsy was performed on 10 (40%) of the patients who died. This did not reveal new congenital anomalies.

Karyotyping was performed for 67 (74.4%) cases. As children with chromosomal anomalies were excluded from the analysis (see Table 1), all 67 children that were examined had a normal karyotype.

One of our patients had an older brother with isolated EA/TEF.

Table 2 gives an overview of the VACTERL-type defects other than EA/TEF found in the 90 studied cases. The vertebrae/ribs and the cardiovascular system were most commonly affected (68.9 and 65.6%, respectively). Of the 90 cases, 59 (65.6%) had three defects, 22 (24.4%) had four defects, seven (7.8%) had five defects, and two (2.2%) patients (both girls) were diagnosed with all six VACTERL components.

Interestingly, while only 27 cases (30.0%) had only VACTERL-type defects, as many as 63 cases (70.0%) had VACTERL-type defects in association with other structural defects (Table 3). A high occurrence of a single umbilical artery (20.0%) and of genital defects (23.3%) was observed. There was only one preterm infant with undescended testis and without other genital anomalies, so this child was not included in the “genital” group. Other associated defects included respiratory tract anomalies (13.3%), duodenal atresia (8.9%), and cleft lip/jaw/palate (4.4%).

DISCUSSION

This study, based on data from Pediatric Surgical Centers, describes a group of 90 patients with both EA/TEF and at least two other defects included in the VACTERL spectrum. The defects are well documented, thanks to the routine screening of children with EA/TEF for VACTERL-type defects by more detailed, mainly noninvasive, diagnostic techniques (e.g., renal and cardiac ultrasound) since the late 1980s. All patients in our study were screened for other VACTERL-type defects by X-rays of the vertebrae and ribs, and by cardiac and renal ultrasound. Further imaging techniques were only done on clinical grounds and were not part of the standard screening.

The most remarkable finding in our population was that as many as 70% of all patients showed defects other than those included in the VACTERL association. The corresponding figures reported by other authors are often much lower, with a maximum of 57%, reported by Czeizel et al. (Chittmittrapap et al., 1989; Czeizel et al., 1988).

In a study of the VACTERL association that included all cases with any three or more of the six defects, but not necessarily EA/TEF, non-VACTERL-type anomalies were described in 20% (Khoury et al., 1983). The high numbers reported in our population may reflect the high percentage of patients with EA/TEF that have associated anomalies in general (around 50%) (Chittmittrapap et al., 1989; Depaepe et al., 1993). In addition, our population of cases is very well documented, as many cases were also assessed by a clinical geneticist/dysmorphologist, thus increasing the likelihood of reporting minor anomalies. However, most observed non-VACTERL-type defects were not minor anomalies that would be missed on routine clinical examination.

Comparing our results to those of others is not an easy task. Several of the defects associated with EA/TEF are also associated in the absence of EA/TEF (Kallen et al., 2001; Khoury et al., 1983; Rittler et al., 1996). However, we focused on defects associated with EA/TEF and only describe those patients with EA/TEF and at least two other VACTERL-type defects, according to our definition of full or partial VACTERL association. There are only a few articles in the literature reporting data from populations similar to ours (Chittmittrapap et al., 1989; Czeizel et al., 1988; Keckler et al., 2007; Temtamy and Miller, 1974; Torfs et al., 1995).

In a study that focused on 1,846 infants with anorectal defects, Cuschieri et al. found 181 cases that also had one or more of the VACTERL-associated type of defects. Fifty-seven of these also had EA/TEF, showing the association of these two types of defects from the perspective of anorectal defects (Cuschieri, 2002). Our study parallels theirs, but starts with a population of infants with EA/TEF instead of anorectal defects.

In our population, 20% of cases had a single umbilical artery (SUA). The corresponding figure reported by Chittmittrapap et al. (1989) was 8%, but Temtamy and Miller (1974), in a smaller group, described an incidence of 70%. In a study based on data for 292 cases of EA/TEF in the United States, Torfs et al. (1995) reported a strong association between SUA and EA/TEF in general, with SUA found in 18.2% of cases. This population, however, included 36 cases with aneuploidies and syndromes. Nevertheless, none of the 28 trisomy cases had a SUA (Torfs et al., 1995) and exclusion of these cases would therefore bring up this proportion to 20%, which is similar to our finding.

We found duodenal atresia in 8.9% of our population, and cleft lip, jaw, and/or palate in 4.4%. One of the two other studies with data comparable to ours reports duodenal atresia in a similar proportion of cases (8.0%), but does not report cases of clefts (Chittmittrapap et al., 1989). The other comparable study, that by Czeizel et al. (1988), found cleft lip and/or palate in 13.2% and intestinal atresia (n.o.s.) in 2.6%. In studies of associated anomalies in children with EA/TEF, cleft lip and palate were reported in 2.6 and 2.7% of patients (Deurloo and Aronson, 2003; Spitz et al., 2003). Keckler et al. (2007) recently described cleft palate in 4.5% and cleft lip in 0.9% of cases. These latter numbers are very similar to ours, yet the population is somewhat different (Keckler et al., 2007).

In our study, anomalies of the respiratory system were present in 13% of cases. This finding is not entirely surprising, as both the esophagus and the respiratory system develop from the foregut. The presence of EA/TEF may be a sign of defective foregut development in general, which could also lead to respiratory tract anomalies. A number of mouse knockout models that show EA/TEF also display anomalies of the respiratory system, for example, knockout mice for either shh, gli2/gli3, or Ttf-1 (Litingtung et al., 1998; Minoo et al., 1999; Motoyama et al., 1998). In a group of 25 cases with EA/TEF and at least two other defects of the VACTERL-spectrum, Chittmittrapap et al. (1989) described the absence of the right upper lobe of the lung in one patient (4%). Temtamy and Miller (1974) reported the occurrence of unilateral lung agenesis in an unspecified number of cases among a similar, but smaller, group of 10 cases of EA/TEF combined with at least two other VACTERL-type defects. Czeizel et al. (1988) found lung hypoplasia/agenesis in 7.9% of their population of patients with EA/TEF and at least two other anomalies of the VACTERL-spectrum.

We observed that 19.4% of 463 infants with EA/TEF had at least two additional defects of the VACTERL-spectrum, a proportion that falls in the range of prevalences (10–32%) reported by others (Chittmittrapap et al., 1989; Temtamy and Miller, 1974; Tönz et al., 2004; Torfs et al., 1995). We found 64.4% of all these cases to be boys, which compares with proportions reported earlier (Chittmittrapap et al., 1989; Czeizel et al., 1988).

Only a small proportion of patients had the whole spectrum of six anomalies, thereby representing the “full” VACTERL association. Although several studies on the VACTERL association include patients with only two of the anomalies of the VACTERL spectrum (Rittler et al., 1996, 1997; Weaver et al., 1986), most studies include only patients with three or more of the defects (Botto et al., 1997; Chittmittrapap et al., 1989; Czeizel and Ludanyi, 1985; Czeizel et al., 1988; Kallen et al., 2001; Temtamy and Miller, 1974). We have adopted the latter, more stringent definition with the restriction that EA/TEF always be included.

Therefore, most patients in our study have a “partial” VACTERL association. Our data do not permit us to draw conclusions about the number of defects, nor which defects of the spectrum must necessarily be included for the term “VACTERL” to apply. Also, some studies exclude patients who fulfill the criteria for VACTERL association, but who have been diagnosed with a specific chromosomal anomaly or syndrome (Khoury et al., 1983; Weaver et al., 1986). The same decision was made in the present study. However, others have included such cases, which makes comparison between studies more difficult (Keckler et al., 2007).

In many centers, karyotyping is now standard practice for children with multiple congenital anomalies or even for all children with one or more major congenital anomalies. In addition, more sophisticated cytogenetic techniques have made it possible to detect smaller chromosomal anomalies that may have gone undetected in earlier days. Therefore, studies that excluded children with major chromosomal anomalies may unknowingly have included children with chromosomal anomalies that less sensitive techniques could not detect. In the future, it might be indicated to re-examine those children who were diagnosed earlier as having a normal karyotype, both clinically by a clinical geneticist, as well as by using more detailed techniques, such as array-based Comparative Genomic Hybridization (Pinkel et al., 1998). This approach has been successfully implemented in other major congenital anomalies, such as congenital diaphragmatic hernia (Scott et al., 2007).

In summary, this study describes phenotypes of patients with EA/TEF and full or partial VACTERL association treated in two large pediatric surgical centers. Their clinical data are well-documented in comprehensive databases. Importantly, this study shows that 70% of patients display non-VACTERL-type congenital anomalies in addition to defects of the VACTERL spectrum. We believe this study gives a good overview of the spectrum of anomalies seen in these patients and that it adds to the knowledge of the clinical characteristics displayed by these patients.