De novo 13q deletions in two patients with mild anorectal malformations as part of VATER/VACTERL and VATER/VACTERL‐like association and analysis of EFNB2 in patients with anorectal malformations

Abstract

Anorectal malformations (ARMs) comprise a broad spectrum of conditions ranging from mild anal anomalies to complex cloacal malformations. In 40-50% of cases, ARM occurs within the context of defined genetic syndromes or complex multiple congenital anomalies, such as VATER/VACTERL (vertebral defects [V], ARMs [A], cardiac defects [C], tracheoesophageal fistula with or without esophageal atresia [TE], renal malformations [R], and limb defects [L]) association. Here, we report the identification of deletions at chromosome 13q using single nucleotide polymorphism-based array analysis in two patients with mild ARM as part of VATER/VACTERL and VATER/VACTERL-like associations. Both deletions overlap the previously defined critical region for ARM. Heterozygous Efnb2 murine knockout models presenting with mild ARM suggest EFNB2 as an excellent candidate gene in this region. Our patients showed a mild ARM phenotype, closely resembling that of the mouse. We performed a comprehensive mutation analysis of the EFNB2 gene in 331 patients with isolated ARM, or ARM as part of VATER/VACTERL or VATER/VACTERL-like associations. However, we did not identify any disease-causing mutations. Given the convincing argument for EFNB2 as a candidate gene for ARM, analyses of larger samples and screening of functionally relevant non-coding regions of EFNB2 are warranted. In conclusion, our report underlines the association of chromosome 13q deletions with ARM, suggesting that routine molecular diagnostic workup should include the search for these deletions. Despite the negative results of our mutation screening, we still consider EFNB2 an excellent candidate gene for contributing to the development of ARM in humans.

Chromosome 13q deletion syndrome involving 13q31-qter: A case report

“…Human embryological studies have demonstrated that the primitive urogenital sinus and anorectal canal originate from the primitive cloaca, and there are number of molecular events that govern the developmental processes underlying cloacal septation, closure of the perineum and scrotum, urethral tubularization and penoscrotal positioning (26–28). The results obtained from patient 1 in the present study, together with those obtained from patients with genitourinary/anorectal anomalies in 13q deletion syndrome from previous studies (3,4,6–8,11,14–18), have identified two critical regions, 13q33.3-qter and 13q22.1–31.3. In recent years, the non-morbid online Mendelian Inheritance in Man (OMIM) gene, ephrin B2 ( EFNB2 ) located in 13q33.3, has been recognized as a strong candidate gene for hypospadias or anorectal anomalies in 13q deletion syndrome in a number of studies (4,7–9,18).…”

“…1 and Table II, and a summary of the regions on chromosome 13 identified in the present and previous studies (3,4,6–8,10,11,14–22) are reviewed in Fig. 2.…”

“…Previous studies have proposed the existence of the following 3 groups of genotype-phenotypes based on the involvement of the critical 13q32 band in the deletion (2,5): i) proximal deletions with a non-deleted 13q32 band are observed primarily in patients with mild mental retardation, growth delay and inconstant retinoblastoma; ii) a 13q32 band deletion is associated with severe congenital malformations; iii) a distal deletion without a 13q32 deletion has been observed in patients with severe mental retardation, no brain malformation or growth delay. Previous studies involving the use of array comparative genomic hybridization (CGH) coupled with fluorescence in situ hybridization, reverse transcription-quantitative polymerase chain reaction (qPCR) and multiple ligation-depended probe amplification to determine the precise breakpoint of the unbalanced chromosomal translocation have been conducted (3–5,7–11). This analysis has provided information regarding the molecular genotype-phenotype in chromosome 13 deletion syndrome.…”

Underlying genetic factors of the VATER/VACTERL association with special emphasis on the “Renal” phenotype

“…These include: (i) deletions of 5q11.2 [25], 6q [26], 7q35-qter [27], distal 13q [28,29], 19p13.3 [30], and 20q13.33 [31]; (ii) duplications on 1q41, 2q37.3, and 8q24.3 [32], 9q [33] and at 22q11.21 [34]; (iii) deletion at Yq with duplication at Yp [35], and deletion of 9p24.3-p24.1 with duplication of 18q12.3-q23 [36]; (iv) supernumerary der(22) syndrome [37]; (v) mosaicism for supernumerary ring chromosome 12 [38] or 18 [39]; and (vi) partial monosomy 16p13.3pter/partial trisomy 16q22qter [40]. The smallest of these microaberrations was identified in the study by Hilger et al [32], describing a de novo microduplication at 2q37.3 with an estimated size of 25kb.…”

PCSK5 mutation in a patient with the VACTERL association

“…The etiology of the VACTERL association is not still fully understood, although HOXD13 , ZIC3 , PTEN , FANCB , FOXF1 , and TRAP1 mutations have been reported as possible contributors to the VACTERL association or the VACTERL-like association as described previously [2–9]. Several microduplications and microdeletions are also reportedly associated with the VACTERL association [10, 11]. However, these findings have had sparsely be replicated.…”