Congenital perineal grove: an unusual Anorectal anomaly in females-report of two cases and literature review.

Congenital perineal grove (CPG) is a rare anorectal anomaly; only 65 cases have been reported in literature. Two cases who were referred for evaluation of a lesion in the perineum are reported here. The patients were diagnosed clinically as CPG in neonatal period and were initially managed conservatively. Surgery was required in one case as the lesion was persistent and symptomatic. A high index of suspicion is required for diagnosis of CPG to avoid parental anxiety and unnecessary diagnostic work-up and surgery. Surgery is required only in cases where the lesion persists or there is infection, pain, and ulceration.

Levator ani asymmetry and deviation in high-type anorectal malformation evaluated by magnetic resonance imaging.

INTRODUCTION: The levator ani (LA) complex in high-type imperforate anus (H-IA), low-type imperforate anus (L-IA), and Hirschsprung's disease (HD) patients as controls were documented using magnetic resonance imaging (MRI) and compared for symmetry. MATERIALS AND METHODS: Mean left:right LA thickness ratio (LA ratio), and deviation of the LA from the pubococcygeal line (PCL; LA angle) were calculated from thin-slice MRI images (axial 2 mm, coronal 2 mm, and sagittal 3 mm) of the puborectalis and pubococcygeus taken parallel to the PCL under sedation in H-IA (n=14), L-IA (n=16), and HD (n=9). RESULTS: MRI scans were performed between January 2018 and June 2021. LA were significantly thinner in H-IA (1.78±0.46 mm) compared with L-IA (2.97±0.55 mm) and controls (2.87±0.32 mm), p<0.0001. LA ratio was significantly lower in H-IA (0.71±0.15) compared with L-IA (0.93±0.04), and controls (0.91±0.06), p<0.0001. Mean LA-angle was significantly different in H-IA, 10.8° (range 6°-19°), versus L-IA and controls, both zero degrees (range 0°-5°), p<0.0001, respectively. CONCLUSIONS: LA was confirmed to be significantly asymmetric in H-IA. Because outcome of surgical repair involving a midline incision, such as posterior sagittal anorectoplasty could be impaired, pediatric surgeons are advised to plan surgical intervention for H-IA carefully and appropriately.

Exome survey of individuals affected by VATER/VACTERL with renal phenotypes identifies phenocopies and novel candidate genes.

The acronym VATER/VACTERL refers to the rare nonrandom association of the following component features (CFs): vertebral defects (V), anorectal malformations (ARM) (A), cardiac anomalies (C), tracheoesophageal fistula with or without esophageal atresia (TE), renal malformations (R), and limb anomalies (L). For the clinical diagnosis, the presence of at least three CFs is required, individuals presenting with only two CFs have been categorized as VATER/VACTERL-like. The majority of VATER/VACTERL individuals displays a renal phenotype. Hitherto, variants in FGF8, FOXF1, HOXD13, LPP, TRAP1, PTEN, and ZIC3 have been associated with the VATER/VACTERL association; however, large-scale re-sequencing could only confirm TRAP1 and ZIC3 as VATER/VACTERL disease genes, both associated with a renal phenotype. In this study, we performed exome sequencing in 21 individuals and their families with a renal VATER/VACTERL or VATER/VACTERL-like phenotype to identify potentially novel genetic causes. Exome analysis identified biallelic and X-chromosomal hemizygous potentially pathogenic variants in six individuals (29%) in B9D1, FREM1, ZNF157, SP8, ACOT9, and TTLL11, respectively. The online tool GeneMatcher revealed another individual with a variant in ZNF157. Our study suggests six biallelic and X-chromosomal hemizygous VATER/VACTERL disease genes implicating all six genes in the expression of human renal malformations.

Upregulation of PPPDE1 contributes to anorectal malformations via the mitochondrial apoptosis pathway during hindgut development in rats.

Congenital anorectal malformations (ARMs) are among the most prominent deformities of the gastrointestinal tract; however, their precise aetiology remains obscure. Immunohistochemistry demonstrated that, in the ARM group, the PPPDE1-positive cells were widely distributed in the hindgut epithelial tissue from GD13 to GD16. Immunofluorescence revealed that most TUNEL-, Bax-, and Cytochrome C (Cyt C)-positive cells overlapped with PPPDE1-positive cells in the urorectal septum (URS). Western blotting and quantitative real-time RT-PCR revealed that PPPDE1 levels were significantly higher in the ARM group from GD13 to GD14 (p < 0.05). IEC-6 cells were transfected with PPPDE1 overexpression plasmid/NC (negative control) or si-PPPDE1/si-NC. Flow cytometry analysis and CCK-8 assay (used to detect apoptosis and proliferation, respectively), as well as western blotting, showed that the levels of PPPDE1 were positively correlated with the pro-apoptotic molecules Bax and Cyt C. Accordingly, aberrantly high expression of PPPDE1 caused a spatiotemporal imbalance in foetal rats with ARMs during hindgut development. Therefore, the upregulation of PPPDE1 may promote epithelial apoptosis and reduce proliferation in the hindgut via the mitochondrial apoptotic pathway. This could affect the fusion of the URS and cloacal membrane, ultimately inhibiting the hindgut development and resulting in ARMs.

Presacral neuroendocrine tumors associated with the Currarino syndrome.

Currarino syndrome (CS) is an autosomal dominant syndrome caused by mutations in MNX1 and characterized by anorectal abnormalities, partial sacral agenesis, and presacral masses. The presacral masses are typically benign; however, malignant degeneration can occur, and presacral neuroendocrine tumors (NETs) have been reported in six cases. We report three individuals from two families affected by CS in which multiple individuals developed presacral NETs. The first family, 491, had six members with features of CS, including two siblings who presented with presacral, Grade 2 NETs, one of which had metastasized to bone and lymph nodes. A germline c.874C>T (p.Arg292Trp) mutation was found in a highly conserved region of MNX1 in three affected members who underwent sequencing. A second somatic variant/deletion in MNX1 was not detected in either patient's tumor. In the second family, 342, the proband presented with an incidentally discovered presacral NET. The proband's father had previously undergone resection of a presacral NET, and so genetic testing was performed, which did not reveal an MNX1 mutation or copy number variants. The lack of a second, somatic mutation in the tumors from family 491 argues against MNX1 acting as a tumor suppressor, and the absence of a germline MNX1 mutation in family 342 suggests that other genetic and anatomic factors contribute to the development of presacral NETs. These cases highlight the variable presentation of CS, and the potential for malignancy in these patients.

[Morphological criteria for surgical treatment of anorectal malformations in children]. / Morfologicheskie kriterii khirurgicheskogo lecheniya anorektal'nykh mal'formatsii u detei.

OBJECTIVE: To improve treatment outcomes in patients with anorectal malformations via research of morphological criteria and differentiated approach to surgical correction. MATERIAL AND METHODS: There were 37 children with various types of anorectal malformations for the period 2000-2019. We analyzed morphological features of atretic rectum wall, fistula, anastomosis with adjacent organs and skin of the perineum. RESULTS: Morphological research of anorectal malformations made it possible to differentiate treatment strategy and explain the causes of unsatisfactory results after perineal and abdominal-perineal proctoplasty. Incidence and severity of complications, as well as early disability were reduced that significantly improved postoperative quality of life. CONCLUSION: According to the morphological criteria, deeper mobilization of atretic rectum within at least 2.5-3 cm of the rectal «cone¼ with intact muscular wall is necessary. This approach was valuable to ensure adequate closure function of the rectum, prevent anal incontinence and restore normal appearance of the perineum. These achievements contributed to decrease in the incidence of admissions, redo surgeries and improvement of social adaptation in children.

Should the search for ganglia in the distal rectal fistula in patients with anorectal malformation be abandoned?

PURPOSE: Occurrence of Hirschsprung's disease in anorectal malformation (ARM) patients is rare, but many surgeons still ask to pathologists to search for ganglia in the terminal rectum/fistula; the histological procedure is time and money consuming and the results confounding. A consecutive series of ARM patients, in which the presence of ganglia in terminal rectum was revised, is herein presented. MATERIALS AND METHODS: Rectal specimens of ARM patients who underwent corrective surgery in the last 6 years were retrieved. The histological protocol included H&E staining and calretinin immunohistochemistry. Each specimen is processed until all material is examined if no ganglia are retrieved after the first twelve sections. RESULTS: Forty cases were examined. Eight patients were younger than 1 month of age at operation. The mean length of the specimen was 1.5cm (range: 1-3 cm). Upon clinical request, ganglia were searched in 15/40 cases (37.5%) and resulted absent in 10/15 (66.5%). All patients have been followed and none developed signs or symptoms suggestive for Hirschsprung. CONCLUSIONS: The practice to search for ganglia in the terminal rectum/fistula in ARM patients should be abandoned, as incidence of associated colorectal diseases is rare. Moreover, the procedure is expensive both in terms of laboratory's reagents and working time of expert pathologists and technicians. LEVEL OF EVIDENCE: Level IV (Case Series with no Comparison Group).

Correlation of anorectal manometry measures to severity of fecal incontinence in patients with anorectal malformations - a cross-sectional study.

Anorectal malformations (ARM) are a spectrum of anomalies of the rectum and anal canal affecting 1 in 2500 to 5000 live births. Functional problems are common and related to the type of ARM and associated malformations. We aimed to evaluate the results of Three-dimensional High Resolution Anorectal Manometry (3D-HRAM) in long-term follow-up after surgical correction of ARM with special reference to fecal incontinence. Twenty-one patients with anorectal malformations and primary repair at our center consented to participate in the study. Pressures of the anal sphincter muscles and defects were addressed by 3D-HRAM. Fecal incontinence and disease-specific quality of life were evaluated by the Fecal Incontinence Quality of Life score and Wexner incontinence score respectively. The study was approved by the Committee in Health Research Ethics and the Danish Data Protection Agency. Median age was 22(12-31) years and 13(67%) participants were females. Sphincter defect was present in 48% (N = 10) of participants. Participants with sphincter defects had significant higher Wexner score and size of sphincter defects and mean anal squeeze pressure were correlated to Wexner score. Participants with or without sphincter defects did not differ on manometry parameters including resting anal and squeeze pressure or disease-specific quality of life. In a study of the long-term outcome after repair of anorectal malformations we found a higher Wexner incontinence score in the presence of an anal sphincter defect and the size of the defect and mean anal squeeze pressure were correlated to the Wexner incontinence score.

Testicular function and sexuality in adult patients with anorectal malformation.

PURPOSE: To collect data on sexual and fertility issues in adult male patients with history of anorectal malformations (ARM). MATERIALS AND METHODS: Thirty adult males born with ARM, cared for at the Pediatric Surgery of Treviso and Padua Hospitals, were enrolled and interviewed about sexual habits and relationships. Testicular ultrasound, evaluation of male sex hormones and semen analysis were performed to assess testicular function and compare data with 15 fertile controls. Presence of erectile dysfunction was evaluated with IIEF-5 questionnaire. RESULTS: Cryptorchidism and recurrent orchiepididymitis were reported in 33% and 40% of patients, respectively. Average testicular volume resulted significantly lower than fertile controls (11.1 vs 14.3 mL, p = 0.002) and 53.5% presented testicular hypotrophy (<10 mL). Erectile dysfunction was reported by a single patient and ejaculatory anomalies by 46.5%. Thirteen patients were azoospermic/cryptozoospermic; 6 of them presented a reduced peripheral sensitivity to androgens (ASI > 139). Coital debut resulted delayed at 18 years old (vs 15 years in the control group). Overall 63.5% reported their condition did not affect their sexual sphere. CONCLUSIONS: Evaluation of testicular function is recommended in ARM patients to detect and treat possible infertility disorders, to recognize the clinical conditions which could affect the spermatogenesis since childhood, and to guarantee psychological support. LEVEL OF EVIDENCE RATING: Prognosis study. Level III (case-control study).

Normal anorectal musculatures and changes in anorectal malformation.

PURPOSE: We investigated the anorectal musclulature in normal children and anorectal malformations (ARM) to evaluate its role in bowel control mechanism. METHODS: Pelves of 50 neonates died of ARM-unrelated diseases and 16 patients with anorectal malformations (8 high, 5 intermediate, and 3 low ARMs) were dissected and analyzed. RESULTS: Normal anorectal musculature was divided into three muscular tubes: the internal sphincter tube (IAST), longitudinal muscle tube (LMT) and transverse muscle tube (TMT). The LMT came from the outer longitudinal smooth muscle fiber of the rectum and the striated muscle fiber of the levator ani, and the TMT composed of the puborectalis and the external anal sphincter. However, in ARM, the IAST was absent and the LMT, the center of the sphincter muscle complex, was only from the levator ani and could be divided into the pelvic portion and the perineal portion. The former, from the upper rim of the puborectalis to the bulbar urethral, became narrowed and dislocated anteriorly near to the posterior urethra in high ARM and rectal pouch in intermediate ARM. The latter, below the bulbar urethra to the anal dimple, was fused to a column both in high and intermediate ARM. The columnar perineal LMT run downwards and then split, penetrated the superficial part of EAS and terminated at the deep aspect of the skin, to form the anal dimple, which represents the center of the perineal LMT from the perineal aspect. The length of the LMT was longer in high and intermediate ARM than the normal neonate. The columnar perineal LMT and narrowed pelvic LMT could be possibly identified by laparoscopic and perineal approaches retrospectively and widened to allow the passage of the rectum through. CONCLUSIONS: The anorectal musculature in ARM is composed of agenesic LMT and TMT and the narrowed LMT gives anatomical evidence of the center, where the neorectum should pull through.

Involvement of proliferative and apoptotic factors in the development of hindgut in rat fetuses with ethylenethiourea-induced anorectal malformations.

BACKGROUND: Anorectal malformations (ARMs) are common congenital malformations of the terminal digestive tract, but little is known regarding their pathogenesis. Aberrant cell proliferation/apoptosis are believed to be involved in ARMs. However, there are no studies on proliferation/apoptosis-related genes. PURPOSE: We aimed to investigate the spatiotemporal expression patterns of two proliferation/apoptosis-related genes (MYC proto-oncogene and tumor protein p53) and explore their potential functions in the hindguts of ethylene thiourea-induced ARMs rat fetuses. METHODS: MYC and p53 expression was evaluated using immunohistochemical staining, western blotting, and quantitative real-time polymerase chain reaction (RT-qPCR). Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and p53 costaining were performed to assay the colocalization of apoptotic and p53-expressing cells. RESULTS: Rat fetuses with ARMs displayed fusion failure of the urogenital septum and cloacal membrane. In the control group, MYC was persistently expressed from gestational day (GD)14 to GD16 and distributed throughout the hindgut, while p53 was weakly detected in the terminal segment of the urethra and hindgut; in the ARMs group, MYC expression was obviously reduced, while p53 was widely and highly expressed in the urethra and hindgut. Western blotting and RT-qPCR confirmed the decrease in MYC and increase in p53 expression in ARMs. TUNEL and p53 co-staining revealed considerable overlap between apoptotic and p53-expressing cells. CONCLUSION: The expression patterns of c-myc and p53 were disrupted in ARMs rat embryos, and the downregulation of c-myc and upregulation of p53 might be related to the development of ARMs at the key time points of ARMs morphogenesis.

Pathogenic copy number variants are detected in a subset of patients with gastrointestinal malformations.

BACKGROUND: Gastrointestinal atresias and urological defects are main causes of pediatric surgery in infants. As copy number variants (CNVs) have been shown to be involved in the development of congenital malformations, the aim of our study was to investigate the presence of CNVs in patients with gastrointestinal and urological malformations as well as the possibility of tissue-specific mosaicism for CNVs in the cohort. METHODS: We have collected tissue and/or blood samples from 25 patients with anorectal malformations, esophageal atresia, or hydronephrosis, and screened for pathogenic CNVs using array comparative genomic hybridization (array-CGH). RESULTS: We detected pathogenic aberrations in 2/25 patients (8%) and report a novel possible susceptibility region for esophageal atresia on 15q26.3. CNV analysis in different tissues from the same patients did not reveal evidence of tissue-specific mosaicism. CONCLUSION: Our study shows that it is important to perform clinical genetic investigations, including CNV analysis, in patients with congenital gastrointestinal malformations since this leads to improved information to families as well as an increased understanding of the pathogenesis.

Is Pouch Specific to Colon and Not Ileum?

BACKGROUND: Congenital Pouch Colon (CPC) is an anorectal anomaly with an incidence of 3.5:1 in males and females, respectively. We have earlier reported CPC to be quite prevalent in north Indian tertiary care centers. OBJECTIVE: In this article, we deliberate on the possible causes associated with CPC bringing the manifestation of the disease. In addition, we throw insights on the effective role of this congenital anomaly in Colon and provide systems genomic evaluation by comparing our recent analysis to that of Colon and Ileum based on Next-Generation Sequencing (NGS) studies. CONCLUSION: In this commentary article, we argue that a host of epigenetic factors could be the reason why the disease is manifested in colon alone. We further hypothesize on the few unmet challenges linking epigenetics to understand the genetic variants.

Differentiating presacral masses in anorectal malformations and isolated sacrococcygeal teratomas.

PURPOSE: Presacral masses associated with anorectal malformations (ARM) are most frequently dermoid or teratomas. Sacrococcygeal teratoma (SCT), in isolation, is a different condition. There are limited data comparing the two. The aim of this study was to compare presacral masses associated with ARM and isolated SCTs. METHODS: A retrospective review was performed from 1979 to 2018. Patients with presacral masses and associated ARM (n = 39) were identified and compared to patients with isolated SCTs (n = 32). RESULTS: Those with presacral mass and ARM had a lower proportion of immature and mixed teratomas by pathology and a longer time to mass resection. They had higher percentages of sacral anomalies (76% versus 9%), tethered cord (50% versus 6%), and other anomalies (51% versus 9%). For long-term bowel function, patients with presacral mass and ARM were more likely to be fecally incontinent and require enemas (59% versus 11%). Regarding isolated SCTs, 4% recurred with a time to recurrence of 7 months. CONCLUSIONS: Compared to patients with isolated SCT, patients with presacral mass and ARM had lower grade tumors. In addition, they had a higher proportion of sacral defects and other congenital defects, as well as worse bowel function outcomes.

Presacral masses and sacrococcygeal teratomas in patients with and without anorectal malformations: A single institution comparative study.

BACKGROUND: Despite variability at presentation, presacral masses in patients with and without anorectal malformations (ARM) appear histologically similar. The purpose of this study was to identify differences in oncologic outcomes between these two groups. METHODS: A retrospective review was performed utilizing our institutional cancer and colorectal and pelvic reconstruction databases for patients with presacral masses and sacrococcygeal teratomas between 1990 and 2017. Data captured included age at surgical resection, type of ARM, tumor location within the pelvis, tumor histopathology, tumor size, adjuvant chemotherapy, recurrence, and follow-up. RESULTS: Forty-six patients comprised our cohort, of whom 12 had an ARM. The median age was older at resection for those with an ARM (1.4 years; range 1 day to 29.4 years) compared to those without an ARM (9 days; range 0 days to 6.9 years) (p = 0.01). The mean tumor size was 2.5 cm in patients with an ARM compared to 6.0 cm in patients without an ARM (p = 0.036). All patients with ARM had exclusively intrapelvic tumors, and histopathology included mature teratoma (8), yolk sac tumor (1), lipoma (1), and unknown (2). Tumor location for patients with sacral and presacral masses without ARM included exclusively extrapelvic (10), primarily extrapelvic with large intrapelvic component (7), primarily intrapelvic with extrapelvic component (1), exclusively intrapelvic (8), and unknown (8). Histopathology for patients with presacral masses without ARM included mature teratoma (20), immature teratoma (7), yolk sac tumor (3), ganglioneuroma (1), neuroblastoma (1), benign epithelial cyst (1), and unknown (1). Tumor recurrence rate was similar between patients with ARM (n = 3, 25%) and those without an ARM (n = 5, 15%) (p = 0.41). The 5-year event free survival was 65% (95% CI: 25%-87%) in the group with ARM and 81% (95% CI: 60%-92%) in the group without ARM (p = 0.44). CONCLUSION: Sacral and presacral masses in patients with ARM are resected at a later age and are more likely to be intrapelvic. They appear histologically similar and have similar rates of recurrence and malignancy when compared to patients without ARM. LEVEL OF EVIDENCE: III TYPE OF STUDY: Retrospective comparative study.

Histopathologic and immunohistochemical findings in congenital anorectal malformations.

It remains controversial whether the distal rectal pouch should be either resected or used for reconstruction in anorectoplasty for the treatment of anorectal malformations (ARMs). Hence the aim of this study was to investigate whether ARMs were associated with a global neuromuscular maldevelopment of the terminal rectum specimens.There were 36 cases of ARMs (25 recto-bulbar fistula and 11 recto-prostatic fistula) and 10 healthy controls. The hematoxylin and eosin and Masson trichrome stain were used to conduct the histologic examination. The immunohistochemistry (IHC) and Western blot were conducted to analyze the neuron-specific enolase (NSE), S-100 protein, interstitial cells of Cajal marker (C-kit) within the rectal specimens in control group and ARM group.The most frequently observed histologic findings in mucosa were inflammation, congestion, eroded, and hemorrhage in the ARM cases. Submucosal inflammation and congestion were the most common submucosal findings in the ARM cases. Disrupted muscularis propria was observed in 60% of ARM cases. Mature ganglionic cells were reduced and muscularis propria showed reduced and patchy positivity for NSE, S-100, and C-kit protein in ARM group compared to that in control group according to IHC. Western blotting showed the expression levels of NSE, S-100, and C-kit were lower in the ARM group than that in the control group (P < .01).Histopathologic and IHC findings suggest that the distal rectal pouch has distinct defects in the neuromusculature. So it suggested that ARMs are abnormally developed tissue and need to be resected for better functional outcomes of the remaining gut.

FOXD3/FOXD4 is required for the development of hindgut in the rat model of anorectal malformation.

Congenital anorectal malformation is the most common digestive tract malformation in newborns. It has been reported that FOXD3/FOXD4, a forkhead transcription factor, regulates the generation, migration, and differentiation of neural crest cells. However, whether FOXD3/FOXD4 takes part in anorectal malformation remains unclear. In the present study, we used ethylene thiourea to induce the animal models of anorectal malformation in rat embryos and to interrogate the role of FOXD3/FOXD4 in anorectal malformation pathogenesis. Hindgut samples of the animal models were collected at E15, E17, E19, and E21 days of age. The expression of FOXD3/FOXD4 was detected by immunohistochemistry, western blot, and quantitative real-time fluorescence PCR. By immunohistochemical staining, FOXD3/FOXD4 was observed in epithelial cells of the rectum and the anus both in normal and rat embryos with anorectal malformation. Expression level analysis by western blot indicated that FOXD3/FOXD4 expression increased in ethylene thiourea-induced anorectal malformation groups. mRNA expression as determined by quantitative real-time fluorescence PCR analysis was consistent with the western blot results. Tentative conclusions were drawn that FOXD3/FOXD4 is expressed in the hindgut in rat embryos and is upregulated in anorectal malformation. FOXD3/FOXD4 is required for the development of the hindgut, and its aberrant expression may be an important factor leading to the incidence of anorectal malformation. Impact statement Congenital anorectal malformation (ARM) is the most common digestive tract malformation in newborns. The pathophysiological ground remains unclear. In this study, we used animal models of ARM for the first time to interrogate the role of FOXD3/FOXD4 in ARM pathogenesis. The animal models of ARM were successfully induced by ethylene thiourea (ETU) in rat embryos providing a strong basis for pathogenesis study of this disease. Expression analysis of FOXD3/FOXD4 was carried out in these models, and the results shape a deeper understanding of FOXD3/FOXD4 being required for the normal development of the hindgut. The aberrant expression of FOXD3/FOXD4 may be an important factor leading to ARM incidence.

Spatiotemporal expression of proprotein convertase subtilisin/kexin type 5 in the development of anorectal malformations in fetal rats.

This study examined the expression patterns of proprotein convertase subtilisin/kexin type 5 (Pcsk5) during anorectal development in normal and anorectal malformations (ARM) rat embryos, determine the possible role of Pcsk5 in the pathogenesis of ARM. An ARM rat model was developed by the administration of ethylenethiourea gestational day 10 (GD10). Embryos were harvested by surgical excision from GD13 to GD16, and the spatiotemporal expression of Pcsk5 was evaluated, using immunohistochemistry staining, Western blotting and real time RT-PCR. Immunohistochemistry staining in normal embryos revealed that Pcsk5 was abundantly expressed on the epithelium of the cloaca (CL) on GD13. On GD14 and GD15, positive cells were noted on the urorectal septum and the thin anal membrane. However, the epithelium of the CL of ARM embryos only faintly expressed Pcsk5 from GD13 to GD15. Western blotting and real time RT-PCR showed time-dependent increase of Pcsk5 expression in the developing hindgut. Pcsk5 expression levels were lower in the ARM group from GD14 to GD16 (p ≤ 0.05). These results indicate that downregulation of Pcsk5 during cloaca development into the rectum and urethra might be related to the formation of ARMs.

Impact of sample collection participation on the validity of estimated measures of association in the National Birth Defects Prevention Study when assessing gene-environment interactions.

To better understand the impact that nonresponse for specimen collection has on the validity of estimates of association, we examined associations between self-reported maternal periconceptional smoking, folic acid use, or pregestational diabetes mellitus and six birth defects among families who did and did not submit buccal cell samples for DNA following a telephone interview as part of the National Birth Defects Prevention Study (NBDPS). Analyses included control families with live born infants who had no birth defects (N = 9,465), families of infants with anorectal atresia or stenosis (N = 873), limb reduction defects (N = 1,037), gastroschisis (N = 1,090), neural tube defects (N = 1,764), orofacial clefts (N = 3,836), or septal heart defects (N = 4,157). Estimated dates of delivery were between 1997 and 2009. For each exposure and birth defect, odds ratios and 95% confidence intervals were calculated using logistic regression stratified by race-ethnicity and sample collection status. Tests for interaction were applied to identify potential differences between estimated measures of association based on sample collection status. Significant differences in estimated measures of association were observed in only four of 48 analyses with sufficient sample sizes. Despite lower than desired participation rates in buccal cell sample collection, this validation provides some reassurance that the estimates obtained for sample collectors and noncollectors are comparable. These findings support the validity of observed associations in gene-environment interaction studies for the selected exposures and birth defects among NBDPS participants who submitted DNA samples.