Establishment of a rescue program for anorectal malformations induced by retinoic acid in mice

Risk factors for anorectal and associated malformations in German children: A 10-year analysis

BACKGROUND

Incidences of anorectal malformations (ARM) occur in 1 of 2000-5000 live births and up to 64% have associated malformations (ARMa). The aim of the study was to evaluate possible prenatal risk factors for ARM in a tertiary hospital.

METHODS

A case-control design was used to compare risk factors in ARM (n = 44) to a control group (CG; n = 26). We used modified prenatal questionnaires, analyzed mothers' prenatal records and participants completed a structured interview. Endpoints were medical history, drug consumption, occupational risk factors, and time point of diagnosis, associated malformations and sensitivity of radiological imaging.

RESULTS

Our results showed that ARM couples had a significantly higher age difference (p = 0.028) compared to CG. ARM mothers had more abnormalities during pregnancy (p = 0.002), more positive vaginal smears of group B streptococci (p = 0.024), urogenital infections (p = 0.005), gestosis (p = 0.03), emesis (p = 0.025) and higher numbers of chronic diseases (p = 0.018). ARM mothers took less medication during pregnancy (p = 0.013) than CG mothers including folic acid (p = 0.041); their intake of iodine tablets was significantly higher (p = 0.035) and they continued smoking for longer (p = 0.036) than CG mothers, and they had more stillbirths (p = 0.035). In using illegal drug and alcohol use, the groups did not show significant differences. ARMa was present in 68.1% (n = 30), of which 45.5% were of urogenital origin (n = 20). ARM diagnosis was made on the first day of life in 72.7% (n = 32), while diagnosis was delayed in 12 patients (27.3%).

CONCLUSION

A combination of different risk factors seem to be associated with the development of ARM, which takes place at an early stage (<7th week) of pregnancy. Therefore, risk factors influencing fetal development must be critically considered. We advocate an interdisciplinary assessment in unclear clinical findings on first day of life to optimize the therapy and positively influence the outcome.

Folic acid rescues all-trans retinoic acid-induced anorectal malformations in rats

BACKGROUND

To investigate whether folic acid (FA) can rescue anorectal malformations (ARMs) induced by all-trans retinoic acid (ATRA) in rats.

METHODS

Pregnant Sprague-Dawley rats were randomly divided into three groups. In the model group, rats were administered ATRA (110 mg/kg) by gavage on the 10th day of gestation (E10.5). Rats in the rescue group were administered FA (40 mg/kg) by gavage 0.5 and 12 hr after treatment with ATRA. All fetuses were harvested on E20.5 using cesarean section and examined for ARMs. We recorded the weight, body length, tail length, and associated malformations of all the embryos. Hematoxylin and eosin staining was used to analyze the histopathology of the fetuses.

RESULTS

Control rats did not show any abnormalities. ARMs, tail deformities (less than half of normal length), and neural tube defects were found in 97.98% (97/99), 92.93% (92/99), and 32.32% (32/99) of the rats in the model group, respectively. The incidence of ARMs and tail deformities were 48.57% (51/105) and 35.24% (37/105), respectively, in the rescue rats; no neural tube defects were observed in these rats. The weight, body length, and tail length of the fetal rats in the rescue group were more than those in the model group, but less than those in the control group.

CONCLUSION

Taken together, FA rescued ARMs induced by ATRA in rats. Thus, FA may reduce the incidence of associated malformations and improve the growth and development of fetal rats.

Abnormal serum vitamin A levels and retinoic acid receptor α expression patterns in children with anorectal malformation

BACKGROUND

Anorectal malformation (ARM) is known to be associated with maldevelopment of the enteric nervous system (ENS), and vitamin A (VA) and its metabolite retinoic acid (RA) play important roles in ENS development. Thus, our aim was to investigate serum VA levels in ARM newborns and RA receptor (RAR) expression in the rectum of ARM patients and animal models.

METHODS

Serum VA concentrations were detected in newly diagnosed ARM neonates (n = 32) and neonates with non-alimentary tract malformations (n = 30). Intestinal specimens were divided into three groups: rectum from ARM patients (n = 30), colon from a stoma (n = 30) and rectum from controls (n = 4). RAR mRNA expression was evaluated by RT-qPCR. Rectum specimens from ARM patients were divided into two groups by postoperative pathology: the normal and lesion ganglion cell groups. Immunohistochemistry and Western blot were employed to detect RARα protein expression in rectum specimens. In addition, the ARM mouse model was induced by all-trans retinoid acid (ATRA), and the expression levels of RARα and the neuronal marker NeuN in the rectum of mice on embryonic day 16.5-18.5 (E16.5-18.5) were investigated.

RESULTS

The serum concentration of VA in ARM neonates was lower than that in control neonates (P < 0.0001), and RARα mRNA expression was lower in the rectum specimens from ARM patients than in the colon specimens from a stoma and the rectum specimens from controls (P < 0.05); there was no significant difference between the colon from a stoma and the rectum from controls. RARα protein was expressed in the nucleus of ganglion cells and nerve fibers, and RARα protein expression in the lesion ganglion cell group was significantly lower than that in the normal ganglion cell group (P < 0.01). Compared with the control mice, ARM mice at E16.5-18.5 showed decreased fluorescence intensity of RARα and NeuN in the rectum. RARα and NeuN mRNA expression in the rectum on E16.5-18.5 was lower in ARM mice than in control mice (P < 0.05).

CONCLUSION

Serum VA concentration and the RARα expression pattern are abnormal in the rectum in ARM and may contribute to the ENS maldevelopment in ARM.

Anorectal malformation associated with a mutation in the P63 gene in a family with split hand-foot malformation

PURPOSE

The aims of this study were to identify the mutation gene of a Chinese family with anorectal malformation (ARM) associated with split hand-foot malformation and to determine the spatiotemporal expression of the mutated gene during hindgut and anorectum development in human embryos.

METHOD

A Chinese family with intrafamilial clinically variable manifestation was analyzed and primers were designed for exons 3-14 of P63, DLX5, DLX6, DAC, and HOXD13 as candidate genes and direct sequence analysis of the exons was performed. Immunohistochemical study of mutated gene in the hindgut and anorectum of human embryos of 4th-10th weeks was performed.

RESULT

Affected individuals were found to have an Arg227Gln P63 gene mutation. From the 4th-10th weeks of gestation of the human embryo, the P63-positive cells were mainly located on the epithelium of the apical urorectal septum, hindgut, and cloacal membrane. After the anorectum ruptured during the 8th week, the P63 remained strongly immunoreactive on the epithelium of the anal canal and urethra, but the mucous membrane of the rectum exhibited no reaction.

CONCLUSIONS

The mutation identified strongly suggests a causal relationship between the ARM phenotype and P63. The expression of P63 was persistently active during the dynamic and incessant septation of the cloaca and hindgut, suggesting that P63 may play a pivotal role in the morphogenesis of the hindgut and anorectum.