Spondylocostal dysostosis, anal and genitourinary malformations in a fetal case: A new case of Casamassima–Morton–Nance syndrome?

Spondylocostal Dysostosis with Anal Atresia and Urogenital Anomalies in a Young Infant: First Case Entity of Casamassima-Morton-Nance Syndrome from Asia

Casamassima-Morton-Nance syndrome (CMNS) includes a heterogeneous group of spondylocostal dysostosis along with anal atresia and genitourinary abnormalities. In 1981, Casamassima et al first described the syndrome in a fetus, and since then, only seven such cases have been reported so far. CMNS phenotype shows a significant clinical variability as documented in the reported cases. Etiology remains unknown yet, and it carries a poor prognosis. Here, we reported on a young female infant born out of nonconsanguineous marriage with normal karyotype and spondylocostal dysostosis, anal and genitourinary malformations suggesting CMNS. Ours is the eighth, and first case entity of CMNS reported from Asia as per the literature search. In our case, the additional feature of bilateral clubfoot has not been documented earlier in the literature. It extends the clinical spectrum of the syndrome and prompts us to consider it a close differential diagnosis to VACTERL (vertebral defects, anal atresia, cardiac malformations, tracheoesophageal fistula/esophageal atresia, renal anomalies, limb abnormalities) syndrome, which is commonly known and diagnosed. It also raises the question of whether cases of CMNS are being misdiagnosed as VACTERL syndrome due to its rarity.

Etiologies of uterine malformations

Ranging from aplastic uterus (including Mayer-Rokitansky-Kuster-Hauser syndrome) to incomplete septate uterus, uterine malformations as a group are relatively frequent in the general population. Specific causes remain largely unknown. Although most occurrences ostensibly seem sporadic, familial recurrences have been observed, which strongly implicate genetic factors. Through the study of animal models, human syndromes, and structural chromosomal variation, several candidate genes have been proposed and subsequently tested with targeted methods in series of individuals with isolated, non-isolated, or syndromic uterine malformations. To date, a few genes have garnered strong evidence of causality, mainly in syndromic presentations (HNF1B, WNT4, WNT7A, HOXA13). Sequencing of candidate genes in series of individuals with isolated uterine abnormalities has been able to suggest an association for several genes, but confirmation of a strong causative effect is still lacking for the majority of them. We review the current state of knowledge about the developmental origins of uterine malformations, with a focus on the genetic variants that have been implicated or associated with these conditions in humans, and we discuss potential reasons for the high rate of negative results. The evidence for various environmental and epigenetic factors is also reviewed. © 2016 Wiley Periodicals, Inc.

Fetus with Casamassima-Morton-Nance Syndrome and Limb-Body Wall Defect: Presentation of a Novel Association and Review of the Phenotype

In 1981, Casamassima and colleagues described an autosomal recessive syndrome of spondylocostal dysostosis associated with anal and urogenital anomalies. Here, I describe 1 new fetus who presented with limb-body wall defect as a novel association, compile 7 patients, and review the clinical phenotype of Casamassima-Morton-Nance syndrome. This appears to be the 1st Casamassima-Morton-Nance syndrome fetus with this complex malformation. In light of this manifestation, a detailed comparative phenotypic analysis of published patients revealed a heterogeneous syndrome with significant clinical variability. Accordingly, it is proposed that Casamassima-Morton-Nance syndrome should be considered in those patients with the combination of a short and asymmetric thorax with rib and vertebral anomalies and scoliosis (spondylocostal-like pattern), anal atresia, absent external genitalia, renal and urethral abnormalities (caudal dysgenesis complex), craniofacial dysmorphic features (mainly flat nose with anteverted nares, low-set/abnormal ears, and short neck), hydrops, oligohydramnios, and a poor clinical outcome.

A new case of Casamassima-Morton-Nance (CMN) syndrome presenting prenatally as VACTERL association

Casamassima-Morton-Nance (CMN) syndrome (OMIM 271520) has clinical overlap with spondylocostal dysostosis and Vertebral, Anorectal, Cardiac, Tracheo-Esophageal, Radial/Renal, Limb (VACTERL) association but with consistent features of anal and urogenital abnormalities, particularly ambiguous genitalia. Since the original report, it has become clear that the combination of vertebral segmentation abnormalities, rib abnormalities, and urogenital anomalies may enable prenatal diagnosis of CMN by ultrasound. CMN syndrome is an important diagnosis to consider prenatally because of the generally poor prognosis compared to the more common VACTERL association. Here we present the seventh reported case of CMN syndrome. Prenatally presenting features of multiple segmentation anomalies within the spine, a left multi-cystic dysplastic kidney, marked pelvicaliectasis with abnormal renal parenchyma and a small stomach were suggestive of VACTERL association. There was severe oligohydramnios. Termination of pregnancy was performed at 22 weeks gestation and autopsy revealed dysmorphic coarse facial features, marked scoliosis, bilateral talipes, ambiguous external genitalia, and anal atresia. These features were highly suggestive of CMN syndrome. The important discriminating feature of ambiguous genitalia was not apparent on the prenatal ultrasound in this case because of severe oligohydramnios but we suggest that careful prenatal ultrasound assessment of the genitalia in cases of suspected VACTERL is important in differentiating these two conditions.

The vertebrate segmentation clock and its role in skeletal birth defects

The segmental structure of the vertebrate body plan is most evident in the axial skeleton. The regulated generation of somites, a process called somitogenesis, underlies the vertebrate body plan and is crucial for proper skeletal development. A genetic clock regulates this process, controlling the timing of somite development. Molecular evidence for the existence of the segmentation clock was first described in the expression of Notch signaling pathway members, several of which are expressed in a cyclic fashion in the presomitic mesoderm (PSM). The Wnt and fibroblast growth factor (FGF) pathways have also recently been linked to the segmentation clock, suggesting that a complex, interconnected network of three signaling pathways regulates the timing of somitogenesis. Mutations in genes that have been linked to the clock frequently cause abnormal segmentation in model organisms. Additionally, at least two human disorders, spondylocostal dysostosis (SCDO) and Alagille syndrome (AGS), are caused by mutations in Notch pathway genes and exhibit vertebral column defects, suggesting that mutations that disrupt segmentation clock function in humans can cause congenital skeletal defects. Thus, it is clear that the correct, cyclic function of the Notch pathway within the vertebrate segmentation clock is essential for proper somitogenesis. In the future, with a large number of additional cyclic genes recently identified, the complex interactions between the various signaling pathways making up the segmentation clock will be elucidated and refined.