Disorganization in mice and humans and its relation to sporadic birth defects

Sixteenth-century German woodcut of a male infant with possible disorganization

History has preserved a beautiful 16th century woodcut print, which depicts an infant with several malformations. The German inscription describes the infant's hypotonia and ectopic growths, and the image itself shows a child with an ectopic accessory third lower limb, a large papilla, and an omphalocele-like growth. The 'case' bears striking similarity to reported human cases of the disorganization (Ds) syndrome. This article describes the woodcut, describes Ds, and then explains how the image may represent the earliest depiction of Ds in history.

Congenital upper eyelid coloboma: embryologic, nomenclatorial, nosologic, etiologic, pathogenetic, epidemiologic, clinical, and management perspectives

Purpose:

To review the recent literature and describe the authors’ experience with congenital upper eyelid coloboma.

Methods:

In this review, we will summarize the embryologic and etiopathogenetic bases of congenital upper eyelid coloboma, and study the published clinical reports. We will also attempt to briefly shed some light on the rarer syndromic curiosities associated with upper eyelid coloboma.

Results:

Congenital upper eyelid colobomas are one of the few nontraumatic oculoplastic emergencies that may occasionally present in the first few days of life with a corneal ulcer and may even present with impending perforation. They can present with or without corneopalpebral adhesions, may be isolated findings or a part of a larger spectrum of congenital anomalies as in the case of Fraser syndrome or Goldenhar syndrome, or could be associated with other rare curiosities that could challenge the clinician with a huge diagnostic dilemma.

Conclusions:

Existing literature dealing with congenital colobomas of the upper eyelid is fraught with nosologic problems, confusing etiologies, and overlapping clinical features. We attempted to clarify the salient clinical features, outline the management principles, and until a time in the not-so-distant future where advances in molecular genetic testing would help redefine the etiology and the diverse clinical spectrum of genetic diseases associated with upper eyelid colobomas, we propose a simplified classification scheme based on the relation of the coloboma to the cornea, the presence or absence of systemic features, and all the syndromic and nonsyndromic associations of congenital coloboma of the upper eyelid known today.

In this review, the authors will describe the pathogenesis of upper eyelid coloboma, suggest a new simplified classification system, describe the clinical picture in detail, clarify the various syndromic associations of upper eyelid coloboma, and lay out the basic surgical principles of management.

Patient with disorganization syndrome: surgical procedures, pathology, and potential causes

BACKGROUND

The human disorganization syndrome (HDS) is an extremely rare malformation syndrome that presents with a severe pattern of defects affecting different structures.

METHODS

We describe a newborn girl presenting with HDS. Her clinical features included a large appendage arising from the right buttock as the only alteration, with size and shape of a lower member-like structure, and a pedicle of the extra limb structure. The surgical observations, the pathological results, evolution up to 6 months of age, and their potential causes are described, as well as a review of the literature.

RESULTS

The MRI procedure also detected a multicystic mass located at the presacral region of the pelvis and perineum, without any dysraphism or other medullary anomalies. The X-ray showed that the member-like structure had an iliac wing, femur, tibia, fibula, and aberrant metatarsals. The review of the literature shows disparate defects of the published cases with HDS, which include some features pathogenically not related with this syndrome.

CONCLUSION

We highlight the need to maintain restricted the clinical diagnosis for HDS to those concordant with a great disorganization of morphogenetic inductions affecting the three germ layers, which occur during the first four weeks of development. This is crucial to: (a) perform a correct diagnosis, which is essential to establish the prognosis and surgery procedures, (b) identify which is/are the cause/s, and (c) the adequate genetic counseling.

A novel intergenic ETnII-β insertion mutation causes multiple malformations in polypodia mice

Mouse early transposon insertions are responsible for ∼10% of spontaneous mutant phenotypes. We previously reported the phenotypes and genetic mapping of Polypodia, (Ppd), a spontaneous, X-linked dominant mutation with profound effects on body plan morphogenesis. Our new data shows that mutant mice are not born in expected Mendelian ratios secondary to loss after E9.5. In addition, we refined the Ppd genetic interval and discovered a novel ETnII-β early transposon insertion between the genes for Dusp9 and Pnck. The ETn inserted 1.6 kb downstream and antisense to Dusp9 and does not disrupt polyadenylation or splicing of either gene. Knock-in mice engineered to carry the ETn display Ppd characteristic ectopic caudal limb phenotypes, showing that the ETn insertion is the Ppd molecular lesion. Early transposons are actively expressed in the early blastocyst. To explore the consequences of the ETn on the genomic landscape at an early stage of development, we compared interval gene expression between wild-type and mutant ES cells. Mutant ES cell expression analysis revealed marked upregulation of Dusp9 mRNA and protein expression. Evaluation of the 5′ LTR CpG methylation state in adult mice revealed no correlation with the occurrence or severity of Ppd phenotypes at birth. Thus, the broad range of phenotypes observed in this mutant is secondary to a novel intergenic ETn insertion whose effects include dysregulation of nearby interval gene expression at early stages of development.

Mobile genetic elements, particularly early transposons (ETn), cause malformations by inserting within genes leading to disruption of exons, splicing or polyadenylation. Few mutagenic early transposon insertions have been found outside genes and the effects of such insertions on surrounding gene regulation is poorly understood. We discovered a novel intergenic ETnII-β insertion in the mouse mutant Polypodia (Ppd). We reproduced the mutant phenotype after engineering the mutation in wild-type cells with homologous recombination, proving that this early transposon insertion is Ppd. Mutant mice are not born in expected Mendelian ratios secondary to loss after E9.5. Embryonic stem cells from mutant mice show upregulated transcription of an adjacent gene, Dusp9. Thus, at an early and critical stage of development, dysregulated gene transcription is one consequence of the insertion mutation. DNA methylation of the ETn 5′ LTR is not correlated with phenotypic outcome in mutant mice. Polypodia is an example of an intergenic mobile element insertion in mice causing dramatic morphogenetic defects and fetal death.

Amnion formation in the mouse embryo: the single amniochorionic fold model

BACKGROUND

Despite the detailed knowledge obtained over the last decade on the molecular regulation of gastrulation in amniotes, the process of amnion development has been poorly described and illustrated in mice, and conflicting descriptions exist. Understanding the morphogenesis and development not only of the early mouse embryo, but also of its extraembryonic tissues, is crucial for correctly interpreting fate-mapping data and mouse mutants with gastrulation defects. Moreover, the recent isolation from amnion of cells with stem cell features further argues for a better understanding of the process of amnion formation. Here, we revisit the highly dynamic process of amnion formation in the mouse. Amnion development starts early during gastrulation and is intimately related to the formation of the exocoelom and the expansion of the amniotic fold. The authoritative description involves the fusion of two amniotic folds, a big posterior and a smaller anterior fold. We challenged this 'two amniotic folds' model by performing detailed histomorphological analyses of dissected, staged embryos and 3D reconstructions using historical sections.

RESULTS

A posterior fold of extraembryonic ectoderm and associated epiblast is formed early during gastrulation by accumulation of extraembryonic mesoderm posterior to the primitive streak. Previously called the "posterior amniotic fold", we rename it the "amniochorionic fold" (ACF) because it forms both amnion and chorion. Exocoelom formation within the ACF seems not to involve apoptosis within the mesoderm. The ACF and exocoelom expand without disrupting the anterior junction of epiblast, extraembryonic ectoderm and visceral endoderm. No separate anterior fold is formed; its absence was confirmed in 3D reconstructions. Amnion and chorion closure is eccentric, close to the anterior margin of the egg cylinder: we name it the "anterior separation point".

CONCLUSIONS

Here, we reconcile previous descriptions of amnion formation and provide new nomenclature, as well as an animation, that clarify and emphasize the arrangement of the tissues that contribute to amnion development and the dynamics of the process. According to our data, the amnion and the chorion are formed by a single amniochorionic fold initiated posteriorly. Finally, we give an overview on mutant mouse models with impaired amnion development.

All-trans retinoic acid-induced ectopic limb and caudal structures: murine strain sensitivities and pathogenesis

Treatment of pregnant mice at the egg cylinder stage with retinoic acid (RA) has caused ectopic hindlimbs in the offspring. Proposed causes of ectopic hindlimbs include homeotic transformation or multiple axis formation. Two mouse strains were determined to be divergent in susceptibility to this malformation (C57BL/6N, highly sensitive; SWV/Fnn, less sensitive). Ectopic limbs were hindlimbs (expressing Pitx1 and Tbx4 but not Tbx5), yet they also expressed the predominantly forelimb Hoxb8. Ectopic body axis formation was indicated by gene expression for ectopic primitive streaks, notochords, and nodes, as well as inhibition of anterior visceral endoderm and mesodermal migration. The earlier in development that embryos were examined, the higher the rate of ectopic hindlimb development and axis formation. Ectopic axis formation and cell migration inhibition had the same strain susceptibility as the dysmorphogenesis. We propose that all extra hindlimbs were derived from ectopic axis formation, perturbation of which is genetic background dependent.

Syndromes and Disorders Associated with Omphalocele (II): OEIS Complex and Pentalogy Of Cantrell

Omphalocele-exstrophy-imperforate anus-spinal defects (OEIS) complex is characterized by a combination of omphalocele, exstrophy of the bladder, an imperforate anus, and spinal defects. Pentalogy of Cantrell is characterized by a combination of a midline supraumbilical abdominal wall defect, a defect of the lower sternum, a defect of the diaphragmatic pericardium, a deficiency of the anterior diaphragm, and congenital cardiac anomalies. This article provides a comprehensive review of OEIS complex and pentalogy of Cantrell, including the pathogenesis, prenatal diagnosis, differential diagnosis, and associated malformations. Omphalocele is an important sonographic marker for OEIS complex and pentalogy of Cantrell. Prenatal detection of an abdominal wall defect associated with multiple midline defects should alert one to the possibility of OEIS complex and pentalogy of Cantrell and prompt the genetic investigation and counseling of the disorders.

Description and genetic mapping of Polypodia: an X-linked dominant mouse mutant with ectopic caudal limbs and other malformations

In this report we present a spontaneous mouse mutant, named Polypodia (Ppd), that primarily exhibits ectopic, ventral/caudal limbs and associated pelvic girdle malformation or duplication. Less penetrant features include diphallia, microphthalmia, small kidney, curled or kinked tail, forelimb anomaly, and skin papillae. Ppd mice have a normal karyotype and no large-scale genomic deletions or insertions by BAC-based array comparative genomic hybridization (CGH). Ppd is X-linked dominant with approximately 20% penetrance on the C3H background and maps to X:61.6 Mb-X:71.24 Mb. The limb and a subset of the nonlimb anomalies are similar to those in offspring from retinoic acid-treated dams at E4.5-5.5 and feature overlap with the Disorganization mouse mutant and human patients with ectopic legs. We hypothesize that Ppd affects very early steps in the formation of caudal structures including limb and appendage number. The existence of noncaudal anomalies implies the involvement of Ppd in a broad array of cell fate decisions.

Non-multifactorial neural tube defects

Although most neural tube defects (anencephaly, spina bifida) occur as isolated malformations, a substantial proportion are attributable to chromosome anomalies, known teratogens, or component manifestations of multiple anomaly syndromes. This review describes known chromosome alterations and the candidate genes residing in the altered region, as well as syndromes associated with neural tube defects and causative genes, if known.

Clefting, amniotic bands, and polydactyly: A distinct phenotype that supports an intrinsic mechanism for amniotic band sequence

Amniotic band sequence (ABS) is a well-described condition involving a variety of congenital anomalies in association with fibrous bands. However, many cases are associated with birth defects that are not readily explained by the mechanism of fibrous strings entangling body parts and causing disruption of the fetal structures. The most common of these is typical cleft lip and palate (CLP). Here we describe such a case, with typical ABS limb defects and constriction bands, along with CLP, supernumerary left nipple, polydactyly, and a skin papilla. This case is nearly identical to a child previously described by Guion-Almieda and Richieri-Costa [2000] and may, therefore, represent a previously unrecognized syndrome that overlaps with ABS. Furthermore it may be that cases with ABS-like anomalies associated with CLP represent a different condition, possibly caused by mutations in the genes Disorganization, p63, or IRF6.

Human disorganization complex, as a polytopic blastogenesis defect: a new case

We describe a baby girl of 4,000 g and 55 cm with supernumerary, malformed, and partially duplicated lower limbs, malformed and partially duplicated pelvis, spina bifida, coccygeal dermal sinus, ectopic anus located in the right buttock, duplicated internal genitalia, rectovaginal fistula, ileal atresia, Meckel diverticulum, and various renal system anomalies. We think that this phenotype is a new case of disorganization in humans (DsH) and postulate that this condition constitutes a polytopic defect of the blastogenesis. In this case, the presence of a malformation pattern involving structures in different parts of the body and organs derived from all of the germ layers, suggests that the pathogenetic event most probably occurred during blastogenesis affecting various progenitors fields.

Isolated Gastroschisis in Successive Siblings: A Case Report and Review of the Literature

BACKGROUND

Although gastroschisis occurring in siblings is rare, a number of cases have been reported. A variety of inheritance patterns and embryologic explanations have previously been suggested. Young maternal age appears to be a consistent risk factor.

CASE

At age 17 years, Melanie (pseudonym) presented at 36 weeks' gestation and delivered a boy affected by gastroschisis. This condition had not been noted at a 13-week prenatal ultrasound. At age 18 years, Melanie delivered a second son with gastroschisis. There was no history of gastroschisis or other congenital anomaly in either parent's family. Melanie denied the use of alcohol, cigarettes, street drugs, and medications. She has since delivered 2 healthy children.

CONCLUSION

There is a need for preconception counselling for women who have experienced a pregnancy complicated by gastroschisis, to discuss the low but possible risk of recurrence. Early ultrasound may allow for detection or reassurance.

Omphalocele-exstrophy-imperforate anus-spinal defects (OEIS) in triplet pregnancy after IVF and CVS

BACKGROUND

Omphalocele-exstrophy-imperforate anus-spinal defects (OEIS) complex is a rare sporadic condition.

CASE

We identified an infant with major malformations resembling OEIS. He was the product of a 30-week triplet pregnancy conceived by in vitro fertilization (IVF) and evaluated by chorionic villi sampling (CVS). In this article, we review the possible pathogenetic mechanisms in this case, including IVF, multiple gestation, trauma to the uterus or uterine vessels following CVS, and placenta accreta.

CONCLUSIONS

We conclude that the cumulative effects of all or some of these factors may have resulted in uteroplacental insufficiency adequate to produce this phenotype. This case provides additional evidence for the uterine vascular pathogenesis of OEIS complex in humans.

Lumbopedal skin pedicle in an infant with the amniotic band syndrome: a Disorganization-like defect?

A female infant is presented in whom anomalies not commonly seen in amniotic band syndrome (ABS) included non-anatomic lumbopedal union by a skin pedicle, anorectal malformation, meningocele, vertebral segmentation defects, longitudinal limb defects, vestigial feet and skin papillae. The unusual, non-band related malformations in the proposita showed similarity to the mouse mutant Disorganization (Ds). This report, supports the suggestion that Ds-like mutations may cause some cases with apparent ABS associated with "skin pedicles".

Asymmetry: molecular, biologic, embryopathic, and clinical perspectives

This overview of asymmetry addresses the following topics: chiral molecules; asymmetric signaling molecules, including N-cadherin, Shh, Fgf8, lefty1, lefty2, nodal, Pitx2, activin betaB, activin receptor IIA, and cSnR; situs abnormalities; asymmetric cell division; laterality in humans and animals; behavioral asymmetry in humans and animals; asymmetric embryopathies, including Tessier-type "clefts"; hemiasymmetries such as hemihyperplasia, hemihypoplasia, and hemiatrophy; asymmetric vascular syndromes, including Klippel-Trenaunay and Sturge-Weber syndromes; plagiocephaly of the synostotic and deformational types; somatic mosaicism, including a discussion of McCune-Albright syndrome, fibrous dysplasia, GNAS1 mutations, and Proteus syndrome.

Case of complex craniofacial anomalies, bilateral nasal proboscides, palatal pituitary, upper limbs reduction, and amnion rupture sequence: disorganization phenotype?

We report a case of a dizygotic twin with complex abnormalities of head, body, and limbs. The anomalies include the following: lateral and midline cleft upper lip, ectopic palatal pituitary, natal teeth, bilateral nasal proboscides with an absent nose, left microphthalmia with conjunctival-lined cyst, right ocular dysgenesis, bilateral retinal dysplasia, platybasia with skull asymmetry, hydrocephalus secondary to aqueductal atresia, brain hemispheric asymmetry with a parietal-occipital cortical flap, agenesis of posterior corpus callosum, absence of the olfactory nerves and left anterior cerebral artery, leptomeningeal and intraventricular heterotopias, right radial longitudinal terminal meromelia with constriction rings of fingers, partial syndactyly of the third and fourth left fingers, dorsiflexed great toes and pes equinovarus bilaterally, and multiple skin tags with a sacral appendage. Additionally, this twin's placental disc and extraplacental membranes were devoid of amnion. We regard these anomalies as a possible expression of the human homologue of the disorganization phenotype or another gene mutation. Nevertheless, an abnormality of blastogenesis with early damage to organizing tissues of the frontonasal region and limbs, or a vascular disruption, cannot be excluded. Early amnion rupture sequence (possible extraamniotic pregnancy with amniotic bands, limb reduction defects with Streeter bands, and multiple skin tags tapering into amniotic bands) was also present in this case, and may have acted as a contributing factor.