Upper limb phocomelia: A prenatal case of thrombocytopenia-absent radius (TAR) syndrome illustrating the importance of chromosomal microarray in limb reduction defects.

OBJECTIVE: To describe the ultrasonographic, pathologic and molecular findings in a fetus with TAR syndrome, and to illustrate the contribution of chromosomal microarray analysis (CMA) to the etiological investigation of fetal upper limb reduction defects. CASE REPORT: A 35-year-old woman was referred for Genetic Counseling after pregnancy termination for severe upper limb bilateral phocomelia detected in the second trimester. Fetal autopsy showed severe shortening of the arms and forearms. The fetal skeletal survey confirmed the absence of the radii, ulnae and humeri. CMA revealed an interstitial deletion in 1q21 including the RBM8A gene. Subsequent Sanger sequencing of this gene identified a hypomorphic mutant allele, c.-21G > A, confirming the diagnosis of TAR syndrome. CONCLUSION: The differential diagnosis of upper limb defects is broad. Identification of their cause is essential for adequate genetic counseling including prognosis and recurrence risk estimation. CMA should be considered in fetuses with upper limb reduction defects, especially when the thumbs are present.

An unnoticed variant of Sirenomelia with constellation of multiple anomalies

Sirenomelia is a rare fatal congenital anomaly, characterized by a single midline lower limb, urogenital anomalies, Potter's facies and a single umbilical artery. Approximately 400 cases have been reported in the literature. Based on the number of feet and the degree of lower limb bone fusion, it is classified into seven different types. Sirenomelia has been reported with associated anomalies involving multiple systems mainly of urogenital, respiratory as well as the alimentary tract system. In the present case, the authors reported an unnoticed variation in the fusion of lower limbs and its rare association with tracheoesophageal fistula

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Prenatal diagnosis of a 1.6-Mb 4p16.3 interstitial microdeletion encompassing FGFRL1 and TACC3 associated with bilateral cleft lip and palate of Wolf-Hirschhorn syndrome facial dysmorphism and short long bones.

OBJECTIVE: We present prenatal diagnosis of a 4p16.3 interstitial microdeletion associated with bilateral cleft lip and palate and short long bones on prenatal ultrasound, and we discuss the genotype-phenotype correlation. MATERIALS AND METHODS: A 32-year-old woman underwent amniocentesis at 22 weeks of gestation because of bilateral cleft lip and palate and short limbs on prenatal ultrasound. Conventional cytogenetic analysis was performed on cultured amniocytes and parental bloods. Oligonucleotide array comparative genomic hybridization (aCGH) was performed on the DNAs extracted from uncultured amniocytes, parental bloods and umbilical cord. Metaphase fluorescence in situ hybridization (FISH) was performed on cultured amniocytes. RESULTS: Amniocentesis revealed a karyotype of 46,XY. The parental karyotypes were normal. aCGH analysis on uncultured amniocytes revealed a 1.66-Mb interstitial microdeletion at 4p16.3 encompassing 23 Online Mendelian Inheritance of in Man (OMIM) genes including FGFRL1 and TACC3. The parents did not have such a deletion. The pregnancy was subsequently terminated, and a malformed fetus was delivered with typical Wolf-Hirschhorn syndrome (WHS) facial appearance and bilateral cleft lip and palate. aCGH analysis of the umbilical cord confirmed the prenatal diagnosis with a result of arr 4p16.3 (72,447-1,742,649) × 1.0 [GRCh37 (hg19)]. Metaphase FISH analysis of cultured amniocytes confirmed a 4p16.3 microdeletion. CONCLUSION: Haploinsufficiency of FGFRL1 and TACC3 at 4p16.3 can be associated with bilateral cleft lip and palate of WHS facial dysmorphism and short long bones. Prenatal diagnosis of facial cleft with short long bones should raise a suspicion of chromosome microdeletion syndromes.

Postaxial limb hypoplasia (PALH): the classification, clinical features, and related developmental biology.

Postaxial limb hypoplasia (PALH) is a group of nonhereditary diseases with congenital lower limb deficiency affecting the fibular ray, including fibular hemimelia, proximal femoral focal deficiency, and tarsal coalition. The etiology and the developmental biology of the anomaly are still not fully understood. Here, we review the previous classification systems, present the clinical features, and discuss the developmental biology of PALH.

Systematic radiographic evaluation of tibial hemimelia with orthopedic implications.

Tibial hemimelia is a rare lower-extremity pre-axial longitudinal deficiency characterized by complete or partial absence of the tibia. The reported incidence is 1 in 1 million live births. In this pictorial essay, we define tibial hemimelia and describe associated conditions and principles of preoperative imaging assessment for a child with tibial hemimelia. We also indicate the imaging findings that might influence the choice of treatment, describe the most widely used classification systems, and briefly discuss current treatment approaches.

Foetal fibular hemimelia with focal femoral deficiency following prenatal misoprostol use: A case report.

Misoprostol is a well known abortifacient. It can cause teratogenicity like Mobius sequence and terminal transverse limb defects. We report a rare case of proximal focal femoral deficiency with fibular hemimelia in a woman who had attempted abortion with self-administered misoprostol and later continued the pregnancy. Though the absolute risk of congenital malformations with its use is low ∼1%, this should be clearly communicated to the women requesting abortion to help them make fully informed reproductive health decisions.

Sirenomelia: a review of embryogenic theories and discussion of the differences from caudal regression syndrome.

OBJECTIVE: To discuss the pathological features of sirenomelia in the light of our 10 cases and review the current theories. METHODS: We identified 10 patients with sirenomelia from our hospital database. All clinical details and the autopsy features of 10 cases were noted. RESULTS: Of the 10 children with sirenomelia seven had bilateral renal agenesis, three had bladder agenesis and one had a renal hypoplasia. Single umbilical artery was found in 60% of children with sirenomelia. External genitalia was ambiguous in seven of 10 patients. CONCLUSIONS: Even though the etiology of caudal regression syndrome (CRS) and sirenomelia remains unknown we tend to believe that sirenomelia and CRS might be different entities.

Birth defects associated with perturbations in preimplantation, gastrulation, and axis extension: from conjoined twinning to caudal dysgenesis.

Congenital malformations represent approximately 3 in 100 live births within the human population. Understanding their pathogenesis and ultimately formulating effective treatments are underpinned by knowledge of the events and factors that regulate normal embryonic development. Studies in model organisms, primarily in the mouse, the most prominent genetically tractable mammalian model, have equipped us with a rudimentary understanding of mammalian development from early lineage commitment to morphogenetic processes. In this way, information provided by studies in the mouse can, in some cases, be used to draw parallels with other mammals, including human. Here, we provide an overview of our current understanding of the general sequence of developmental events from early cell cleavages to gastrulation and axis extension occurring in human embryos. We will also review some of the rare birth defects occurring at these stages, in particular those resulting in conjoined twinning or caudal dysgenesis.

Sirenomelia: a review on embryogenic enviromental theories, novel three-dimensional ultrasound imaging and first trimester diagnosis in a case of mosaic 69,XXX/46,XX fetus.

PURPOSE: Sirenomelia is caused by atrophy of the lower extremities that is commonly associated with gastrointestinal and urogenital malformations. METHODS: Embryogenic environmental theories and systematic review of the literature are reported. RESULTS: Genetic basis of the condition has been demonstrated in the animal model. In humans, association with de novo balanced translocation has only recently been documented. CONCLUSIONS: A case of triploidy mosaic fetus with sirenomelia and posterior fossa anomaly diagnosed at first trimester using novel three-dimensional ultrasound imaging techniques is presented.

Sirenomelia phenotype in bmp7;shh compound mutants: a novel experimental model for studies of caudal body malformations.

Sirenomelia is a severe congenital malformation of the lower body characterized by the fusion of the legs into a single lower limb. This striking external phenotype consistently associates severe visceral abnormalities, most commonly of the kidneys, intestine, and genitalia that generally make the condition lethal. Although the causes of sirenomelia remain unknown, clinical studies have yielded two major hypotheses: i) a primary defect in the generation of caudal mesoderm, ii) a primary vascular defect that leaves the caudal part of the embryo hypoperfused. Interestingly, Sirenomelia has been shown to have a genetic basis in mice, and although it has been considered a sporadic condition in humans, recently some possible familial cases have been reported. Here, we report that the removal of one or both functional alleles of Shh from the Bmp7-null background leads to a sirenomelia phenotype that faithfully replicates the constellation of external and internal malformations, typical of the human condition. These mutants represent an invaluable model in which we have analyzed the pathogenesis of sirenomelia. We show that the signaling defect predominantly impacts the morphogenesis of the hindgut and the development of the caudal end of the dorsal aortas. The deficient formation of ventral midline structures, including the interlimb mesoderm caudal to the umbilicus, leads to the approximation and merging of the hindlimb fields. Our study provides new insights for the understanding of the mechanisms resulting in caudal body malformations, including sirenomelia.

[Sirenomelia apus. Case report]. / Sirenomelia apus: reporte de un caso clínico.

We report a case of Sirenomelia. The mother began prenatal care in the second trimester. Transabdominal ultrasound was determined anhydramnios, cardiac abnormalities and lumbosacral spine. We obtained a single fetus of 21 weeks' gestation with fused lower extremities from the hip to finish in a stump without the presence of feet. Heart with transposition of the great vessels, among other birth defects. It was classified as symelia, Apodi apus, monopodio sirenoide, siren ectropodia, type VI. It is important to diagnose early, because it is a serious and deadly disorder.

Genetic and pathologic aspects of retinoic acid-induced limb malformations in the mouse.

Because all-trans retinoic acid (atRA) is teratogenic in all species tested and many of the specific defects induced are common across the phylogenetic spectrum, it would be logical to predict that murine strain differences in teratology to this agent are minimal. However, for specific defects, strain susceptibilities are vastly different. Studies with atRA have shown stark differences between C57BL/6 and SWV mouse strains in susceptibility to postaxial forelimb ectrodactyly and ectopic hindlimb formation, with the C57 strain being more susceptible for both defects. Various approaches were used to determine why these strains differ in susceptibility, but the mechanisms remain unknown. Hindlimb duplications were hypothesized to be caused by the formation of ectopic posterior body axes. For forelimb ectrodactyly, a locus on chromosome 11, Rafar, has linkage to the strain difference, and mRNA localization has shown that specific genes (Fgf8, Dlx3, Bmp4, and Sp8) in the postaxial preAER (prior to formation of the apical ectodermal ridge) of the developing limb bud (the site of the defect) were downregulated hours after atRA administration more in the susceptible C57 than in the SWV strain. Because both atRA and divalent cadmium induce postaxial forelimb ectrodactyly (right-sided predominance) at a high rate in C57BL/6 and low in the SWV strain, there is debate as to whether they share a common mechanism. These teratogens cause a greater-than-additive level of forelimb ectrodactyly when coadministered at low doses, but cadmium does not induce ectopic hindlimb formation. The hypothesis is that these agents have separate molecular pathologic pathways that converge to perturb a common anatomic structure.

Prenatal sonographic findings in a fetus with splenogonadal fusion limb defect syndrome.

Splenogonadal fusion limb defect syndrome (SGFLD) is a very rare abnormality. We report on a case with prenatal sonographic findings of a fetus with postnatally diagnosed SGFLD syndrome. This is also the second case of prenatal ultrasonographic diagnosis of gastrointestinal malrotation associated with SGFLD. A 26-year-old primigravid woman was referred to our clinic because of nonvisualization of both fetal femoral bones at 20 weeks of gestation. A detailed sonographic examination showed complete bilateral absence of lower limbs, micrognathia, single umbilical artery and a right-sided stomach. Autopsy confirmed prenatal sonographic findings and additionally showed that the spleen was abnormally connected to the left gonad by a fibrous band. In conclusion, although all limbs and both sides were equally affected in most of the reported cases, SGFLD syndrome should be considered in cases with terminal limb defects of lower limbs.

Caudal dysgenesis, sirenomelia, and situs inversus totalis: a primitive defect in blastogenesis.

Caudal dysgenesis (CD) constitutes a heterogeneous spectrum of congenital caudal anomalies, including varying degrees of agenesis of the vertebral column, as well as anorectal and genitourinary anomalies. Sirenomelia, characterized by a fusion of the lower limbs, could represent the most severe end of this spectrum. The two main debated pathogenic hypotheses are an aberrant vascular supply versus a primary axial mesoderm defect. We present the autopsy findings of two fetuses of non-diabetic mothers, with normal karyotype. Both fetuses presented situs inversus associated with a CD, in one case consisting of sirenomelia, establishing a very rare association profile that might be random. This association also suggests the occurrence of a common pathogenic mechanism, in accordance to recent genetic data, such as displayed in the Kif3A murine mutation phenotype. Some cases of sirenomelia and CD could represent developmental field defects of blastogenesis involving the caudal mesoderm, rather than being related to vascular insufficiency.

Sirenomelia: a case report.

Sirenomelia is a rare and interesting congenital anomaly where there is fusion of the lower limb buds in association with a number of other anomalies, together termed as the caudal regression syndrome. We report this syndrome in a male foetus of 33 weeks gestational age, and review its embryological basis.

Sirenomelia of an intracytoplasmic sperm injection conceptus: a case report and review of mechanism.

Postmortem dissection of the 18-week male conceptus, product of intracytoplasmic sperm injection (ICSI), demonstrated the hallmark findings of sirenomelia. The lower legs were fused and the left knee was rotated medially. Internal organs showed hypoplastic lungs, a multicystic kidney, and unilateral ureteral hypoplasia. The vitelline artery was absorbed, in a classic fashion, into the umbilical artery and communicated with the aorta at a point proximal to the iliac arteries. The tributaries distal to this point were hypoplastic. This finding is consistent with previously documented cases of sirenomelia and is thought to be the pathogenetic mechanism resulting in a vascular steal from the lower extremities. A rare finding was the presence of a penis on the dorsal side just below a perforate anus. In this case report, we discuss the pertinent clinical history and autopsy findings. A brief review of the mechanism thought to give rise to sirenomelia is provided. To our knowledge, this is the first reported case of sirenomelia in an ICSI conceptus.

Sirenomelia with agenesis of corpus callosum.

Sirenomelia is a very rare anomaly presented with fusion of the lower limbs. Genitourinary, neural tube, and vertebral anomalies are found in most cases. We report a case of sirenomelia with agenesis of corpus callosum, which has not been reported previously.