Sirenomelia: An anatomical assessment and genetic sex determination of two cases.

The etiology of sirenomelia is currently unknown. Data are limited in comparing external and internal abnormalities using modern imaging technologies and molecular genetic analysis. The purpose of the current study was designed to compare external and internal anatomical defects in two cases of sirenomelia and Potter's sequence. Considered rare, Potter's sequence is a fetal disorder with characteristic features of bilateral renal agenesis, obstructive uropathy, atypical facial appearance, and limb malformations. The internal and external malformations of two term fetuses with sirenomelia and Potter's sequence were compared using assessment of external features, radiography and MRI on internal structures, and molecular genetic studies on sex determination. Data reveal that both fetuses were male and manifested with an overlapping but distinct spectrum of abnormalities. Principal differences were noted in the development of the ears, brain, urogenital system, lower limbs, pelvis, and vertebral column. Defects of the axial mesoderm are likely to underlie the abnormalities seen in both fetuses. The first one, which had only caudal defects, was found to have a spectrum of abnormalities most similar to those associated with more severe forms of the small pelvic outlet syndrome, although the structure and orientation of the sacrum and iliae were different from previously reported cases. The other had both caudal and cranial defects, and was most similar to those described in the axial mesodermal dysplasia syndrome. Defects associated with sirenomelia can be evaluated with standard gross anatomy examination, radiology, MRI, and modified PCR techniques to determine anatomical abnormalities and the sex of preserved specimens, respectively. Evidence indicated that sirenomelia could be developed via various etiologies.

Protetización temprana y seguimiento de paciente pediátrico con hemimelia tibial / Early Fitting and Follow-Up of A Pediatric Patient with Tibial Hemimelia

Introducción: La hemimelia tibial es una entidad poco frecuente, presente hasta en 1:1.000.000 nacidos vivos. Tiene una asociación genética autosómica recesiva, y se presenta con cambios en la morfología del miembro inferior con una tibia ausente o presente parcialmente, además de cambios en peroné, rodilla y pie. Según su clasificación se puede manejar con reconstrucción quirúrgica de la extremidad o amputación. La posibilidad de una prótesis temprana favorece el resultado funcional del paciente y su adaptación protésica. Objetivo: Presentar el caso de una entidad poco común tratada con desarticulación a nivel de la rodilla y prótesis por su grado de compromiso. Presentación de caso: Paciente femenina de tres años con compromiso del miembro inferior derecho. Los primeros años usó una prótesis artesanal fabricada por su familia. Fue valorada por la Junta Médica de rehabilitación y ortopedia que decidió intervención quirúrgica para desarticulación de la rodilla. Se realizó protetización temprana en busca de beneficios de cicatrización, control del edema y adaptación postquirúrgica. Se realizan controles posteriores con ajustes a la prótesis de acuerdo con las necesidades propias de la edad de la paciente. Conclusiones: Se muestra una adecuada evolución postquirúrgica, sin dolor o neuropatía, con un reinicio temprano de la marcha y progreso adecuado de su neurodesarrollo e integración social, lo que da una pauta de manejo en paciente pediátrico con este tipo de deformidades(AU)

Introduction: Tibial hemimelia is a rare entity, reported in up to 1:1,000,000 live births. It has an autosomal recessive genetic association, and it presents with changes in the morphology of the lower limb with an absent or partially present tibia, as well as changes in the fibula, knee, and foot. Depending on its classification, it can be managed with surgical reconstruction of the limb or amputation. The possibility of an early prosthesis favors the functional result of the patient and his prosthetic adaptation. Objective: To report the case of a rare entity treated with knee disarticulation and prosthesis due to its degree of compromise. Case report: The case of a three-year-old female patient with compromise of the lower right limb is reported here. The first years she used a handmade prosthesis made by her family. She was assessed by the Medical Board of Rehabilitation and Orthopedics, which decided to undergo surgery for knee disarticulation. Early fittings were performed in search of healing benefits, edema control and post-surgical adaptation. Subsequent controls were carried out with adjustments to the prosthesis according to the needs of the patient's age. Conclusions: An adequate post-surgical evolution is shown, without pain or neuropathy, with early resumption of gait and adequate progress of their neurodevelopment and social integration, which provides recommendation for management in pediatric patients with this type of deformity(AU)

Genetically induced redox stress occurs in a yeast model for Roberts syndrome.

Roberts syndrome (RBS) is a multispectrum developmental disorder characterized by severe limb, craniofacial, and organ abnormalities and often intellectual disabilities. The genetic basis of RBS is rooted in loss-of-function mutations in the essential N-acetyltransferase ESCO2 which is conserved from yeast (Eco1/Ctf7) to humans. ESCO2/Eco1 regulate many cellular processes that impact chromatin structure, chromosome transmission, gene expression, and repair of the genome. The etiology of RBS remains contentious with current models that include transcriptional dysregulation or mitotic failure. Here, we report evidence that supports an emerging model rooted in defective DNA damage responses. First, the results reveal that redox stress is elevated in both eco1 and cohesion factor Saccharomyces cerevisiae mutant cells. Second, we provide evidence that Eco1 and cohesion factors are required for the repair of oxidative DNA damage such that ECO1 and cohesin gene mutations result in reduced cell viability and hyperactivation of DNA damage checkpoints that occur in response to oxidative stress. Moreover, we show that mutation of ECO1 is solely sufficient to induce endogenous redox stress and sensitizes mutant cells to exogenous genotoxic challenges. Remarkably, antioxidant treatment desensitizes eco1 mutant cells to a range of DNA damaging agents, raising the possibility that modulating the cellular redox state may represent an important avenue of treatment for RBS and tumors that bear ESCO2 mutations.

Dichorionic twin pregnancy with sirenomelia and chromosomal anomaly in 1 fetus: A case report.

RATIONALE: Sirenomelia is a rare congenital malformation that threatens fetal survivals. The cases in which twin with sirenomelia and chromosomal abnormality have been seldomly reported. We reported a dichorionic twin case in which one twin had sirenomelia, the other twin had a normal phenotype, and they had different chromosomal abnormalities. PATIENT CONCERNS: The abnormal twin was found at 22 weeks by ultrasound. The sirenomelia fetus was complicated with a thoracic stenosis, enlarged rectum without anal opening, the absence of bilateral kidneys, a single umbilical artery, a single lower limb, the abnormal curvature of spine, double outlet of right ventricle, which were the indicatives of the chromosome detection. DIAGNOSIS: The copy number variation of the sirenomelia fetus was detected as a deletion of 4.8Mb in 11p11.12-11q11. The co-twin was found with del(Y)(q11.223q11.23), which was as the same as his father's. The mother had normal chromosome. The parents had normal phenotypes. It was firstly reported a microdeletion with sirenomelia fetus. INTERVENTIONS: There was no specific treatments for the twins. OUTCOMES: Intrauterine death of the sirenomelia fetus was found at 27 weeks and postnatal death after inevitable abortion happened to the co-twin. LESSONS: Prenatal ultrasound was responsible for recognizing sirenomelia, and the detailed ultrasound scanning and chromosome detection should be done for the co-twin. The etiology of sirenomelia remains unclear, and genetic detection is also necessary for its pathogenesis research.

Successful pregnancy outcome in two sisters with cerebral palsy and phocomelia: a case report and literature review.

BACKGROUND: Little is known about pregnancy rates and outcome in women with motoric disabilities like cerebral palsy (CP) and even less in phocomelia. OBJECTIVE: To show complications and psychosocial issues in relation to pregnancy burdened by impaired mobility in CP and phocomelia. CASE REPORT: We present an overview of the pregnancy outcome in two cases of sisters with cerebral palsy and phocomelia. We show complications and psychosocial issues in relation to pregnancy burdened by impaired mobility. Both sisters had a successful pregnancy outcome. CONCLUSION: There is a need to increase awareness, education, support, and advocacy in order to optimize pregnancy course and outcome in women with CP and phocomelia.

An ever-changing landscape in Roberts syndrome biology: Implications for macromolecular damage.

Roberts syndrome (RBS) is a rare developmental disorder that can include craniofacial abnormalities, limb malformations, missing digits, intellectual disabilities, stillbirth, and early mortality. The genetic basis for RBS is linked to autosomal recessive loss-of-function mutation of the establishment of cohesion (ESCO) 2 acetyltransferase. ESCO2 is an essential gene that targets the DNA-binding cohesin complex. ESCO2 acetylates alternate subunits of cohesin to orchestrate vital cellular processes that include sister chromatid cohesion, chromosome condensation, transcription, and DNA repair. Although significant advances were made over the last 20 years in our understanding of ESCO2 and cohesin biology, the molecular etiology of RBS remains ambiguous. In this review, we highlight current models of RBS and reflect on data that suggests a novel role for macromolecular damage in the molecular etiology of RBS.

Juberg-Hayward syndrome and Roberts syndrome are allelic, caused by mutations in ESCO2.

OBJECTIVE: Juberg-Hayward syndrome (JHS; MIM 216100) is a rare autosomal recessive malformation syndrome, characterized by cleft lip/palate, microcephaly, ptosis, hypoplasia or aplasia of thumbs, short stature, dislocation of radial head, and fusion of humerus and radius leading to elbow restriction. A homozygous mutation in ESCO2 has recently been reported to cause Juberg-Hayward syndrome. Our objective was to investigate the molecular etiology of Juberg-Hayward syndrome in two affected Lisu tribe brothers. MATERIALS AND METHODS: Two patients, the unaffected parents, and two unaffected siblings were studied. Clinical and radiographic examination, whole exome sequencing, Sanger sequencing, Western blot analysis, and chromosome testing were performed. RESULTS: Two affected brothers had characteristic features of Juberg-Hayward syndrome, except for the absence of microcephaly. The elder brother had bilateral cleft lip and palate, short stature, humeroradial synostosis, and simple partial seizure with secondary generalization. The younger brother had unilateral cleft lip and palate, short stature, and dislocation of radial heads. The homozygous (c.1654C > T; p.Arg552Ter) mutation in ESCO2 was identified in both patients. The other unaffected members of the family were heterozygous for the mutation. The presence of humeroradial synostosis and radial head dislocation in the same family is consistent with both being in the same spectrum of forearm malformations. Chromosome testing of the affected patients showed premature centromere separation. Western blot analysis showed reduced amount of truncated protein. CONCLUSION: Our findings confirm that a homozygous mutation in ESCO2 is the underlying cause of Juberg-Hayward syndrome. Microcephaly does not appear to be a consistent feature of the syndrome.

Roberts syndrome in an Indian patient with humeroradial synostosis, congenital elbow contractures and a novel homozygous splice variant in ESCO2.

Roberts syndrome (also known as Roberts-SC phocomelia syndrome) is an autosomal recessive developmental disorder, characterized by pre- and postnatal growth retardation, limb malformations including bilateral symmetric tetraphocomelia or mesomelia, and craniofacial dysmorphism. Biallelic loss-of-function variants in ESCO2, which codes for establishment of sister chromatid cohesion N-acetyltransferase 2, cause Roberts syndrome. Phenotypic spectrum among patients is broad, challenging clinical diagnosis in mildly affected individuals. Here we report a 3-year-old boy with a mild phenotype of Roberts syndrome with bilateral elbow contractures, humeroradial synostosis, mild lower limb disparity, and facial dysmorphism. Trio whole-exome sequencing identified the novel biallelic splice variant c.1673+1G>A in ESCO2 in the patient. Aberrant ESCO2 pre-mRNA splicing, reduced relative ESCO2 mRNA amount, and characteristic cytogenetic defects, such as premature centromere separation, heterochromatin repulsion, and chromosome breaks, in patient cells strongly supported pathogenicity of the ESCO2 variant affecting one of the highly conserved guanine-thymine dinucleotide of the donor splice site. Our case highlights the difficulty in establishing a clinical diagnosis in individuals with minor clinical features of Roberts syndrome and normal intellectual and social development. However, next-generation sequencing tools allow for molecular diagnosis in cases presenting with mild developmental defects.

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.

Exome sequencing identifies the first genetic determinants of sirenomelia in humans.

Sirenomelia is a rare severe malformation sequence of unknown cause characterized by fused legs and severe visceral abnormalities. We present a series of nine families including two rare familial aggregations of sirenomelia investigated by a trio-based exome sequencing strategy. This approach identified CDX2 variants in the two familial aggregations, both fitting an autosomal dominant pattern of inheritance with variable expressivity. CDX2 is a major regulator of caudal development in vertebrate and mouse heterozygotes are a previously described model of sirenomelia. Remarkably, the p.(Arg237His) variant has already been reported in a patient with persistent cloaca. Analysis of the sporadic cases revealed six additional candidate variants including a de novo frameshift variant in the genetically constrained NKD1 gene, encoding a known interactor of CDX2. We provide the first insights for a genetic contribution in human sirenomelia and highlight the role of Cdx and Wnt signaling pathways in the development of this disorder.

Non-redundant roles in sister chromatid cohesion of the DNA helicase DDX11 and the SMC3 acetyl transferases ESCO1 and ESCO2.

In a process linked to DNA replication, duplicated chromosomes are entrapped in large, circular cohesin complexes and functional sister chromatid cohesion (SCC) is established by acetylation of the SMC3 cohesin subunit. Roberts Syndrome (RBS) and Warsaw Breakage Syndrome (WABS) are rare human developmental syndromes that are characterized by defective SCC. RBS is caused by mutations in the SMC3 acetyltransferase ESCO2, whereas mutations in the DNA helicase DDX11 lead to WABS. We found that WABS-derived cells predominantly rely on ESCO2, not ESCO1, for residual SCC, growth and survival. Reciprocally, RBS-derived cells depend on DDX11 to maintain low levels of SCC. Synthetic lethality between DDX11 and ESCO2 correlated with a prolonged delay in mitosis, and was rescued by knockdown of the cohesin remover WAPL. Rescue experiments using human or mouse cDNAs revealed that DDX11, ESCO1 and ESCO2 act on different but related aspects of SCC establishment. Furthermore, a DNA binding DDX11 mutant failed to correct SCC in WABS cells and DDX11 deficiency reduced replication fork speed. We propose that DDX11, ESCO1 and ESCO2 control different fractions of cohesin that are spatially and mechanistically separated.

The role of ESCO2, SALL4 and TBX5 genes in the susceptibility to thalidomide teratogenesis.

Thalidomide is widely used for several diseases; however, it causes malformations in embryos exposed during pregnancy. The complete understanding of the mechanisms by which thalidomide affects the embryo development has not yet been obtained. The phenotypic similarity makes TE a phenocopy of syndromes caused by mutations in ESCO2, SALL4 and TBX5 genes. Recently, SALL4 and TBX5 were demonstrated to be thalidomide targets. To understand if these genes act in the TE development, we sequenced them in 27 individuals with TE; we verified how thalidomide affect them in human pluripotent stem cells (hPSCs) through a differential gene expression (DGE) analysis from GSE63935; and we evaluated how these genes are functionally related through an interaction network analysis. We identified 8 variants in ESCO2, 15 in SALL4 and 15 in TBX5. We compared allelic frequencies with data from ExAC, 1000 Genomes and ABraOM databases; eight variants were significantly different (p < 0.05). Eleven variants in SALL4 and TBX5 were previously associated with cardiac diseases or malformations; however, in TE sample there was no association. Variant effect prediction tools showed 97% of the variants with potential to influence in these genes regulation. DGE analysis showed a significant reduction of ESCO2 in hPSCs after thalidomide exposure.

Clinical spectrum of congenital tibial hemimelia in 35 limbs of 24 patients: A single center observational study from India.

PURPOSE: Considering the paucity of reports on large series of patients with tibial hemimelia, we assessed the clinical spectrum of this rare congenital disorder in patients seen at a single Indian center over 10 years. METHODS: Retrospective review of medical records of patients seen at single center in 10 years. RESULTS: Thirty-five cases of TH, mostly Jones types Ia (18) and II (10), were diagnosed in 24 patients (13 had unilateral TH). Associated foot deformities included equinovarus (22), varus foot (10), absence of the medial row of toes (5) and polydactyly (3). Upper limbs anomalies included split-hand deformity (five patients) and radial club hand (two patients). Nine limbs of seven patients were surgically reconstructed. Modified orthosis was provided to seven patients, custom designed prosthesis fitment in six and amputation with prosthesis fitment in one. Patients presenting at adolescence or later were habituated to their deformity for indoor ambulation; families declined amputation. CONCLUSION: Reports of more TH cases will provide input to researchers to consider comprehensive rehabilitation for enhancing indoor and community ambulation.

Effects of the Y-chromosome and the dominant hemimelia mutation on the morphology of the mouse mandible.

The aims of this study were to test whether the Y-chromosome and the autosomal dominant hemimelia (Dh) mutation can affect mandible morphology in mice. I analyzed mandible size and shape using landmark-based geometric morphometrics in 16 DH-Chr Y@ -+/+ (@ represents one of the inbred strain names) strains and observed significant differences in mandible size. The largest mandible was identified in strain DH-Chr YC3H and the smallest in strain DH-Chr YKK . Canonical variate and discriminant function analyses suggested that the mandible shapes of strains DH-Chr YC3H and DH-Chr YKK differed from those of the other strains. Because seven of the DH-Chr Y@ -+/+ strains were maintained with dominant hemimelia, I also analyzed the potential influence of dominant hemimelia on mandible morphology because dominant hemimelia is known to cause various skeletal malformations. There were no significant differences in mandible size in seven sets of DH-Chr Y@ -+/+ and DH-Chr Y@ -Dh/+ strains. However, canonical variate analysis mapped strains DH-Chr YCAS -Dh/+ and DH-Chr YCBA -Dh/+ mapped distantly from the rest. Additionally, I observed similar patterns of shape change between DH-Chr YCAS -+/+ and DH-Chr YCAS -Dh/+, and between DH-Chr YCBA -+/+ and DH-Chr YCBA -Dh/+. These data indicate that the Y-chromosome affects the size and shape of the mouse mandible. Dominant hemimelia affects mandible shape but not size, and its effects emerge depending on the kinds of Y-chromosomes.

A Roberts Syndrome Individual With Differential Genotoxin Sensitivity and a DNA Damage Response Defect.

PURPOSE: Roberts syndrome (RBS) is a rare, recessively transmitted developmental disorder characterized by growth retardation, craniofacial abnormalities, and truncation of limbs. All affected individuals to date have mutations in the ESCO2 (establishment of cohesion 2) gene, a key regulator of the cohesin complex, which is involved in sister chromatid cohesion and DNA double-strand break (DSB) repair. Here we characterize DNA damage responses (DDRs) for the first time in an RBS-affected family. METHODS AND MATERIALS: Lymphoblastoid cell lines were established from an RBS family, including the proband and parents carrying ESCO2 mutations. Various DDR assays were performed on these cells, including cell survival, chromosome break, and apoptosis assays; checkpoint activation indicators; and measures of DNA breakage and repair. RESULTS: Cells derived from the RBS-affected individual showed sensitivity to ionizing radiation (IR) and mitomycin C-induced DNA damage. In this ESCO2 compound heterozygote, other DDRs were also defective, including enhanced IR-induced clastogenicity and apoptosis; increased DNA DSB induction; and a reduced capacity for repairing IR-induced DNA DSBs, as measured by γ-H2AX foci and the comet assay. CONCLUSIONS: In addition to its developmental features, RBS can be, like ataxia telangiectasia, considered a DDR-defective syndrome, which contributes to its cellular, molecular, and clinical phenotype.

Hypopigmented patches in Roberts/SC phocomelia syndrome occur via aneuploidy susceptibility.

Roberts/SC phocomelia syndrome (RBS/SC) is a rare autosomal recessive inherited condition characterized by prenatal-onset growth retardation, craniofacial anomalies, and symmetrical limb reduction defects. Here, we present two affected siblings with RBS/SC who have consanguineous parents. Both patients had intrauterine growth retardation; similar facial findings, including arched eyebrows, epicanthic folds, posteriorly angulated ears, and retrognathia; and hypopigmented patches on their skin. However, despite these common findings, the extremity involvement was different between the patients. The more severely affected boy had hypoplasia of the tibia and symmetrical agenesis of the radius, ulna, proximal carpal bones, and fibula. The slightly affected girl presented with mild symmetrical mesomelic shortening. The cytogenetic analysis showed aneuploidies at varying rates concerning different chromosomes in the analyses of different culture materials. As a remarkable finding in the cytogenetic studies, chromosome analysis of fibroblast cultures obtained from the hypopigmented skin region showed a much higher frequency of aneuploidy, especially trisomy 7, than normopigmented skin fibroblasts and lymphocyte cultures for both patients, which was also proven ex vivo by qPCR analyses from uncultured skin tissues. In the subsequent ESCO2 gene sequence analysis, both patients were found to be homozygous for the mutation c.1111dupA (p.Thr371Asnfs*32; NM_001017420.2), which is known to be pathogenic. In the literature search, only two RBS/SC patient reports with hypopigmented skin patches could be found. In addition, the presence of pigmentation defects in the embryo was reported in some different animal models for RBS/SC. When the literature review and study are evaluated together, hypopigmented patches can be considered as a rare finding for RBS/SC. It can be suggested that somatic aneuploidies seen in the natural course of the disease, especially aneuploidy of chromosome 7, which has many genes associated with pigmentation, may be responsible for the hypopigmentation patches.

A Novel Frameshift Mutation in ESCO2 Gene in Roberts Syndrome.

Roberts syndrome is a very rare autosomal recessive inheritance pattern genetic disorder characterised by symmetric bilateral extremity deformities, midfacial defect, and severe intellectual deficit. These patients also grow slowly prenatal and postnatal. RBS is caused by mutation in the ESCO2 gene. With these clinical and radiological findings, the case was diagnosed as Roberts syndrome. Full gene sequencing of the ESCO2 gene for the patient was done. In this patient, a novel frameshift mutation was identified in the ESCO2 gene.