Heterogeneity in Roberts syndrome

Roberts syndrome with tetraphocomelia: A case report and literature review

Roberts syndrome is a rare genetic disorder characterized by symmetrical reductive limb malformation and craniofacial abnormalities. It is caused by mutation in the “Establishment of cohesion 1 homolog 2” genes, resulting in the loss of acetyltransferase activities and manifesting as premature centromere separation in metaphase chromosomes. The affected individual grows slowly during pregnancy and after birth with associated mild to severe intellectual impairment. We present a 35-year-old multiparous Nigerian lady who had emergency cesarean section at 35 weeks of gestation following abruptio placentae with a live fetus. The baby had poor Apgar score at birth and died shortly afterward. Tetraphocomelia was detected on prenatal ultrasound done at about 24 weeks of gestation with other features sonographically normal. However, clinical diagnosis of severe variant of Roberts syndrome with tetraphocomelia, growth restriction, and craniofacial abnormalities were noted at birth. This case exhibits a very rare variant of Roberts syndrome with tetraphocomelia, intrauterine growth restriction, and craniofacial abnormalities. It also highlights the crucial role of detailed clinical examination and the inherent challenges in making cytogenetic diagnosis in low-income countries.

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.

Femoral-tibial-synostosis in a child with Roberts syndrome (Pseudothalidomide): a case report

Background

Roberts syndrome (Pseudothalidomide) is a rare birth defect that causes severe bone malformation complex. The bones of the arms, and in some cases other appendages, may be extremely shortened and even absent. The fingers of the hands may be fused. An extreme case results in the absence of the upper bones of both the arms and legs so that the hands and feet appear attached directly to the body. This is called tetraphocomelia.

Case presentation

We report on a two-year-old boy of Austrian origin who manifests a constellation of malformation complex include prenatal and postnatal growth retardation, craniofacial anomalies and defective development of all four extremities. The overall clinico-radiographic features were compatible with Roberts syndrome (Pseudothalidomide). Significant unilateral femoral-tibial synostosis was additional malformation.

Conclusion

Associated malformations and symptoms may be the key factor in the differential diagnosis of neonatal malformation complex. Roberts's syndrome may be genetically transmitted within families as an autosomal recessive trait or may be the result of spontaneous/sporadic changes in the gene. Because the signs of the disorder so closely mimic those caused by the ingestion of thalidomide, the term "pseudo-thalidomide" is frequently used.

In this report we describe total femorotibial fusion in a child manifesting the phenotypic features consistent with Roberts syndrome from a healthy parents but first cousins in Austria. Aggressive medical intervention is of prime importance, as is forthright parental counselling when discussing the possible outcome for these patients.

Thrombocytopenia-absent radius syndrome: a clinical genetic study

The thrombocytopenia-absent radius (TAR) syndrome is a congenital malformation syndrome characterised by bilateral absence of the radii and a thrombocytopenia. The lower limbs, gastrointestinal, cardiovascular, and other systems may also be involved. Shaw and Oliver in 1959 were the first to describe this condition, but it was Hall et al in 1969 who reported the first major series of patients. Since then most reports have been based on single or small numbers of cases. We report the results of a clinical study looking at the phenotype of 34 patients with TAR syndrome. All cases had a documented thrombocytopenia and bilateral radial aplasia, 47% had lower limb anomalies, 47% cow's milk intolerance, 23% renal anomalies, and 15% cardiac anomalies. Congenital anomalies not previously described in association with TAR syndrome included facial capillary haemangiomata, intracranial vascular malformation, sensorineural hearing loss, and scoliosis. Karyotype analysis, chromosome breakage studies including premature centromeric separation and fluorescence in situ hybridisation studies looking for a deletion of chromosome 22q11 were undertaken. Two abnormal karyotypes were identified.

MCA syndrome with renal-hepatic-pancreatic dysplasia, posterior fossa cyst, symmetrical limb deficiencies, cleft palate, cardiac and Müllerian duct anomalies

We report the second trimester prenatal diagnosis of severe symmetrical limb deficiencies with posterior fossa cyst and cardiac anomaly in a female fetus. Fetopathological examination revealed additional anomalies: renal-hepatic-pancreatic dysplasia, cleft palate, and Müllerian duct anomaly. The spectrum of congenital malformations in the present observation is difficult to classify into a single syndrome entity and presents an overlap with several syndromes: Roberts syndrome, Goldston syndrome, and renal-hepatic-pancreatic dysplasia.

Novel assay for Roberts syndrome assigns variable phenotypes to one complementation group

Roberts syndrome (RS) is a rare autosomal recessive disorder characterized by heterogeneous clinical features, the most notable being tetraphocomelia, cleft lip, and cleft palate. Cells derived from most RS patients exhibit abnormal cytogenetic and cellular phenotypes that include the premature separation of para- and pericentromeric heterochromatin visible on C-banded metaphase chromosomes, a phenomenon referred to as heterochromatic splaying. Previously, it was shown that these abnormal phenotypes can be complemented following somatic cell hybridization between RS cells and control cells. In the current study, a permanent cell line was established from a new RS patient with a more severe phenotype than represented by previously established cells in culture. With a newly developed assay designed to facilitate rapid evaluation of in vitro complementation, we assigned this new patient to the same genetic complementation group defined by other, less severely affected patients. The results demonstrate that a single complementation group defines RS patients with heterochromatic splaying regardless of clinical severity.

Tetraphocomelia and bilateral cleft lip in a historical case of Roberts syndrome [Virchow, 1898]

We discuss an unlabelled specimen of tetraphocomelia and bilaterally cleft lip from the former Virchow Museum of our Medical School. Identity of the subject with a case of what was later termed "Roberts syndrome" published by Rudolf Virchow in 1898 is demonstrated. Rediscovery of this important historical case is gratifying, since almost 95% of the specimens of Virchow's collection were lost during World War II. We have restudied Virchow's case. Recent CT scan images of the fetus are presented. We review data from the literature and present new clinical details. The fate of the original clinical data after passing through three reviews is documented briefly. We also reconstruct Virchow's view on phocomelia and its consequences for later research.

Tetra-amelia and splenogonadal fusion in Roberts syndrome

Roberts-SC phocomelia syndrome comprises limb deficiencies of variable severity, facial clefts, and other anomalies. Tetra-amelia may also be associated with facial clefts and similar anomalies. We report on a female infant with severe tetra-amelia, micrognathia, cleft palate, splenogonadal fusion, and premature centromere separation. We propose that this represents the severe expression of the Roberts-SC phocomelia syndrome.

Roberts syndrome fibroblasts showing cisplatin hypersensitivity have normal host cell reactivation of cisplatin-treated adenovirus and normal capacity of cisplatin-treated cells for adenovirus DNA synthesis

Roberts syndrome (RS) is a rare, recessively inherited disorder characterized by growth retardation, limb reductions and craniofacial deformities. Cells from a subset of afflicted individuals, termed RS+, display unusual separation or puffing of the heterochromatic regions of their chromosomes and are hypersensitive to several DNA-damaging agents including mitomycin C (MMC) and cisplatin, both of which can induce interstrand crosslinks in DNA. For this reason, we have investigated the ability of RS+ fibroblasts to repair cisplatin-induced DNA lesions using adenoviris as a probe. Host cell reactivation of cisplatin-treated adenovirus (Ad) was significantly reduced in nucleotide excision repair (NER)-deficient xeroderma pigmentosum (XP) cells but was normal in the two RS+ fibroblast strains and the Fanconi's anemia (FA)fibroblast strain tested. The capacity of cisplatin-treated cells for Ad DNA synthesis was reduced in XP and FA cells compared to normal human cells, but was not reduced in RS+ cells. These results indicate that the hypersensitivity of RS+ cells to cisplatin is not due to a deficiency in NER nor due to a deficiency in the pathway which leads to cisplatin hypersensitivity in FA cells. It is possible that the abnormal heterochromatin organisation of RS+ cells selectively renders the heterochromatic regions of the genome more susceptible to mutagen damage and/or less available for repair.

Objective analysis of centromere separation

Centromere separation sequence and premature centromere division have gained increasing interest; however, inaccuracy and subjectivity in their investigation have often been criticized. We describe a simple computerized image analysis system that makes an objective and exact staging of centromere division possible.