Incidental detection of premature centromere separation in amniocytes associated with a mild form of Roberts syndrome

Long-term survival after corrective surgeries in two patients with severe deformities due to Roberts syndrome: A Case report and review of the literature

Roberts syndrome (RBS; OMIM 268300) is a rare autosomal recessive disease characterized by retardation before and after birth, cranial and maxillofacial deformities, limb anomalies and intellectual disability. Mutations in the establishment of cohesion 1 homologue 2 (ESCO2) gene on chromosome 8p21.1 have been found to be causative for RBS. We describe two patients with RBS with physical deformities and ll. One is an 8-year-old Yemeni male, and the other is his 13-year-old sister. These patients were diagnosed with RBS and underwent surgeries during their first to third years of life. Here, we present the cases for the two patients, focusing specifically on their surgical management and outcomes. Additionally, by reviewing the literature on RBS, we also summarize the proper surgical interventions for this rare disease. This paper describes the long-term follow-up of two patients with severe deformities who benefitted from corrective surgeries. The findings of this study indicate that patients who survive infancy and reach adulthood, even patients who present with severe disease symptoms, can benefit from corrective surgeries and lead better lives.

Roberts-SC phocomelia syndrome

A severely growth retarded baby was born at 38 weeks gestation. He had multiple craniofacial anomalies, microbrachycephaly, phocomelia in the upper limbs and renal cysts visible on ultrasound. He died of recurrent apneas. The autopsy showed left sided multicystic dysplastic kidney and absence of one testis. Cytogenetic studies did not reveal any abnormality. The phenotypic features match those described in the Roberts-SC phocomelia syndrome. A literature review revealed that 50% of these patients have chromosomal defects and antenatal detection is possible on ultrasound and by chromosome analysis of the amniocytes.

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.

Prenatal diagnosis of Roberts syndrome: two new cases

We report two fetuses with typical anomalies of Roberts syndrome. Prenatal diagnosis was confirmed by the characteristic disjunction of centromeres in amniocytes. We compare these cases with a child who presented with severe Roberts syndrome. We attempted to evaluate quantitatively the centromeric abnormality and the chromosome separation in the different cultures and with different methods. The variability of the clinical manifestations and cytogenetic investigations of this syndrome are reviewed.

Heterogeneity in Roberts syndrome

Roberts syndrome (RS) is a rare, autosomal recessive condition characterized primarily by growth retardation, developmental delay, and limb anomalies. Some RS patients (RS+), but not others (RS-), have an abnormality of their constitutive heterochromatin (the "RS effect"). RS+ patients also show a cellular hypersensitivity to DNA damaging agents such as mitomycin C (MMC). Lymphoblastoid cell lines from 2 unrelated RS+ patients were fused and hybrid cells examined for correction of the RS effect and MMC hypersensitivity. Neither cellular defect was corrected in the 2 hybrid cell lines examined, suggesting that these 2 patients represent a single complementation group. Fusions were also performed between one RS+ cell line and 2 different RS- cell lines. In both fusions, the hybrids demonstrated correction of both the heterochromatin abnormality and MMC hypersensitivity. These observations suggest that RS+ and RS- patients belong to different complementation groups and do not arise from the same single gene mutation.

Roberts syndrome: a review of 100 cases and a new rating system for severity

Roberts syndrome (RS) is a rare genetic disorder characterized by pre- and postnatal growth retardation, limb defects, and craniofacial anomalies. Affected persons have varying degrees of malformations involving symmetric reduction in the number of digits, and length or presence of bones in the arms and legs. Craniofacial malformations involve hypertelorism, hypoplastic nasal alae, and a high incidence of cleft lip and palate. Familial and sporadic cases have been reported consistent with an autosomal recessive mode of inheritance. Mitotic cells from many individuals with RS display a characteristic cytogenetic phenomenon consisting of repulsion of heterochromatic regions near centromeres, particularly of chromosomes 1, 9, 16, and splaying of the short arms of the acrocentrics and of the distal Yq. Mitosis in RS cells is abnormal in metaphase duration and anaphase progression. Specifically, anaphase figures show a higher degree of chromosomes that are outlying, lagging, or prematurely advancing toward the poles compared to normal controls. RS cells have abnormal nuclear morphology and also show a higher frequency of micronucleation than normal cells, presumably as a result of the abnormal mitotic events during anaphase. Therefore, RS has been interpreted as a human mitotic mutation syndrome which leads to secondary developmental defects. This report reviews 100 cases of RS, summarizes the phenotypic, genetic, cytogenetic, and cell biology findings in Roberts syndrome, and introduces the RS Rating for quantitating severity.

Roberts/pseudothalidomide syndrome and normal intelligence: approaches to diagnosis and management

Roberts/pseudothalidomide syndrome is a rare autosomal recessive disorder, involving growth and mental retardation, midline craniofacial abnormalities and tetraphocomelia. Cytogenetic studies have confirmed reproducible chromosomal abnormalities throughout the syndrome's wide range of clinical presentations. A family with two affected siblings is presented. One child was stillborn; the other, though severely affected by all of the physical characteristics of this disorder, has developed normally both at school and in his social-personal skills. This report supports the idea that Roberts syndrome and pseudothalidomide syndrome are the same condition, and emphasizes that normal intelligence and positive social-personal adjustment are possible, even with all of the stigmata of Roberts syndrome. Aggressive medical intervention is suggested, as well as forthright parental counselling when discussing the possible outcome for these patients.

First-trimester prenatal diagnosis of Roberts syndrome

We present a case of prenatal detection of premature centromere separation on chorionic villi sampled at 8 weeks' gestation from a woman at risk of recurrence of Roberts syndrome. The same cytogenetic characteristic was confirmed on amniocytes at 14 weeks when ultrasound examination showed morphological anomalies of the fetus. To our knowledge, this is the first report of early prenatal diagnosis of Roberts syndrome.

Studies of mitotic and centromeric abnormalities in Roberts syndrome: implications for a defect in the mitotic mechanism

Roberts syndrome is an inherited human condition that is of particular interest because separation of centromeres and constitutive heterochromatin is observed in metaphase chromosomes. In this study we investigated the frequency of other cytological abnormalities in three Roberts syndrome patients. Our findings when taken with previous cytological reports emphasize that there are other features that are equally characteristic of Roberts syndrome: (1) aneuploidy with random chromosome loss and (2) micronuclei and/or nuclear lobulations of 8%-24% of interphase cells. We observed abnormal chromosome movement involving one or all the chromosomes during anaphase. Evidence is presented suggesting that aneuploidy, micronuclei and abnormal nuclear morphology are a direct result of lagging chromosomes. The cytological features documented for Roberts syndrome indicate that this is a human mitotic mutant.

The Baller-Gerold syndrome: phenotypic and cytogenetic overlap with Roberts syndrome

A case is reported where the major clinical features of craniostenosis and radial aplasia led to an initial diagnosis of Baller-Gerold syndrome. Mild fibular hypoplasia on skeletal survey led to review of the diagnosis and the similarity of the facial phenotype to that of Roberts syndrome was noted. Chromosome analysis showed the premature centromere separation characteristic of this condition. This case raises the question as to whether the Baller-Gerold syndrome can be considered as a distinct entity. It is suggested that cases diagnosed as having Baller-Gerold syndrome should have cytogenetic analysis and that known Roberts syndrome survivors are reviewed for signs of craniostenosis.

Mitotic disturbance associated with mosaic aneuploidies

The association of various unsystematic aneuploidies with premature centromere division (PCD) was observed in a patient with conspicuous clinical features and combined immunodeficiency. Trisomies and monosomies of almost all autosomes and gonosomal aberrations were found separately or in combination in a majority of the proband's lymphocytes and fibroblasts. The chromosome number varied from 44 to 50. A high proportion of the metaphases showed PCD or had the appearance of C-anaphases. These findings probably represent a new mutant affecting mitosis and causing mosaic aneuploidies.