Four siblings with Robert's syndrome

A review of supernumerary and absent limbs and digits of the upper limb

For years people have been enamored by anomalies of the human limbs, particularly supernumerary and absent limbs and digits. Historically, there are a number of examples of such anomalies, including royal families of ancient Chaldea, tribes from Arabia, and examples from across nineteenth century Europe. The development of the upper limbs in a growing embryo is still being elucidated with the recent advent of homeobox genes, but researchers agree that upper limbs develop between stages 12-23 through a complex embryological process. Maternal thalidomide intake during limb development is known to cause limb reduction and subsequent amelia or phocomelia. Additionally, a number of clinical reports have illustrated different limb anomaly cases, with each situation unique in phenotype and developmental abnormality. Supernumerary and absent limbs and digits are not unique to humans, and a number of animal cases have also been reported. This review of the literature illustrates the historical, anatomical, and clinical aspects of supernumerary and absent limbs and digits for the upper limb.

Roberts-SC syndrome, a rare syndrome and cleft palate repair

Roberts SC syndrome is a rare syndrome with only 17 previously recognized patients reported in medical literature. The syndrome is characterized by multiple malformations, particularly, symmetrical limb reduction, craniofacial anomalies such as bilateral cleft lip and palate, micrognathia, and severe growth and mental retardation. Our patient, a young child of five years having Roberts-SC, was successfully operated for cleft palate under general anesthesia. The main features of the syndrome and the technical problems of anesthesia and surgery are discussed in this report.

Vascular malformations. Part II: associated syndromes

Cutaneous vascular malformations are rare disorders representing errors in vascular development. These lesions occur much less commonly but are often confused with the common infantile hemangioma. It is important to properly diagnose vascular malformations because of their distinct differences in morbidity, prognosis and treatment. Vascular malformations may be associated with underlying disease or systemic anomalies. Several of these syndromes are well defined and can often be distinguished on the basis of the flow characteristics of the associated vascular malformation.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be able to better recognize underlying diseases or systemic anomalies that may be associated with vascular malformations. Participants should also better understand the various syndromes and conditions discussed and become more familiar with their management.

Mapping of a single locus capable of complementing the defective heterochromatin phenotype of Roberts syndrome cells

Roberts syndrome (RS) is a developmental disorder characterized by tetraphocomelia and a broad spectrum of additional clinical features. Most patients with RS exhibit characteristic cytogenetic phenotypes, which include an abnormal appearance of pericentromeric heterochromatin on metaphase chromosomes, referred to as "heterochromatic repulsion." In the present study, we use complementation of this abnormal cytogenetic phenotype as a means to identify a specific region of the normal human genome capable of rendering phenotypic correction. We screened the entire human genome, using a transient chromosome-transfer assay, and demonstrated complementation exclusively after the transfer of proximal chromosome 8p, a result subsequently confirmed by stable microcell-mediated chromosome transfer. Additionally, homozygosity mapping was used to refine the interval of this complementing locus to 8p21. The results are consistent with the notion that the single gene defect responsible for heterochromatic splaying and developmental abnormalities maps to chromosome 8p21.

Bilaterally cleft lip, limb defects, and haematological manifestations: Roberts syndrome versus TAR syndrome

We report on a 13-year-old patient followed since birth. He is the only offspring of young, non-consanguineous German parents. His mother has an isolated left cleft of lip and a cleft palate. At birth, our patient presented with bilaterally cleft lip/cleft palate, phocomelia of upper limbs with normal hands, and mild symmetrical deficiencies of the long bones of the lower limbs. Haematological evaluation demonstrated a leukaemoid reaction during a urinary tract infection as well as intermittent thrombocytopenia and episodes of marked eosinophilia during the first two years of life. Intellectual development has been normal. Comparison with two similar cases from the literature suggests a non-random phenotypic overlap of Roberts syndrome (MIM 268300) and TAR syndrome (MIM 274000). Such clinical constellations may be key observations to understand the genetic relationship of Roberts syndrome and TAR syndrome in future phenotype-genotype correlations.

A mild form of Roberts/SC phocomelia syndrome with asymmetrical reduction of the upper limbs

Roberts syndrome is a rare autosomal recessive condition characterized by growth retardation, cranio-facial abnormalities and symmetrical limb reduction of variable severity. Most patients with Roberts syndrome show a typical cytogenetic finding known as "Roberts syndrome effect". We describe a 4-month-old patient with a mild form of this syndrome, who presented with an asymmetrical reduction of the right upper limb.

Tetra-amelia, lung hypo-/aplasia, cleft lip-palate, and heart defect: a new syndrome?

We report on a family with two sons affected with tetra-amelia, cleft lip-palate, bilateral agenesis of lungs, and heart defects. These two cases support the previous suggestions that this complex entity may indeed represent a new syndrome. However, the mode of inheritance is still not clarified.

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.

Recurrent tetraamelia and pulmonary hypoplasia with multiple malformations in sibs

A term amelic female infant was born to an apparently nonconsanguineous Arab Moslem couple. This was followed by the birth of 4 normal children. Afterwards, in 2 subsequent pregnancies, 2 amelic fetuses were diagnosed by transabdominal ultrasonography in the 18th and 12th week of gestation. Pregnancies were terminated and on autopsy both amelic fetuses had severe lung hypoplasia and aplasia of the peripheral pulmonary vessels. The first fetus also had apparently low-set ears and micrognathia, whereas the last had hydrocephaly and left cleft lip beside the lung hypoplasia and aberrant pulmonary artery. This appears to be a new autosomal recessive malformation syndrome.

Roberts syndrome or "X-linked amelia"?

We report on a syndrome of tetra-amelia, facial clefts, absence of ears, nose, and atresia ani, affecting 7 male infants or fetuses in one Arab Moslem kindred. The combination of anomalies described in each affected member is consistent with Roberts syndrome and the prevalence of intermarriage in this kindred could suggest an autosomal recessive mode of inheritance. Alternatively, the existence of a new syndrome, namely, "X-linked amelia" is proposed.

Prenatal detection of Roberts-SC phocomelia syndrome: report of 2 sibs with characteristic manifestations

We describe 2 sibs with Roberts-SC phocomelia syndrome. Although an ultrasound scan performed at 13 weeks of gestation failed to identify specific abnormalities, repeat scan at 17 weeks detected tetraphocomelia. Ultrasonography can reliably detect Roberts-SC phocomelia prenatally; however, serial scans may be needed. Postmortem examination of the proposita confirmed the sonographic findings and also disclosed dysplastic kidneys and ovarian dysgenesis. The degree of phenotypic variation observed between the sibs supports the hypothesis that Roberts syndrome and SC phocomelia represent a single genetic entity.

C-anaphases in lymphocyte cultures versus premature centromere division syndromes

Different cases in which chromosomes obtained from short-term lymphocyte cultures appear with separated centromeres are reviewed. These include: (1) C-anaphases in the colchicine-resistance mutation, (2) C-anaphases as a common variant, (3) premature centromere division (PCD) in elderly women, (4) PCD in Alzheimer's disease, (5) early splitting and puffing of centromeres in Roberts' syndrome.

Roberts syndrome and SC phocomelia. A single genetic entity

A family with three siblings showing different manifestations of Roberts syndrome or SC phocomelia is described. With regard to previously published cases of familial Roberts syndrome and SC phocomelia we conclude that these two syndromes are one and the same genetic entity.

SC phocomelia syndrome, premature centromere separation, and congenital cranial nerve paralysis in two sisters, one with malignant melanoma

Two middle age sisters had most manifestations of the SC phocomelia syndrome including postnatal growth retardation, symmetric limb deficiencies with radial aplasia and absent thumbs, facial anomalies with microcephaly, microphthalmia, hypoplastic nasal alae, and borderline to mild mental retardation. Unusual findings included congenital paralysis of some cranial nerves in both patients and malignant melanoma in the proposita. Cultured lymphocytes from both patients, and skin fibroblasts, Epstein Barr virus-transformed lymphocytes, and tumor cells from the proposita demonstrated premature separation of centromeric heterochromatin (PCS) of many chromosomes, a finding noted previously in the SC phocomelia syndrome and the similar but more severe Roberts syndrome. Extensive overlap of the phenotypes of the sisters and 15 other patients with either syndrome and PCS confirms that these are either allelic conditions or the same disease--designated Roberts-SC phocomelia syndrome. The role of PCS in the syndrome(s) remains uncertain since some patients with the characteristic clinical phenotypes are reported to lack it.

Tetra-amelia with multiple malformations in six male fetuses of one kindred

An Arab Moslem kindred is reported in which six abnormal male fetuses were born in three closely related sibships. They had amelia, malformed head and other severe skeletal and visceral malformations. The similarities and differences between the developmental and inherent characteristics found in our patients and in families with Roberts syndrome are discussed.

Tetraphocomelia in the syndrome of thrombocytopenia with absent radii (TAR syndrome)

We report on an infant with the syndrome of Thrombocytopenia with Absent Radii (TAR) with severe lower-limb involvement. Amegakaryocytic thrombocytopenia was detected at 6 days when the platelet count was 11,000/microL. The platelet count increased steadily to 100,000/microL at 3 years. The patient required bilateral above-knee amputations for femorotibial synostoses. We recommend postponement of all elective operations until platelet counts are normal.

Premature separation of centromeres in marrow chromosomes from an untreated patient with acute myelogenous leukemia

Cytogenetic studies in an untreated patient with acute myelogenous leukemia revealed that greater than 60% of his marrow metaphases had pronounced anomalies in the centromere region. In the least affected chromosomes, the centromere appeared as a nonstaining hole, whereas in the most affected chromosomes, it appeared that the centromere segment had prematurely migrated at right angles to the telomeric portions. The population of mitoses exhibiting premature separation of the centromeres was reduced to virtually none during periods of drug induced remission. Our findings suggest that cytogenetic changes in malignant myeloid cells may be characterized by defects in centromere separation, as well as by alternations in karyotype.

Sequence of centromere separation: occurrence, possible significance, and control

This review describes the existence of a phenomenon, sequential separation of centromeres, in mitotic cells of various species including both animals and plants. Critical observations at metaanaphase show that the centromeres of chromosomes in a given genome do not separate into two sister units randomly, but that there is a genetically controlled, nonrandom, species-specific sequence which is independent of the length of the chromosome or the position of the centromere. A stricter control appears to exist for late-separating than for early-separating chromosomes. At early stages of metaanaphase several chromosomes initiate onset of separation simultaneously or in rapid succession, but late-separating chromosomes are better defined in their sequential position. The effect of Colcemid on the sequence of separation is minimal. It is proposed that aneuploidy in humans and other organisms may result from out-of-phase separation of a given chromosome. With the exception of chromosome No. 16, it appears that very early- or very late-separating centromeres are involved in human trisomies more often than those in between. Perhaps one function of centromeric heterochromatin is the control of centromere separation. The amount of such chromatin shows a positive correlation with the timing of separation of the centromeres. Superimposed upon this quantitative influence is the qualitative aspect, as discussed for various genomes. This suggestion explains a lack of extremely large quantities of heterochromatin near the centromere. Its existence in the form of homogeneously staining regions distal to the centromere, as in some cancer cells or in sex chromosomes, seemingly has no influence on the separation of centromeres. A brief discussion of centromere separation errors in human disease is provided, and suggestions for further studies are made.