1/404. Phenotypic variability in the chromosome 9 ring. The syndrome associated to the 9 ring is not commonly observed. The first remark was by Kistenmacher (1970) who examined a male. Later observation of other cases has allowed the syndrome to be described, so that it can be said to be characterized by constant signs, such as microcephaly, psychomotor retardation of varying entity and facial dysmorphism corresponding to that observed in 9 p monosomy. The variability of the phenotype has to be compared with the entity of the telomeric deletion, since the clinical outlook, especially the entity of retardation, could be less serious in case of small deletions. ( info) |
2/404. Ring chromosome 14 complicated with complex partial seizures and hypoplastic corpus callosum. A Japanese male with mosaicism of ring chromosome 14 and chromosome 14 monosomy is described. He demonstrated the characteristic morphologic features of ring chromosome 14, in addition to mental retardation and epileptic seizures. Clusters of complex partial seizures, one of which originated in the left frontocentral region on electroencephalographic monitoring, were evident. His seizures responded to phenobarbital, and his mental and motor development was only mildly retarded. magnetic resonance imaging revealed a hypoplastic corpus callosum, previously unknown in association with this syndrome. ( info) |
3/404. insulin dependent diabetes mellitus (IDDM) and autoimmune thyroiditis in a boy with a ring chromosome 18: additional evidence of autoimmunity or IDDM gene(s) on chromosome 18. A 4 year 3 month old boy with insulin dependent diabetes mellitus (IDDM), autoimmune thyroiditis, slight mental retardation, facial dysmorphism, and a de novo ring chromosome 18 (deletion 18q22.3-18qter) is described. This unique association of defects could represent a chance association. Alternatively, the clinical features could be the result of the chromosomal aberration. If so, one could speculate that a gene or genes on chromosome 18 might act as a suppressor or activator of the autoimmune process by itself or in concert with other IDDM loci. ( info) |
4/404. A case of dermatofibrosarcoma protuberans with a ring chromosome 5 and a rearranged chromosome 22 containing amplified COL1A1 and PDGFB sequences. dermatofibrosarcoma protuberans (DFSP) is a cutaneous tumour of borderline malignancy, the cytogenetic features of which include the translocation t(17;22)(q22;q13) or, more commonly, supernumerary ring chromosomes containing material from 17q22 and 22q13. These rearrangements result in the COL1A1/PDGFB fusion gene. Here, we describe a case of DFSP displaying a ring chromosome 5 together with a large marker chromosome composed of chromosome 22 alphoid dna, material from distal 12q and amplified COL1A1 and PDGFB sequences. This is the first case of DFSP with multiple copies of COL1A1 and PDGFB not confined to ring chromosomes, showing that DFSP is similar to other borderline malignant mesenchymal tumours, where rings and giant markers are alternative vehicles for amplified material. ( info) |
| We report, for the first time, the cytogenetic and molecular genetic constitution of a human mesenchymoma. As in several other soft tissue sarcomas, supernumerary ring and rod-shaped marker chromosomes were observed next to an otherwise normal diploid karyotype. Comparative genomic in situ hybridization and whole chromosome painting experiments revealed that chromosome 1q21-q25 and 12q14-q15 sequences were amplified, and that these sequences resided on the supernumerary marker chromosomes. We assume that, in this malignant mesenchymoma, the observed chromosomal anomalies may be associated with its well differentiated liposarcomatous component. ( info) |
6/404. Ring 22 duplication/deletion mosaicism: clinical, cytogenetic, and molecular characterisation. A patient with several features consistent with duplication of 22q11.2 (cat eye syndrome or CES) was found to be mosaic for a dicentric double ring chromosome 22 on postnatal karyotyping of peripheral blood. The initial karyotype was 46,XX,r(22)(p12q13) [46]/46,XX,dic r(22)(p12q13; p12q13)[4]. The amount of material duplicated in the dic r(22) was determined to include and extend beyond the CES critical region into 22q13.3. However, karyotyping of lymphocytes and fibroblasts, at 27 and 13 months of age respectively, showed no dic r(22) present in any of the cells examined. We suggest that the CES features in this patient, and potentially in other ring cases with CES phenotypic features, might result from a high level of mosaicism for a dic r(22) during early fetal development. Usually this unstable dic r(22) is subsequently lost from most cells. ( info) |
7/404. Ring 2 chromosome: ten-year follow-up report. Cote et al. [1981: Ann Genet 24:231-235] suggested that ring chromosomes without a preceding deletion share a common pattern of phenotypic anomalies, independent of what chromosome is involved. The phenotype of such a "general ring syndrome" consists of growth failure without malformations, few or no minor anomalies, and mild-to-moderate mental retardation. We report on a patient with a ring 2 chromosome with features suggestive of silver-russell syndrome at birth and striking postnatal growth retardation with minor intellectual involvement supporting Cote's suggestion. This would be the ninth case of ring 2 chromosome published; the patient is the longest reported survivor, with a 10-year follow-up. ( info) |
8/404. 45,X/46,X,r(Y) karyotype transmitted by father to son after intracytoplasmic sperm injection for oligospermia. A case report. BACKGROUND: The advent of assisted reproductive techniques, such as intracytoplasmic sperm injection (ICSI), has permitted conception and successful pregnancy for an increasing population of infertile men. Approximately 13.7% of infertile men with aspermia and 4.6% with oligospermia have a coexistent chromosome abnormality. Although the ICSI procedure appears safe thus far, early studies are in progress to evaluate outcomes of such pregnancies. For men whose infertility is linked to genetic conditions, it is an unprecedented challenge to predict the potential effects on their offspring. CASE: At 18 weeks' gestation, a 45,X/46,X,r(Y) karyotype was found on genetic amniocentesis performed for advanced maternal age. The pregnancy was achieved by ICSI using sperm from the husband, who was infertile due to severe oligospermia. Subsequently the same karyotype was found in the father. To our knowledge, this is the first reported case of familial transmission of ring y chromosome. CONCLUSION: It is strongly recommended that ICSI and other new assisted reproductive techniques be preceded by genetic screening for male infertility as well as other indications warranted by the family history since traditional risk assessment may require revision and outcomes may be uncertain in some cases. ( info) |
9/404. Simultaneous occurrence of two supernumerary autosomal ring chromosomes r(1) and r(16) in twins. ring chromosomes are estimated to occur in 3/10000 newborns and the simultaneous occurrence of two autosomal rings must be a very rare event. Recently, the characterisation of these markers using fluorescence in situ hybridisation (FISH) has greatly enhanced cytogenetic-phenotypic correlations in patients with these marker chromosomes. This kind of analysis enabled us to clarify a unique karyotype containing a r(1) and a r(16) in identical twins born after a 26 week gestation with minimal somatic abnormalities. The origin of the rings was identified using a satellite and whole chromosome painting probes. FISH analysis showed the same abnormal female karyotype in both twins, 48,XX, r(1)(p13q21), r(16)(p11q11).ish r(1) (D1Z5 ,wcpl ), r(16)(D16Z2 ,wcp16 ) in about two thirds of the cells. Each also had minor clones with a normal female karyotype or with one or the other supernumerary ring. Half of the r(1) contained CBG band negative material and the r(16) appeared to be totally CBG band positive. These twins represent the second report of the simultaneous occurrence of multiple autosomal rings. Their description may help to delineate a new chromosome disorder and shows the usefulness of FISH analysis. ( info) |
10/404. Ring chromosome 9 with a 9p22.3-p24.3 duplication. A ring chromosome 9 containing an inverted 9p22.3-p24.3 duplication was found in a girl presenting with some of the phenotypic characteristics of ring 9 syndrome such as trigonocephaly, microcephaly, hypotelorism, micrognathia, single palmar crease, and bilateral clinodactyly. The typical facial dysmorphic features of 9p duplication, ascribed to trisomy of the band p22, were not present in this patient. Cytogenetic and molecular studies indicated that the duplicated region of band p22 in the ring is confined to the sub-band 22.3. CONCLUSION: The chromosome region responsible for the 9p duplication syndrome appears to be restricted to sub-bands p22. 1-22.2. ( info) |