| Bone-marrow cells from a patient with Bloom's syndrome cultured for 48 h in the presence of BudR exhibited a striking increase in the number of sister chromatid exchanges (SCEs) in comparison to that in the marrow cells of a patient with treated polycythemia vera (PV). Thus, it appears that an increased incidence of SCE in Bloom's syndrome occurs in various differentiated types of cells, not just blood lymphocytes, and constitutes the syndrome's most characteristic cytogenetic feature. In contrast, the incidence of SCE was not increased in marrow cells and lymphocytes of the particular PV patient studied here, whose cells did exhibit increased numbers of chromatid and chromosome gaps and breaks, presumably as result of the patient's earlier treatment. An increased frequency of SCE was demonstrated in Bloom's syndrome lymphocytes using both a technique based on BudR incorporation and one based on labeling with tritated deoxycytidine. This observation constitutes evidence against the increase of SCE being due to an unusual reaction to BudR. By conventional cytogenetic techniques, chromosome instability, including chromatid and chromosome breaks, but no homologous chromatid interchanges were also recognized in Bloom's syndrome bone-marrow cells incubated in vitro (without BudR) for either 1.k or 16 h. This observation points to the existence of chromosome instability in vivo. ( info) |
2/4845. Partial trisomy 20p derived from a t(18;20) translocation. Two sibs show a strikingly concordant syndrome of congenital anomalies and G-banding reveals that each has partial trisomy 20p resulting from a t(18;20) translocation. They resemble other cases of partial trisomy 20p in some respects but also differ in some ways. Their normal sib, mother, and half-aunt are balanced heterozygotes for the t(18;20) translocation. The segregation of the balanced translocation in this family is associated with an extremely poor reproductive record. The segregation pattern closely parallels that of a t(13;20) translocation in a family described by Carrel et al. (1971) and Francke (1972). The similarity of segregation patterns is predictable on the basis of probable pachytene configurations, but the dissimilarity of phenotypes between families is not readily explained. ( info) |
3/4845. trisomy 4p due to a paternal t(4p-;16p ) translocation. A patient is described carrying a duplication 4p12 leads to pter due to a paternal translocation: 46,XY,t(4;16) (p12;p13). Involvement of chromosome No. 16 and the heterogeneity of the clinical picture in cases with dup (4p) are discussed. ( info) |
4/4845. Partial monosomy 22 as the result of an unbalanced translocation 5:22 in a patient with cri-du-chat syndrome. A 2-year-old boy with features suggestive of cri-du-chat syndrome had a complex karyotype: 45,XY,--22,5p--,t(5p:22q). Clinical symptoms were catlike cry in early infancy, severe mental and motor retardation, failure to thrive, hypertelorism, antimongoloid slant of the eyes, ptosis of the eyelids, epicanthus, micrognathia, dermatoglyphics abnormalities, and partial syndactyly between 2nd and 3rd toes. ( info) |
5/4845. Chromosome 7 short arm deletion and craniosynostosis. A 7p-syndrome. A patient with craniosynostosis and a small deletion of part of the short arm of chromosome 7 is described. A review of the literature indicates that craniosynostosis has occurred in at least four of the five infants (the fifth having microcephaly) affected by structural changes (resulting in deletion) within the terminal region of the short arm of chromosome 7. ( info) |
6/4845. 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) |
7/4845. Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages. Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality. ( info) |
8/4845. Cri du chat syndrome and translocation t(5p--;18p ). Two new cases of "cri du chat" syndrome are reported in sisters aged 2 years and one month, respectively. These cases allowed us to detect a translocation t(5p--;18p ) in the mother and to study the familial segregation of this structural chromosome anomaly. At the same time, results from the dermatoglyphic analysis of the propositi as well as those of the carriers of the translocation are also reported. ( info) |
9/4845. Partial monosomy and partial trisomy 18 in two offspring of carrier of pericentric inversion of chromosome 18. A pericentric inversion of chromosome 18 is described in the mother of a patient with clinical diagnosis of 18q--syndrome. The propositus' chromosome complement includes the recombinant 18 with deficiency of the distal one-third of the long arm and duplication of the terminal segment of the short arm. The propositus' sister carrier the recombinant 18 with a duplication of the distal one-third of the long arm and a deficiency of the terminal segment of the short arm. The relative length of the inverted segment represents about 60% of the total chromosome 18 length. The probability of recombinant formation following the occurrence of a chiasma within the inverted segment is predicted to be high. ( info) |
10/4845. Sporadic bilateral retinoblastoma and 13q- chromosomal deletion. Unilateral retinoblastoma (Rb) is usually a sporadic occurrence while bilateral (multifocal) cases are often familial. Sporadic bilateral Rb associated with a long-arm deletion of a D-group chromosome has been reported in 8 children. We have studied a 6-year-old female with bilateral sporadic retinoblastoma, treated during infancy by enucleation and radiotherapy. chromosome banding studies on peripheral lymphocytes revealed an interstitial deletion from the long arm of a chromosome 13: del(13) (q12q14). Three additional patients reported in the literature had interstitial 13q- deletions, involving slightly different though overlapping regions. The only chromosomal region consistently missing in all of these 4 cases appears to be part of the lightly staining band 13q14. We, therefore, propose this site as the precise location of a gene (or genes) involved in retinal development. Our patient lacked features of the classic 13q- or 13-ring syndrome, which involves deletion of a more distal portion of the 13 long arm. When compared to reported patients with Rb and 13q-, it became apparent that there may be a separate recognizable syndrome consisting of moderate growth and developmental delay, characteristic facies and external ears, and bilateral sporadic Rb, which is associated with an interstitial 13q- deletion. ( info) |