Partial monosomy and partial trisomy 18 in two offspring of carrier of pericentric inversion of chromosome 18.
(1/1109)
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)
Der(22) syndrome and velo-cardio-facial syndrome/DiGeorge syndrome share a 1.5-Mb region of overlap on chromosome 22q11.
(2/1109)
Derivative 22 (der[22]) syndrome is a rare disorder associated with multiple congenital anomalies, including profound mental retardation, preauricular skin tags or pits, and conotruncal heart defects. It can occur in offspring of carriers of the constitutional t(11;22)(q23;q11) translocation, owing to a 3:1 meiotic malsegregation event resulting in partial trisomy of chromosomes 11 and 22. The trisomic region on chromosome 22 overlaps the region hemizygously deleted in another congenital anomaly disorder, velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS). Most patients with VCFS/DGS have a similar 3-Mb deletion, whereas some have a nested distal deletion endpoint resulting in a 1.5-Mb deletion, and a few rare patients have unique deletions. To define the interval on 22q11 containing the t(11;22) breakpoint, haplotype analysis and FISH mapping were performed for five patients with der(22) syndrome. Analysis of all the patients was consistent with 3:1 meiotic malsegregation in the t(11;22) carrier parent. FISH-mapping studies showed that the t(11;22) breakpoint occurred in the same interval as the 1.5-Mb distal deletion breakpoint for VCFS. The deletion breakpoint of one VCFS patient with an unbalanced t(18;22) translocation also occurred in the same region. Hamster-human somatic hybrid cell lines from a patient with der(22) syndrome and a patient with VCFS showed that the breakpoints occurred in an interval containing low-copy repeats, distal to RANBP1 and proximal to ZNF74. The presence of low-copy repetitive sequences may confer susceptibility to chromosome rearrangements. A 1.5-Mb region of overlap on 22q11 in both syndromes suggests the presence of dosage-dependent genes in this interval. (+info)
Trisomies 8 and 20 characterize a subgroup of benign fibrous lesions arising in both soft tissue and bone.
(3/1109)
Trisomy 8 and trisomy 20 are nonrandom aberrations in desmoid tumors. The presence of these trisomies in related benign fibrous lesions of bone has not been previously addressed. In this study, 22 specimens from 19 patients diagnosed with desmoid tumor, desmoplastic fibroma, periosteal desmoid tumor, osteofibrous dysplasia, or fibrous dysplasia were examined by cytogenetic analysis of short-term cultures and bi-color fluorescence in situ hybridization of cytological touch preparations or paraffin-embedded tissue with centromeric probes for chromosomes 8 and 20. Trisomy 8 and trisomy 20 were detected by molecular cytogenetic methodologies in 15 specimens, including 10 primary bone lesions. Traditional cytogenetic analysis revealed trisomy 8 in two cases of osteofibrous dysplasia. Our findings demonstrate that trisomy 8 and trisomy 20 are also nonrandom aberrations in histologically similar, but clinically distinct, benign fibrous lesions of bone. (+info)
Severe mental retardation in a boy with partial trisomy 10q and partial monosomy 2q.
(4/1109)
A severely mentally subnormal child with many physical stigmata was shown to have the karyotype 46,XY,-2,+der(2),t(2;10)(q31;q24)pat. Full evaluation of this patient's karyotype depended on the family studies. It was shown that a balanced translocation t(2,10) was present in 4 normal males in 3 generations. (+info)
Partial trisomy D: a diagnostic and cytogenetic dilemma.
(5/1109)
An 18-month-old proposita with psychomotor retardation and other congenital abnormalities is presented. Chromosomal analysis of both parents proved normal. However, the karyotype of the proposita contained 47 chromosomes in both lymphocytes and cultured fibroblasts. The marker chromosome proved to be a deleted No. 14 or 15. Comparison of the reported cases of partial trisomy D indicates that a definitive clinical syndrome is not apparent in either case. (+info)
Evaluation of trisomy 12 by fluorescence in situ hybridization in peripheral blood, bone marrow and lymph nodes of patients with B-cell chronic lymphocytic leukemia.
(6/1109)
BACKGROUND AND OBJECTIVE: Trisomy 12 is the most common numerical chromosomal aberration in patients with B-cell chronic lymphocytic leukemia (B-CLL). Fluorescence in situ hybridization (FISH) has improved the detection of this cytogenetic abnormality and has made detection possible in all phases of the cell cycle. The presence of the trisomy 12 positive (+12) cell population has generally been investigated in leukemic cells obtained from the peripheral blood of CLL patients. To ascertain whether trisomy 12 is expressed homogeneously in cells of different hemopoietic tissues, we applied FISH to lymph node, peripheral blood and bone marrow samples obtained simultaneously from 23 untreated B-CLL patients. DESIGN AND METHODS: Twenty-three newly diagnosed patients with B-CLL, 15 in stage B and 8 in stage C, were included in the present study. Peripheral blood smears, bone marrow aspirate smears and lymph node touch imprints were collected from each patient at diagnosis. Cytologic preparations were examined by light microscopy in order to assess the lymphocyte morphology. Immunophenotyping was performed by cytofluorimetric analysis of the peripheral blood, bone marrow and lymph node mononuclear cell suspensions. The diagnosis was supported in all cases by histologic findings in bone marrow biopsy and lymph node biopsy specimens. Fluorescence in situ hybridization was performed on smears of blood and aspirated bone-marrow and lymph node touch imprints obtained by fresh tissue apposition. RESULTS: In 6 of the 23 cases (26%) trisomy 12 was clearly present in all tissues examined. A comparative analysis of the three different hemopoietic tissues was performed. A higher percentage of leukemic CD5+CD23+ cells was detected in lymph nodes than in peripheral blood and bone marrow. A significantly higher proportion of trisomic cells was observed in lymph nodes samples than in peripheral blood or bone marrow smears of trisomy 12 positive CLL patients. INTERPRETATION AND CONCLUSIONS: Several previous reports show that only a proportion of malignant B-CLL cells carry trisomy 12 when analyzed by interphase FISH. The higher proportion of +12 cells in lymph nodes than in peripheral blood or bone marrow of CLL patients with trisomy 12 could reflect different cell distributions in different tissues, or lymph node specific tropism, or proliferative advantage in selected tissue. At present, the role of trisomy 12 in the pathogenesis of lymphoproliferative disorders is unclear. (+info)
Asynchronous replication of alleles in genomes carrying an extra autosome.
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Transcriptional activity of genes appears to be highly related to their replication timing; alleles showing the common biallelic mode of expression replicate highly synchronously, whereas those with a monoallelic mode of expression replicate asynchronously. Here we used FISH to determine the level of synchronisation in replication timing of alleles in amniotic fluid cells derived from normal foetuses and from those with either of the trisomies for autosomes 21, 18 or 13, or for sex chromosomes (47,XXX and 47,XXY). Two pairs of alleles, not associated with the extra chromosome, were studied in subjects with each trisomy and three in normal subjects. In cells derived from normal foetuses and from foetuses with sex chromosome trisomies, each pair of alleles replicated synchronously; yet these very same alleles replicated asynchronously in cells derived from foetuses with trisomy for any of the three autosomes studied. The results suggest that the gross phenotypic abnormalities associated with an extra autosome are brought about not only by over-expression of genes present in three doses, but also by modifications in the expression of genes present in the normal two doses. (+info)
Trisomy 10: first-trimester features on ultrasound, fetoscopy and postmortem of a case associated with increased nuchal translucency.
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We report a case of the prenatal diagnosis of trisomy 10 in a fetus presenting with an increased nuchal translucency thickness (5 mm) on a routine first-trimester anomaly scan at 12 weeks' gestation. Multiple abnormalities were diagnosed by ultrasound and fetoscopy. Karyotyping on chorionic villus sampling led to the diagnosis of homogeneous trisomy 10 which was confirmed by in situ hybridization on fetal tissue samples. Postmortem examination confirmed major anatomical malformations, including facial cleft, arthrogryposis of the upper and lower limbs and bilateral diaphragmatic hernia, and also revealed hypoplastic lungs, right renal agenesis and a complex cardiac malformation. Trisomy 10 is an uncommon chromosomal abnormality that is likely to be associated with increased fetal nuchal translucency. This case also emphasizes the value of a detailed anomaly scan in high-risk patients in the first trimester of pregnancy. (+info)