Molecular cytogenetic evidence for a common breakpoint in the largest inverted duplications of chromosome 15.

Chromosomes from 20 patients were used to delineate the breakpoints of inverted duplications of chromosome 15 (inv dup[15]) that include the Prader-Willi syndrome/Angelman syndrome (PWS/AS) chromosomal region (15q11-q13). YAC and cosmid clones from 15q11-q14 were used for FISH analysis, to detect the presence or absence of material on each inv dup(15). We describe two types of inv dup(15): those that break between D15S12 and D15S24, near the distal boundary of the PWS/AS chromosomal region, and those that share a breakpoint immediately proximal to D15S1010.

Sex chromosome markers: characterization using fluorescence in situ hybridization and review of the literature.

Fluorescence in situ hybridization (FISH) using biotin labeled X- and Y-chromosome DNA probes was utilized in the analysis of 23 sex chromosome-derived markers. Specimens were obtained through prenatal diagnosis, because of a presumptive diagnosis of Ullrich-Turner syndrome, mental retardation, and minor anomalies or ambiguous genitalia; three were spontaneous abortuses. Twelve markers were derived from the X chromosome and eleven from the Y chromosome; this demonstrates successfully the value and necessity of FISH utilizing DNA probes in the identification of sex chromosome markers.

Construction and screening of a cosmid library generated from a somatic cell hybrid bearing human chromosome 15.

A cosmid library has been constructed with DNA isolated from a mouse/human hybrid cell line designated A15, which was previously characterized and shown to retain chromosome 15 as the only human material. The library was generated and stored as 34 independent pools of primary colonies at 8-10,000 colonies per pool. Screening colonies representing pools of this library by hybridization with a human-specific repetitive probe has facilitated the identification of random clones bearing human inserts.

Familial DiGeorge/velocardiofacial syndrome with deletions of chromosome area 22q11.2: report of five families with a review of the literature.

The DiGeorge (DG), velocardiofacial (VCF), and conotruncal anomaly-face (CTAF) syndromes were originally described as distinct disorders, although overlapping phenotypes have been recognized. It is now clear that all three syndromes result from apparently similar or identical 22q11.2 deletions, suggesting that they represent phenotypic variability of a single genetic syndrome.

Evidence for structural heterogeneity from molecular cytogenetic analysis of dicentric Robertsonian translocations.

Most Robertsonian translocations are dicentric, suggesting that the location of chromosomal breaks leading to their formation occur in the acrocentric short arm. Previous cytogenetic and molecular cytogenetic studies have shown that few Robertsonian translocations retain ribosomal genes or beta-satellite DNA. Breakpoints in satellite III DNA, specifically between two chromosome 14-specific subfamilies, pTRS-47 and pTRS-63, have been indicated for most of the dicentric 14q21q and 13q14q translocations that have been studied.

Application of FISH to complex chromosomal rearrangements associated with chronic myelogenous leukemia.

Identification of complex chromosomal rearrangements can be difficult, due either to the limited number and sometimes poor quality of metaphases in bone marrow preparations or to the nature of the rearrangements. Fluorescence in situ hybridization (FISH) using chromosome-specific DNA libraries in conjunction with a cosmid probe for the c-ABL oncogene was performed to substantiate the preliminary G-banded karyotypes of six patients with chronic myelogenous leukemia (CML). Our results indicate that FISH is sufficiently sensitive to detect complex and subtle rearrangements, even in bone marrow preparations with suboptimal metaphases, and can provide valuable corroborative information.

Molecular cytogenetic analysis of inv dup(15) chromosomes, using probes specific for the Prader-Willi/Angelman syndrome region: clinical implications.

Twenty-seven cases of inverted duplications of chromosome 15 (inv dup [15]) were investigated by FISH with two DNA probes specific for the Prader-Willi syndrome/Angelman syndrome (PWS/AS) region on proximal 15q. Sixteen of the marker chromosomes displayed two copies of each probe, while in the remaining 11 markers no hybridization was observed. A significant association was found between the presence of this region and an abnormal phenotype (P < .

Cytogenetic studies of primary cultures of esophageal squamous cell carcinoma.

Cytogenetic analysis was performed on primary cultures of 21 squamous cell carcinomas of the esophagus (SCCE). Seven cases exhibited mosaic clonal chromosome abnormalities distributed as follows: two contained tetraploid cell populations, one with t(3;7)(p21;q11); two showed loss of the Y chromosome, one with double minutes; single cases demonstrated der(11)t(4;11)(q?27;q23); add(1)(p35) and del(4)(p12); and del(7)(p13), del(7)(q22q34), and der(11)t(7;11)(p?15;p?13). The remaining 14 cases had apparently normal karyotypes, possibly derived from stromal elements.

Clarification of subtle reciprocal rearrangements using fluorescence in situ hybridization.

Fluorescence in situ hybridization (FISH) using chromosome-specific DNA libraries as painting probes was applied in the analysis of six subtle, balanced chromosome rearrangements. Both fresh and older slides, some of which had been previously G-banded, were used to determine if FISH could identify unambiguously very small amounts of translocated material. Our results indicate that this procedure can clearly and precisely distinguish the specific components of extremely subtle translocations, in different cell types, such as leukocytes, aminocytes, and chorionic villus, and irregardless of preparation age.

Fluorescent in situ hybridization (FISH): a new application in the delineation of true vs. pseudomosaicism in prenatal diagnosis.

Metaphase chromosomes and interphase nuclei from nine amniotic fluid cultures were studied with fluorescence in situ hybridization (FISH). The samples were initially analyzed with routine G-banding and were diagnosed as having true mosaicism (five patients) or pseudomosaicism (four patients). In our study, FISH analysis could provide additional information to distinguish pseudo- from true mosaicism by allowing interphase studies and analysis of an increased number of metaphase spreads.

Characterization of de novo duplications in eight patients by using fluorescence in situ hybridization with chromosome-specific DNA libraries.

Fluorescence in situ hybridization (FISH) with chromosome-specific DNA libraries was performed on samples from eight patients with de novo chromosomal duplications. In five cases, the clinical phenotype and/or cytogenetic evaluations suggested a likely origin of the duplicated material. In the remaining three cases, careful examination of the GTG-banding pattern indicated multiple possible origins; hybridization with more than one chromosome-specific library was performed on two of these cases.