Supernumerary ring chromosome: an etiology for Pallister-Killian syndrome?

Characterization of marker chromosomes before the introduction of array CGH (aCGH) assays was only based on their banding patterns (G, C, and NOR staining) and fluorescent in situ hybridization techniques. The use of aCGH greatly improves the identification of marker chromosomes in some cases. We describe an atypical case of Pallister-Killian syndrome (PKS) detected at prenatal diagnosis with a very unusual cytogenetic presentation: a supernumerary ring chromosome including two copies of 12p. A similar anomaly described in a postnatal patient suggests ring chromosome as a possible cause of PKS. Extra ring chromosomes might be a more common etiology for PKS than previously thought, given the difficulty in their characterization before the advent of aCGH.

Prenatal diagnosis of an interstitial 12q chromosome deletion

Rearrangements involving long arm of chromosome 12 are rare events. To our knowledge, we present the first case of an interstitial deletion of the long arm of chromosome 12 in a prenatal diagnosis. A review of the literature is included in our report.

Intranuclear arrangement of human chromosome 12 is reflected in metaphase chromosomes as non-random bending

We have found a high correlation of non-random bending of human metaphase chromosome 12 with the intranuclear arrangement deduced by Nogami et al. (Chromosoma 108 (2000) 514), providing further evidence of the relation of non-random bending and the interphase organization of the nucleus.

Prenatal detection of a paracentric inversion 16(q11.2q13)

We report the prenatal detection of an inherited paracentric inversion 16(q11.2q13).

Clinical application of multiplex quantitative fluorescent polymerase chain reaction (QF-PCR) for the rapid prenatal detection of common chromosome aneuploidies

The clinical application of quantitative fluorescent polymerase chain reaction (QF-PCR) for rapid prenatal detection of chromosome aneuploidies has been limited in most studies to the detection of autosomal trisomies. Recently it has been shown that a newly identified highly polymorphic marker, termed X22, which maps to the Xq/Yq pseudoautosomal region of the sex chromosomes, used together with the X-linked short tandem repeat (STR) HPRT, allows the accurate detection of gonosome aneuploidies. We have developed a rapid assay, which includes these STR markers together with a sequence of the amelogenin region of the sex chromosomes and selected highly polymorphic autosomal STR. Two more X chromosome markers, as yet not used in previous QF-PCR applications, were also included in the assay. The molecular test was then used in a clinical trial on 551 uncultured amniotic fluid samples, allowing the assessment of copy number for chromosomes X, Y and 21 in 100% of cases. In the course of this study, two fetuses with Turner's syndrome and one with Klinefelter's syndrome were identified along with 17 autosomal trisomies. The assay proved to be so efficient and reliable that in most aneuploidy cases, in which ultrasound findings were in agreement with the molecular result, therapeutical interventions were possible without waiting for the result of cytogenetic analysis.

Dicentric (17;18) in a case of atypical B-cell chronic lymphocytic leukemia

We report a new dic(17;18)(p11.2;p11.2) in a 61-year-old male patient diagnosed with atypical B-cell chronic lymphocytic leukemia. The dic(17;18)(p11.2;p11.2) was detected in 90%, 10%, and 100% of metaphases in the peripheral blood, bone marrow, and lymph node, respectively. Fluorescence in situ hybridization studies with chromosome 17 and 18 centromeric probes revealed the presence of two normal centromeres of both chromosomes 17 and 18. The centromere of one chromosome 17 was found together with the centromere of one chromosome 18, confirming the dicentric nature of the rearrangement. In addition, with the use of a 17p13.1 region probe, monosomy of the 17p13 region, where the Tp53 gene is located, was observed.

Cytogenetic and fluorescence in situ hybridization studies in four cases of plasma cell leukemia

We present a cytogenetic and fluorescence in situ hybridization (FISH) study, using centromeric probes for chromosomes 3, 7, 11, and 18, TP53 gene (17p13), and RB-1 locus (13q14) DNA probes, in four cases of plasma cell leukemia (PCL). Among the four cases, three presented monosomy of the RB-1 locus and one monoallelic deletion of the TP53 gene. The present report shows the usefulness of the FISH technique to detect abnormalities not previously observed by conventional cytogenetics.

Application of cross-species color banding (RxFISH) in the study of T-prolymphocytic leukemia

BACKGROUND AND OBJECTIVE

Cross-species color banding (RxFISH) is a new FISH technology based on the use of differentially labeled gibbon chromosome probes to obtain a specific color banding pattern for each human chromosome. The aim of the study was to test the RxFISH technique for better characterization of complex karyotypes in patients with T-prolymphocytic leukemia (T-PLL).

DESIGN AND METHODS

The study evaluated the cross-species color banding technique in four patients affected with T-PLL previously studied by conventional cytogenetics.

RESULTS

All patients showed an abnormal karyotype and three of them had a complex karyotype. The involvement of 14q11 in all four cases, the gain of 8q in three cases and a loss of chromosome 10, 15 and 17 and a gain of chromosome 21 in two cases were noted. The RxFISH technique identified from 2 to 7 not previously recognized aberrations per case and confirmed the inv(14)(q11q32).

INTERPRETATION AND CONCLUSIONS

To our knowledge, this is the first application of RxFISH to characterize chromosomal rearrangements in T-cell neoplasms. RxFISH gave rapid and easy identification of chromosome rearrangements that were difficult to recognize by conventional cytogenetics. Using this new technology we identified 15 rearrangements not detected by conventional cytogenetics.

Translocation (11;14)(q13;q32) and preferential involvement of chromosomes 1, 2, 9, 13, and 17 in mantle cell lymphoma

We have studied 13 cases of histologically confirmed mantle cell lymphomas (MCL) combining cytological-immunological features with conventional cytogenetics and in situ hybridization (ISH) techniques. Peripheral blood smears and lymph node biopsies expressed the typical mantle zone pattern with alpha B-cell phenotype. Most of the cases (11 of 13) had lymphomatous cells in the peripheral blood. Chromosome analysis was carried out on lymphoid cells from peripheral blood and/or lymph node biopsies. Phytohemagglutinin (PHA) and phorbol 12-myristate 13 acetate (TPA) were used as mitogens. Biotin-labeled libraries of whole chromosomes implicated in complex karyotypes were used to improve their interpretation. Clonal chromosome abnormalities were found in 10 of 13 patients (77%); 7 of these had a complex abnormality. The most frequent recurrent structural abnormalities were: t(11;14)(q13;q32), involvement of chromosome 1 (der[1], del[1], dup[1]), chromosome 2 (del[2], der[2]), chromosome 9 (der[9], -9), chromosome 13 (add[13], t[13q]), and chromosome 17 (add[17], der[17], t[17q]). The most frequent numerical abnormalities were monosomy 21 and loss of the Y chromosome.

Cytogenetic findings in five patients with hairy cell leukemia

We studied five cases of hairy cell leukemia (HCL) using conventional cytogenetics. All patients were diagnosed with typical HCL. Chromosome analysis was carried out on a 72-hour culture of peripheral blood. Phytohemagglutinin (PHA) mitogen was used. Clonal chromosome abnormalities were found in 2/5 patients (40%), a complex abnormality being identified in one of them. The chromosomes involved were: 1, 6, 7, 8, and 17. No patient showed trisomy 12 or a 14q+. An interesting result was the finding of del(7)(q32) as a sole anomaly.

[Interstitial 9q deletion: a primary change in acute non-lymphoblastic leukemia?]

Two cases of acute non-lymphoblastic leukaemia (ANLL), subtypes M1 and M5b, are presented. Both of them showed the 9q-interstitial deletion as the only abnormality. From our observations and others found in the literature it can be inferred that such abnormality might be a primary finding in ANLL, related to an unfavourable prognosis, regardless the morphological subtype.

Cytogenetic abnormalities in three patients with B-cell prolymphocytic leukemia

We present the cytological features, conventional cytogenetics, and in situ hybridization (ISH) findings of three cases of B-cell prolymphocytic leukemia (B-PLL). The diagnosis was made according to the French-American-British (FAB) criteria. We considered a diagnosis of B-PLL when a predominance (> 50%) of lymphoid cells with coarse chromatin but prominent central nucleoli and more abundant cytoplasm than typical chronic lymphocytic leukemia (CLL) cells were present. B-PLL express strong SIg, B-cell antigens, and reactivity with the monoclonal antibody FMC7. Chromosome analysis was carried out on lymphoid cells from peripheral blood and, in one patient, from lymph node. The phytohemagglutinin (PHA) mitogen was used. ISH was performed with two types of probes: the biotin-labeled chromosome 12-specific alpha satellite DNA probe to detect trisomy 12, and biotin-labeled libraries of whole chromosomes 1, 7, and 14. Clonal chromosome abnormalities were found in all three patients; in one, a complex karyotype was observed. The most frequent recurrent abnormality was trisomy 12. Our results suggest that PLL usually presents with cytogenetic abnormalities. The finding of translocation (11;14) is noteworthy; chromosomes 1 and 3 are also involved.