Non-Secretory Multiple Myeloma Associated With High-Risk Phenotype and Complex Cytogenetics Including t(8;22).

Multiple myeloma (MM) is a plasma cell dyscrasia which is typically characterized by identifiable paraprotein in the blood or urine. However, the minority of patients in whom paraprotein cannot be identified are designated non-secretory MM (NSM). Evaluation of treatment response is more difficult in these patients as paraprotein levels cannot be followed. A dearth of clinical trials including these patients exists because of an inability to measure response by classical serum and urine measurement mechanisms as well as seemingly decreased overall survival compared to secretory MM. NSM is subdivided into four subgroups: "non-producers", "true non-secretors", "oligosecretors" and "false non-secretors". The "non-producers" phenotype is associated with more aggressive disease course. Translocations such as those involving the proto-oncogene c-MYC (chromosome 8) and the lambda light chain gene IGL (chromosome 22) - more commonly associated with Burkitt lymphoma - are rare in MM. We describe a 60-year-old male with NSM who was identified as having multiple high-risk features including complex cytogenetics and a non-producer phenotype, which are features not considered in conventional MM staging and risk stratification. This case highlights the need for awareness of phenotypes and cytogenetics associated with higher clinical risk that are not included in the revised International Staging System.

Male-to-female sex ratios of abnormalities detected by fluorescence in situ hybridization in a population of chronic lymphocytic leukemia patients.

Distorted sex ratios occur in hematologic disorders. For example, chronic lymphocytic leukemia (CLL) displays disproportionate sex ratios with a large male excess. However, the underlying genetics for these disparities are poorly understood, and gender differences for specific cytogenetic abnormalities have not been carefully investigated. We sought to provide an initial characterization of gender representation in genetic abnormalities in CLL by using fluorescence in situ hybridization (FISH). We confirm the well known skewed male-tofemale (M/F sex ratio) of ~1.5 in our CLL study population, but also determine the genotypic M/F sex ratio values corresponding to specific FISH DNA probes. Genetic changes in CLL detectable by four FISH probes were statistically compared with respect to gender. Initial FISH evaluations of 4698 CLL patients were retrospectively examined and new findings of the genotypic M/F sex ratios for these probes are reported. This study represents the largest CLL survey conducted in the United States using FISH probes. The CLL database demonstrated that FISH abnormalities (trisomy 12, 13q14.3 deletion and 17p13.1 deletion) probes had skewed M/F ratios of ~1.5. Also, by statistical analysis it was shown that ATM gene loss (11q22.3q23.1 deletion) solely or with other abnormalities was considerably higher in males with an M/F ratio of 2.5 and significantly different from M/F ratios of 1.0 or 1.5. We hypothesize that interactions involving these autosomal abnormalities (trisomy 12, and deletions of 11q22.3, 13q14.3, and 17p13.1), and the sex chromosomes may provide the genetic basis for the altered phenotypic M/F ratio in CLL.

Identification of parental chromosomes involved in translocations BCR-ABL, t(9;22) and PML-RARA, t(15;17).

Cells of blood and bone marrow often exhibit a genome- or ploidywise organization of the two haploid sets, representing apparently maternal and paternal chromosomes in interphase nuclei and in metaphase spreads. This provides the opportunity to perform "genomic karyotyping." Such application of karyotyping may indicate whether two chromosomes involved in a translocation are both maternal, both paternal, or intermingled, i.e., one maternal and the other paternal (we refer to this as mixed). The parental origin for these translocations likely has profound differences and implications in disease expression and response to treatments, making such information very important to personalized medicine. In this mini-review, we present our observations from specimens with translocations BCR-ABL, t(9;22) and PML-RARA, t(15;17). About 20% metaphases of these specimens indicated ploidywise organization and were amenable to genomic karyotyping analysis. Fluorescence in situ hybridization (FISH) probes for BCR-ABL translocation suggest a close approximation of the HSA 9 and 22, as control values for false-positive signals run from approximately 5-10%. Given a ploidywise distribution of the maternal and paternal sets of chromosomes, it would be expected that the chromosomes involved in the translocation t(9;22) would more often belong to one of the two genomes, either maternal or paternal. Contrastingly, HSA 15 and 17 are not considered as spatially close to each other and therefore an intragenomic involvement would be rarer for translocation t(15;17). In 14 out of the 21 (66.6%) specimens with informative metaphases, the chromosomes involved in the translocation BCR-ABL were restricted to one of the two genomes--either maternal or paternal. In cases of translocation PML-RARA only 4 out of 21 (19.1%) specimens indicated an intragenomic involvement. These simple yet informative analyses of cancer-related translocations show profound underlying genomic origins and lend support to genomic karyotyping.

Biphasic chromatin structure and FISH signals in reflect intranuclear order.

BACKGROUND AND AIM: One of the two parental allelic genes may selectively be expressed, regulated by imprinting, X-inactivation or by other less known mechanisms. This study aims to reflect on such genetic mechanisms. MATERIALS AND METHODS: Slides from short term cultures or direct smears of blood, bone marrow and amniotic fluids were hybridized with FISH probes singly, combined or sequentially. Two to three hundred cells were examined from each preparation. RESULTS AND SIGNIFICANCE: A small number of cells (up to about 5%), more frequent in leukemia cases, showed the twin features: (1) nuclei with biphasic chromatin, one part decondensed and the other condensed; and (2) homologous FISH signals distributed equitably in those two regions. The biphasic chromatin structure with equitable distribution of the homologous FISH signals may correspond to the two sets of chromosomes, supporting observations on ploidywise intranuclear order. The decondensed chromatin may relate to enhanced transcriptions or advanced replications. CONCLUSIONS: Transcriptions of only one of the two parental genomes cause allelic exclusion. Genomes may switch with alternating monoallelic expression of biallelic genes as an efficient genetic mechanism. If genomes fail to switch, allelic exclusion may lead to malignancy. Similarly, a genome-wide monoallelic replication may tilt the balance of heterozygosity resulting in aneusomy, initiating early events in malignant transformation and in predicting cancer mortality.