Impact of the lung allocation score on survival beyond 1 year

Implementation of the lung allocation score (LAS) in 2005 led to transplantation of older and sicker patients without altering 1-year survival. However, long-term survival has not been assessed and emphasizing the 1-year survival metric may actually sustain 1-year survival while not reflecting worsening longer-term survival. Therefore, we assessed overall and conditional 1-year survival; and the effect of crossing the 1-year threshold on hazard of death in three temporal cohorts: historical (1995-2000), pre-LAS (2001-2005) and post-LAS (2005-2010). One-year survival post-LAS remained similar to pre-LAS (83.1% vs. 82.1%) and better than historical controls (75%). Overall survival in the pre- and post-LAS cohorts was also similar. However, long-term survival among patients surviving beyond 1 year was worse than pre-LAS and similar to historical controls. Also, the hazard of death increased significantly in months 13 (1.44, 95% CI 1.10-1.87) and 14 (1.43, 95% CI 1.09-1.87) post-LAS but not in the other cohorts. While implementation of the LAS has not reduced overall survival, decreased survival among patients surviving beyond 1 year in the post-LAS cohort and the increased mortality occurring immediately after 1 year suggest a potential negative long-term effect of the LAS and an unintended consequence of increased emphasis on the 1-year survival metric.

Fusion of two novel genes, RBM15 and MKL1, in the t(1;22)(p13;q13) of acute megakaryoblastic leukemia

t(1;22) is the principal translocation of acute megakaryoblastic leukemias. Here we show this chromosomal rearrangement to result in the fusion of two novel genes, RNA-binding motif protein-15 (RBM15), an RNA recognition motif-encoding gene with homology to Drosophila spen, and Megakaryoblastic Leukemia-1 (MKL1), a gene encoding an SAP (SAF-A/B, Acinus and PIAS) DNA-binding domain.

Structure and chromosome localization of the human CASP8 gene

The human CASP8 gene, whose product is also known as caspase 8 and FLICE, encodes an interleukin-1beta converting enzyme (ICE)-related cysteine protease that is activated by the engagement of several different death receptors. Caspase 8 is immediately recruited to the Fas receptor once it oligomerizes, and its protease activity is crucial for the apoptotic response generated by the resulting death-inducing signaling complex (DISC). We report here that the CASP8 gene contains at least 11 exons spanning approximately 30kb on human chromosome band 2q33-34. This region of human chromosome 2 was previously reported as the location of the CASP10 gene, whose product is closely related to caspase 8. Chromosome 2 band q33-34 is also involved in tumorigenesis, with loss of heterogeneity (LOH) being reported in a number of tumors. We also report EcoRI and HindIII polymorphisms that may prove to be useful in disease analysis. Both caspases 8 and 10 contain long pro-domains with duplicated death effector domains (DEDs), as well as their corresponding cysteine protease catalytic domains. Thus, it appears that CASP8 and CASP10 have evolved by tandem gene duplication, much like the CASP1, CASP4 and CASP5 gene cluster on human chromosome 11q22.2-22.3.

Efficacy of computerized decision support for mechanical ventilation: results of a prospective multi-center randomized trial

200 adult respiratory distress syndrome patients were included in a prospective multicenter randomized trial to determine the efficacy of computerized decision support. The study was done in 10 medical centers across the United States. There was no significant difference in survival between the two treatment groups (mean 2 = 0.49 p = 0.49) or in ICU length of stay between the two treatment groups when controlling for survival (F(1df) = 0.88, p = 0.37.) There was a significant reduction in morbidity as measured by multi-organ dysfunction score in the protocol group (F(1df) = 4.1, p = 0.04) as well as significantly lower incidence and severity of overdistension lung injury (F(1df) = 45.2, p < 0.001). We rejected the null hypothesis. Efficacy was best for the protocol group. Protocols were used for 32,055 hours (15 staff person years, 3.7 patient years or 1335 patient days). Protocols were active 96% of the time. 38,546 instructions were generated. 94% were followed. This study indicates that care using a computerized decision support system for ventilator management can be effectively transferred to many different clinical settings and significantly improve patient morbidity.

Myb-related Schizosaccharomyces pombe cdc5p is structurally and functionally conserved in eukaryotes

Schizosaccharomyces pombe cdc5p is a Myb-related protein that is essential for G2/M progression. To explore the structural and functional conservation of Cdc5 throughout evolution, we isolated Cdc5-related genes and cDNAs from Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and Homo sapiens. Supporting the notion that these Cdc5 gene family members are functionally homologous to S. pombe cdc5(+), human and fly Cdc5 cDNAs are capable of complementing the temperature-sensitive lethality of the S. pombe cdc5-120 mutant. Furthermore, S. cerevisiae CEF1 (S. cerevisiae homolog of cdc5(+)), like S. pombe cdc5(+), is essential during G2/M. The location of the cdc5-120 mutation, as well as mutational analyses of Cef1p, indicate that the Myb repeats of cdc5p and Cef1p are important for their function in vivo. However, we found that unlike in c-Myb, single residue substitutions of glycines for hydrophobic residues within the Myb repeats of Cef1p, which are essential for maintaining structure of the Myb domain, did not impair Cef1p function in vivo. Rather, multiple W-to-G substitutions were required to inactivate Cef1p, and many of the substitution mutants were found to confer temperature sensitivity. Although it is possible that Cef1p acts as a transcriptional activator, we have demonstrated that Cef1p is not involved in transcriptional activation of a class of G2/M-regulated genes typified by SWI5. Collectively, these results suggest that Cdc5 family members participate in a novel pathway to regulate G2/M progression.

Duplication of the DR3 gene on human chromosome 1p36 and its deletion in human neuroblastoma

The human DR3 gene, whose product is also known as Wsl-1/APO-3/TRAMP/LARD, encodes a tumor necrosis factor-related receptor that is expressed primarily on the surface of thymocytes and lymphocytes. DR3 is capable of inducing both NF-kappa B activation and apoptosis when overexpressed in mammalian cells, although its ligand has not yet been identified. We report here that the DR3 gene locus is tandemly duplicated on human chromosome band 1p36.2-p36.3 and that these genes are hemizygously deleted and/or translocated to another chromosome in neuroblastoma (NB) cell lines with amplified MYCN. Duplication of at least a portion of the DR3 gene, including the extracellular and transmembrane regions but not the cytoplasmic domain, was demonstrated by both fluorescence in situ hybridization and genomic Southern blotting. In most NB cell lines, both the DR3 and the DR3L sequences are simultaneously deleted and/or translocated to another chromosome. Finally, DR3/ Wsl-1 protein expression is quite variable among these NB cell lines, with very low or undetectable levels in 7 of 17 NB cell lines.

Bronchiolitis obliterans after lung transplantation: detection using expiratory HRCT

OBJECTIVE

The objective of this study was to determine if air trapping, as detected on expiratory high-resolution CT (HRCT), is useful as an indicator of bronchiolitis obliterans (BO) in lung transplant recipients.

MATERIALS AND METHODS

Corresponding inspiratory and expiratory HRCT images at five different levels and spirometry were obtained in 21 lung transplant recipients. Eleven patients had BO proved by transbronchial biopsy specimens; the remaining 10 patients had no pathologic or functional evidence of airways disease. Two "blinded" observers assessed the inspiratory images for the presence of bronchiectasis and mosaic pattern of lung attenuation, and the expiratory images for presence and extent of air trapping. Statistical comparison of the frequency of HRCT findings between patients with and without BO was performed using Fisher's Exact Test.

RESULTS

On inspiratory images, bronchiectasis and mosaic pattern of lung attenuation were present in 4 (36%) and 7 (64%) of 11 patients with BO, and 2 (20%) and 1 (10%) of 10 patients without BO (p>0.05 and p<0.05), respectively. The sensitivity, specificity, and accuracy of bronchiectasis and mosaic pattern for BO were 36%, 80%, and 57%, and 64%, 90%, and 70%, respectively. On expiratory images, air trapping was found in 10 of 11 (91%) patients with BO compared to 2 of 10 (20%) patients without BO (p<0.002). Air trapping was found to have a sensitivity of 91%, specificity of 80%, and accuracy of 86% for BO. Air trapping was identified in one patient with BO who had normal results of baseline spirometric function tests.

CONCLUSION

Air trapping, as detected on expiratory HRCT, was the most sensitive and accurate radiologic indicator of BO in the lung transplant population.

Characterization of human homologs of the Drosophila seven in absentia (sina) gene

Studies of Drosophila photoreceptor development have illustrated the means by which signal transduction events regulate cell fate decisions in a multicellular organization. Development of the R7 photoreceptor is best understood, and its formation is dependent on the seven in absentia (sina) gene. We have characterized two highly conserved human homologs of sina, termed SIAH1 and SIAH2. SIAH1 maps to chromosome 16q12 and encodes a 282-amino-acid protein with 76% amino acid identity to the Drosophila SINA protein. SIAH2 maps to chromosome 3q25 and encodes a 324-amino-acid protein that shares 68% identity with Drosophila SINA and 77% identity with human SIAH1. SIAH1 and SIAH2 were expressed in many normal and neoplastic tissues, and only subtle differences in their expression were noted. However, one of three murine homologs, Siah1B, was strongly induced in fibroblasts undergoing apoptotic cell death. While a previous study suggested that SINA was a nuclear protein, epitope-tagged SINA and SIAH1 proteins were found in the cytoplasm of Drosophila and mammalian cells. Their substantial evolutionary conservation, role in specifying cell fate, and activation in apoptotic cells suggest the SIAH proteins have important roles in vertebrate development. Furthermore, given the role of sina in Drosophila photoreceptor development, SIAH2 is a candidate for the Usher syndrome type 3 gene at chromosome 3q21-q25.

Cloning and chromosomal location of a novel member of the myotonic dystrophy family of protein kinases

We have cloned a novel serine/threonine protein kinase (PK428) which is highly related (65%) within the kinase domain to the myotonic dystrophy protein kinase (DM-PK), as well as the cyclic AMP-dependent protein kinase (33%). Northern blots demonstrate that PK428 mRNA is distributed widely among tissues and is expressed at the highest levels in pancreas, heart, and skeletal muscle, with lower levels in liver and lung. Two PK428 mRNAs 10 and 3.8 kilobase pairs in size are seen in a number of cell lines, including hematopoietic and breast cancer cells. An antibody generated to a glutathione S-transferase-PK428 fusion protein detects a 65-kDa protein in these cell lines, and a similarly sized protein when the cloned cDNA is transiently expressed in Cos 7 cells. Immunoprecipitation of the transiently expressed PK428 protein and incubation with [gamma-32P]ATP demonstrate that it is capable of autophosphorylation. In addition, immunoprecipitates of the PK428 protein kinase also phosphorylated histone H1 and a peptide encoding a cyclic AMP-dependent protein kinase substrate. The gene corresponding to the 3.8-kb PK428 mRNA, and its corresponding 65-kDa protein, was isolated by polymerase chain reaction screening of a P1 phage human genomic library. Using this P1 phage clone as a probe, the PK428 gene was located on 1q41-42, a possible location for a human senescence gene, a gene associated with Rippling muscle disease, as well as a region associated with genetically acquired mental retardation.

Detection of the t(2;5)(p23;q35) and NPM-ALK fusion in non-Hodgkin's lymphoma by two-color fluorescence in situ hybridization

The non-Hodgkin's lymphoma (NHL) subset commonly referred to as large cell lymphoma (LCL) has historically been characterized by it's marked cytological, immunological, and clinical heterogeneity. One potential defining feature of these lymphomas, the t(2;5)(p23;q35), occurs in 25% to 30% of anaplastic LCLs and is also found in cases with diffuse large cell or immunoblastic morphology. We recently identified nucleophosmin (NPM) and anaplastic lymphoma kinase (ALK) as the genes on chromosomes 5 and 2, respectively, that are juxtaposed by this translocation. To provide a complementary approach to the use of classical cytogenetics or polymerase chain reaction-based methods for the detection of this abnormality, we have developed a two-color fluorescent in situ hybridization (FISH) assay for the t(2;5) that may be used for the analysis of both interphase nuclei and metaphase chromosomes. Three overlapping chromosome 5 cosmid clones located immediately centromeric to the NPM gene locus and an ALK P1 clone located telomeric to the chromosome 2 breakpoint were labeled with digoxigenin or biotin, respectively, and used to visualize the derivative chromosome 5 produced by the t(2;5), evident as juxtaposed or overlapping red and green fluorescent signals. This NPM-ALK FISH assay was initially validated by analysis of a series of cytogenetically characterized cell lines, with the presence of the der(5) chromosome showed specifically only in those lines known to contain the t(2;5). The assay was then applied in a blinded fashion to a series of eight cytogenetically t(2;5)-positive clinical specimens and seven known t(2;5)-negative cases, including three NHL and four Hodgkin's disease biopsy samples. Whereas the t(2;5)-negative cases were negative by FISH, all eight t(2;5)-positive cases were positive. One additional case, initially thought to be positive for the translocation by cytogenetics, was proven to not be a classic t(2;5) by interphase and metaphase FISH. These data indicate that the FISH assay described is a highly specific and rapid test that should prove to be a useful adjunct to the currently available methods for detection of the t(2;5).

The gene encoding LERK-7 (EPLG7, Epl7), a ligand for the Eph-related receptor tyrosine kinases, maps to human chromosome 5 at band q21 and to mouse chromosome 17

The eph-related receptors are the largest subfamily of receptor tyrosine kinases. Recently, we and others have identified seven different, but related, cDNAs encoding membrane-bound ligands for this family of receptors. One member, LERK-7, is attached to the cell membrane via glycosyl-phosphatidylinositol linkage and has been found to be a ligand for the eph-family receptors hek, elk, eck, and rek. Using PCR-based screening of human x rodent somatic cell hybrid DNAs, we have assigned the gene that encodes LERK-7 (EPLG7) to human chromosome 5. Fluorescence in situ hybridization to metaphase chromosome preparations using a genomic clone from the locus refined this localization to chromosome 5, band q21. In addition, Southern blot analysis of DNAs from interspecific backcross mice indicated that the mouse homologue Epl7 maps to a homologous region on chromosome 17.

cDNA cloning, tissue distribution, and chromosomal localization of myelodysplasia/myeloid leukemia factor 2 (MLF2)

A fusion gene between nucleophosmin (NPM) and myelodysplasia/myeloid leukemia factor 1 (MLF1) is formed by a recurrent t(3;5)(q25.1;q34) in myelodysplastic syndrome and acute myeloid leukemia. Here we report the identification of a novel gene, MLF2, which contains an open reading frame of 744 bp encoding a 248-amino-acid protein highly related to the previously identified MLF1 protein (63% similarity, 40% identity). In contrast to the tissue-restricted expression pattern of MLF1, the MLF2 messenger RNA is expressed ubiquitously. The MLF2 gene locus was mapped by fluorescence in situ hybridization to human chromosome 12p13, a chromosomal region frequently involved in translocations and deletions in acute leukemias of lymphoid or myeloid lineage. In a physical map of chromosome 12, MLF2 was found to reside on the yeast artificial chromosome clone 765b9. Southern blotting analysis of malignant cell DNAs prepared from a series of acute lymphoblastic leukemia cases with translocations involving chromosome arm 12p, as well as a group of acute myeloid leukemias with various cytogenetic abnormalities, failed to reveal MLF2 gene rearrangements.

Der(16)t(1;16)(q21;q13) in Wilms' tumor: friend or foe

The der(16)t(1;16)(q21;q13) chromosomal abnormality has been reported rarely in Wilms' tumor. This abnormality has also been found in several other pediatric and adult neoplasms, and may imply a poor prognosis in at least some of these solid tumors. To investigate its clinical significance in Wilms' tumor, we examined the records of 65 consecutive children with Wilms' tumor whose tumor cells were successfully karyotyped. The t(1;16) was present in seven patients (10%) whose ages ranged from 2.5 to 4.7 years (median 3.5 years) at diagnosis. Six of the seven patients were female. All four stages of Wilms' tumor were represented (two patients had stage IV disease). No patient had bilateral disease. All tumors were of "favorable histology." All seven patients are alive and off therapy with a median follow-up of 3.2 years (range, 2 to 8.5 years). One patient with this abnormality developed brain metastases within 4 months of completion of therapy. Comparison of these patients with the remaining 58 Wilms' tumor patients revealed no significant differences with regard to disease stage, histology, survival, or relapse-free survival. Cytogenetic evidence of der(16)t(1;16)(q21;q13) in Wilms' tumor does not appear to portend an adverse clinical outcome, although only a larger study that includes molecular detection methods can provide more conclusive evidence.

T cell receptor biases and clonal proliferations among lung transplant recipients with obliterative bronchiolitis

Obliterative bronchiolitis (OB) is the most serious late complication of lung transplantation, but the pathogenesis of this disorder has not been elucidated. We sought evidence that OB is mediated by a cellular immunologic response by characterizing T cell antigen receptor beta-chain variable gene (TCRBV) repertoires in lung allograft recipients. Expression levels of 27 TCRBV among recipients were determined by multiprobe RNase protection assay after PCR amplification. In comparison to recipients with no evidence of rejection (n = 9), the PBL TCRBV repertoires of OB subjects (n = 16) exhibited more frequent expansions (16 vs. 9% of all measured TCRBV, P < 0.02), and the magnitudes of these abnormalities were greater (8.2 +/- 0.8 vs. 4.5 +/- 0.3 SD from mean normal values, P < 0.01). TCRBV sequencing showed these expansions were composed of clonal or oligoclonal populations. Thus, T cell responses in the recipients are marked by highly selective clonal expansions, presumably driven by indirect recognition of a limited number of immunodominant alloantigens. These processes are exaggerated among allograft recipients with OB, implying that cognate immune mechanisms are important in the pathogenesis of the disorder. Furthermore, the prominence of finite, distinct TCR phenotypes raise possibilities for development of novel diagnostic modalities and targeted immunotherapies for OB and other manifestations of chronic allograft rejection.

The genes encoding the eph-related receptor tyrosine kinase ligands LERK-1 (EPLG1, Epl1), LERK-3 (EPLG3, Epl3), and LERK-4 (EPLG4, Epl4) are clustered on human chromosome 1 and mouse chromosome 3

Hek and elk are members of the eph-related family of receptor tyrosine kinases. Recently, we isolated five cDNAs encoding membrane-bound ligands to hek and elk. Because of the promiscuous nature of their binding, we have termed these proteins ligands of the eph-related kinases or LERKs. The LERKs can be divided into two subgroups by virtue of their sequence identity, binding properties, and mode of cell membrane attachment. For example, LERK-2 (EPLG2, Epl2) and LERK-5 (EPLG5, Epl5) are type 1 transmembrane proteins, while LERK-1 (EPLG1, Epl1), LERK-3 (EPLG3, Epl3), and LERK-4 (EPLG4, Epl4) are anchored to the membrane by glycosyl-phosphatidylinositol (GPI) linkage. Using Southern hybridization analysis of human x rodent somatic cell hybrid DNAs, we have assigned the genes that encode the GPI-anchored LERKs (EPLG1, EPLG3, and EPLG4) to human chromosome 1. Fluorescence in situ hybridization to metaphase chromosome preparations using genomic clones from each locus refined this localization to chromosome 1, bands q21-q22. In addition, Southern blot analysis of DNA from interspecific backcross mice indicated that the mouse homologues Epl1, Epl3, and Epl4 map to a homologous region on mouse chromosome 3.

The gene for calcium-modulating cyclophilin ligand (CAMLG) is located on human chromosome 5q23 and a syntenic region of mouse chromosome 13

The CAMLG gene encodes a novel cyclophilin B-binding protein called calcium-modulating cyclophilin ligand, which appears to be involved in the regulation of calcium signaling in T lymphocytes and other cells. The murine homolog, Caml, was localized by interspecific backcross analysis to the middle of chromosome 13. By fluorescence in situ hybridization, this gene was localized to human chromosome 5 in a region (q23) known to be syntenic to mouse chromosome 13. These results provide further evidence supporting the extensive homology between human chromosome 5q and mouse chromosome 13. In addition, the results will provide a basis for further evaluation of cytogenetic anomalies that may contribute to inherited defects in calcium signaling or immune system function.

Obliterative bronchiolitis after lung and heart-lung transplantation

Obliterative bronchiolitis (OB) has emerged as the main cause of morbidity and mortality in the long-term follow-up after lung and heart-lung transplantation. The pathogenesis of OB is multifactorial, with acute rejection and cytomegalovirus infection being the main risk factors for the development of OB. The final common pathway of all inciting events seems to be an alloimmune injury, with subsequent release of immunologic mediators and production of growth factors leading to luminal obliteration and fibrous scarring of the small airways. Analyzing the 14 years of experience in 163 patients at Stanford University, we found a current incidence of bronchiolitis obliterans syndrome or histologically proven OB within the first 3 years after lung and heart-lung transplantation of 36.3%, with an overall prevalence of 58.1% after heart-lung and 51.4% after lung transplantation. Both pulmonary function indices (forced expiratory flow between 25% and 75% of forced vital capacity and forced expiratory volume in 1 second) and transbronchial biopsies have proven helpful in diagnosing bronchiolitis obliterans syndrome or OB at an early stage. Early diagnosis of OB and improved management have achieved survival rates in patients with OB after 1, 3, 5, and 10 years of 83%, 66%, 46%, and 22%, compared with 86%, 83%, 67%, and 67% in patients without OB. Recently, different experimental models have been developed to investigate the cellular and molecular events leading to OB and to evaluate new treatment strategies for this complication, which currently limits the long-term success of heart-lung and lung transplantation.

Detection of the t(2;13)(q35;q14) and PAX3-FKHR fusion in alveolar rhabdomyosarcoma by fluorescence in situ hybridization

Cytogenetic studies of the pediatric solid tumor alveolar rhabdomyosarcoma have demonstrated the presence of a consistent chromosomal translocation, t(2;13)(q35;q14). We recently identified PAX3 and FKHR as the genes on chromosomes 2 and 13, respectively, that are juxtaposed by this translocation. As one means of detecting the t(2;13) translocation in clinical specimens, we have developed a fluorescence in situ hybridization (FISH) assay that may be used for both interphase and metaphase cells. Translocation of the 5' region of the FKHR gene to the derivative chromosome 2, and retention of the 3' region of FKHR on the derivative chromosome 13 [(der(13)], were demonstrated in metaphase cells from a rhabdomyosarcoma cell line with a previously identified t(2;13) translocation. A 5' PAX3 cosmid probe was shown to localize to 2q35 in normal cells, and to translocate to the der(13) in the rhabdomyosarcoma cell line. In order to detect the der(13) in interphase nuclei, we labeled the 3'FKHR and the 5'PAX3 cosmid probes with digoxigenin and biotin, respectively, and used these in a two-color FISH assay. The presence of the der(13) was visualized as juxtaposed or overlapping red and green signals in metaphase and interphase tumor cells. The PAX3-FKHR FISH assay was then applied to a series of cytogenetically characterized pediatric sarcoma cell lines. The presence of the der(13) was demonstrated by FISH in all cases containing a cytogenetically detectable t(2;13). The FISH assay was then applied to a series of 20 embryonal and alveolar rhabdomyosarcoma samples. All 10 of the alveolar rhabdomyosarcoma specimens demonstrated a der(13) with the FISH assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromosomal assignment and genomic structure of Il15

Interleukin-15 (IL-15) is a novel cytokine whose effects on T-cell activation and proliferation are similar to those of interleukin-2 (IL-2), presumably because IL-15 utilizes the beta and gamma chains of the IL-2 receptor. Murine IL-15 cDNA and genomic clones were isolated and characterized. The murine Il15 gene was found to consist of eight exons spanning at least 34 kb and was localized to the central region of mouse chromosome 8 by interspecific backcross analysis. Intron positions in a partial human IL15 genomic clone were identical with positions of corresponding introns in the murine gene. The human IL15 gene was mapped to human chromosome 4q31 by fluorescence in situ hybridization.

Assignment of the human MAD and MXI1 genes to chromosomes 2p12-p13 and 10q24-q25

MAD and MXI1, two recently described members of the basic helix-loop-helix (bHLH) gene family, encode proteins that dimerize with and modulate the DNA binding of max. In turn, mad-max or mxi1-max heterodimers or max homodimers can compete for DNA binding sites with dimers formed between max and myc oncoproteins and antagonize the transcriptional activities of this latter class of proteins. Using a combination of somatic cell mapping and fluorescence in situ hybridization techniques, we have determined the chromosomal locations of the MAD and MXI1 genes. The MAD gene maps to chromosome 2p12-p13, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias as well as non-lymphocytic leukemias and Hodgkin disease. The MXI1 gene localizes to chromosome 10q24-q25, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias and prostatic carcinomas. The availability of genomic clones of MAD and MXI1 will permit an assessment of their involvement in these diseases at the molecular level.