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Progression of follicular lymphoma to a higher-grade malignancy frequently heralds a poor prognosis. Clinical transformation is variably accompanied by a spectrum of histologic changes characterized by alteration in growth and cytology. Although several cytogenetic events and potential oncogenes have been documented in this progression, the underlying molecular mechanisms are largely unknown. We present five patients with an unusual histologic transformation of follicular lymphoma manifested by blastic/blastoid morphology. This transformation is histologically distinct from other types of transformation of follicular lymphoma. All five cases exhibited the t(14;18) translocation and expressed the BCL-2 protein. In addition, two of the five patients showed increased levels of the p53 protein within neoplastic cells implicating a possible role for this oncogene in blastic/blastoid transformation. The lack of BCL-1 and myeloid antigens by immunohistochemistry and flow cytometry studies served to distinguish blastic/blastoid transformation of follicular lymphoma from its morphologic mimics. This distinction is clinically important because lymphoblastic and myeloid leukemias require significantly different therapeutic modalities and show better prognosis. Moreover, the lack of Epstein-Barr virus-specific mRNA suggests that this virus is unlikely to participate in blastic/blastoid transformation of follicular lymphoma.

Most reported microdeletions of the CREB-binding protein (CBP) gene in the Rubinstein-Taybi syndrome (RTS) were detected by fluorescence in situ hybridization (FISH) with a single cosmid probe specific to the 3' region of the gene. In order to test the hypothesis that the rate of microdeletion-positive cases would be greater if the entire gene was evaluated, we performed FISH on 66 patients with an established diagnosis of RTS, using a panel of five cosmids that span the CBP gene. Five of 66 patients had deletions by FISH (9%), consistent with those rates reported in various series that ranged between 3-25%. Among our cases, different deletions were observed; one was deleted for the 5' but not the 3' region of the CBP gene (case 055). Other deletions included a total CBP deletion extending from the 5' through the 3' region (case 017), a deletion of all but the 5' region (cases 006 and 060), and an interstitial deletion in the 3' region (case 028). Fine breakpoint mapping with additional cosmid and yeast artificial chromosome (YAC) constructs was performed on these patients. The findings of a partial 5' deletion and of interstitial deletions of the CBP gene add to the known spectrum of mutations of this gene in RTS and demonstrate the need for evaluation of the entire CBP gene region for deletions rather than only the 3' region in RTS patients. These results further suggest that the true rate of microdeletion across the CBP gene detectable by FISH has yet to be established firmly. No phenotypic differences between partial deletion, complete deletion, and nondeletion patients were observed, supporting a haploinsufficiency model for RSTS.

Deletions of chromosome 6q are rare. We report 3 new patients with 6q deletions. Case 1 is a male with an interstitial deletion [del(6)(q13q14.2)], hypotonia, speech delays, and minor anomalies. Case 2 is a male with an interstitial deletion [del(6)(q16.2q22.32)] and malformations, including truncus arteriosus and bilateral oligodactyly. Case 3 is a male with a terminal deletion [del(6)(q25.2)] with retinal pits, hydrocephalus, atrioventricular canal, and hydronephrosis. The findings in our patients and those from 57 previously reported cases demonstrated 3 phenotypic groups associated with 6q deletions. Group A [del(6)(q11-q16)] had a high incidence of hernias, upslanting palpebral fissures, and thin lips with lower frequency of microcephaly, micrognathia, and heart malformations. Group B [del(6)(q15-q25)] was associated with increased intrauterine growth retardation, abnormal respiration, hypertelorism, and upper limb malformations. Group C [del(6)(q25-qter)] was associated with retinal abnormalities, cleft palate, and genital hypoplasia. The only universal finding among all patients with 6q deletions was mental retardation. Other findings common to all 3 groups included ear anomalies (90%), hypotonia (82%), and postnatal growth retardation (68%).

A patient with ring chromosome 6/monosomy 6 mosaicism is presented. At 25 weeks' gestation, ultrasound examination demonstrated fetal hydrocephalus. Amniocentesis was performed. The fetal karyotype was 45,XY,-6/ 45,XY,-6,+f/46,XY,r(6)(p25q27). Delivery of this male infant was by Caesarean section at 37 weeks' gestation. The karyotype in peripheral blood lymphocytes was 46,XY,r(6)(p25q27) with no indications of mosaicism. The infant had hydrocephalus which required treatment with a ventriculoperitoneal shunt at 22 days of age. He had no other obvious serious congenital anomalies. By 17 months he had developed microcephaly, seizures, severe bilateral hearing loss, and global development delay. This patient provides information regarding phenotypic variability of ring chromosome 6 and also reinforces the importance of offering amniocentesis if fetal hydrocephalus is detected as an isolated anomaly.

Cyclic nucleotides are important second messengers that mediate a number of cellular responses to external signals. Cyclic nucleotide phosphodiesterases play a role in signal transduction by regulating the cellular concentrations of these messengers. Here, we have applied Southern analyses of somatic cell hybrid lines and of recombinant inbred (RI) mouse strains as well as fluorescence chromosomal in situ hybridization (FISH) to chromosomally localize five cAMP-specific nucleotide phosphodiesterase genes in human and mouse. Genes DPDE1, DPDE2, DPDE3, and DPDE4 that share sequence homology with the Drosophila dunce gene were assigned to human chromosome 19 (DPDE1 and DPDE2), 5q12 (DPDE3), and 1p31 (DPDE4) and to mouse chromosomes 8, 9, 13, and 4, respectively. The high-affinity cAMP-specific phosphodiesterase gene (HCP1) was mapped to human chromosome 8q13-q22. Since these genes are potential candidates for involvement in psychiatric or behavioral disorders, knowledge of their chromosomal localizations will facilitate the discovery of their association with disease genes as they are being mapped by linkage studies.

The CAAX farnesyltransferase is a heterodimeric enzyme that attaches a farnesyl group to a single cysteine in several cellular proteins. Substrates include the p21ras proteins, nuclear lamins, and several retinal proteins, all of which end with a "CAAXbox," where C is cysteine, A is an aliphatic amino acid, and X is methionine or serine. Full-length cDNAs for the alpha and beta subunits of the rat farnesyltransferase have been cloned, and both have been shown to be essential for catalytic activity. Here we have used the rat cDNAs to clone cDNAs for the human alpha and beta subunits. Comparison of the human and rat amino acid sequences revealed a remarkable degree of conservation (93% identity for the alpha subunit and 96% identity for the beta subunit). The functional genes for the alpha and beta subunits of human farnesyltransferase (gene symbols, FNTA and FNTB) were localized to human chromosome bands 8p22-q11 and 14q23-q24, respectively, by Southern blot hybridization and PCR analyses of panels of human x Chinese hamster somatic cell hybrid lines and by fluorescence chromosomal in situ hybridization. We also found several related farnesyltransferase genes. FNTAL1 was assigned to 11q13.4-q14.1, FNTAL2 to chromosome 13, and FNTBL1 to chromosome 9.

Radixin is a cytoskeletal protein that may be important in linking actin to the plasma membrane. Recent cloning of the murine and porcine radixin cDNAs revealed a protein highly homologous to ezrin and moesin. The authors have cloned and sequenced the human radixin cDNA and found the predicted amino acid sequence for the human protein to be nearly identical to those predicted for radixin in the two other species. By Southern analyses of Chinese hamster x human somatic cell hybrid DNA and of PCR products derived from hybrids, the coding gene (RDX) was mapped to 11q. Fluorescence chromosomal in situ hybridization with a cDNA plasmid further localized this gene to band 11q23. However, PCR amplification with [open quotes]radixin-specific[close quotes] primers on the hybrid DNA panel yielded an additional, very similar DNA sequence that was further characterized by direct sequencing of PCR products. This sequence represents a truncated version and the respective locus (RDXP2) was assigned to Xp21.3. Furthermore, by employing a different set of primers, a third sequence was found that was 90% identical to the radixin sequence but contained termination codons and seemed to lack introns. This pseudogene (RDXP1) was mapped to 11p by Southern and PCR analyses. 40more » refs., 5 figs., 3 tabs.« less

Hepatocyte nuclear factor-1 alpha (HNF-1 alpha; gene symbol, TCF1) forms dimers with itself as well as with HNF-1 beta and regulates the expression of several liver-specific genes. Recently, a dimerization cofactor of hepatocyte nuclear factor-1 alpha, called DCOH, has been identified. Here, we report the chromosomal localization of the genes for this cofactor to chromosomes 10 in both humans and mice by Southern blot analyses of somatic cell hybrids.

Translocations involving chromosome band 11q23 in acute leukemias have recently been shown to involve the HRX gene that codes for a protein with significant similarity to Drosophila trithorax. HRX gene alterations are consistently observed in t(4;11) (q21;q23)-carrying leukemias and cell lines by Southern blot analyses and are accompanied by HRX transcripts of anomalous size on Northern blots. HRX-homologous cDNAs were isolated from a library prepared from t(4;11)-carrying acute leukemia cells. cDNAs representative of transcription products from the derivative 11 chromosome were shown to contain HRX sequences fused to sequences derived from chromosome band 4q21. Fragments of the latter were used to clone and analyze cDNAs for wild-type 4q21 transcripts that predicted a 140-Kd basic protein (named FEL) that is rich in prolines, serines, and charged amino acids. FEL contains guanosine triphosphate-binding and nuclear localization consensus sequences and uses one of two possible 5' exons encoding the first 12 or 5 amino acids. After t(4;11) translocations, 913 C-terminal amino acids of FEL are fused in frame to the N-terminal portion of HRX containing its minor groove DNA binding motifs. These features are similar to predicted t(11;19) fusion proteins, suggesting that HRX consistently contributes a novel DNA-binding motif to at least two different chimeric proteins in acute leukemias.

The prominent role of the CD40 receptor in B cell responses led us to investigate the role of the gp39-CD40 interaction in a group of primary immunodeficient patients with defective antibody production. Here we report that patients with hyper-IgM syndrome (HIM) have a defective gp39-CD40 interaction. B cells from HIM patients express functional CD40, but their T cells do not bind CD40-Ig. These patients expressed normal levels of gp39 mRNA, but these mRNAs encode defective gp39 proteins owing to mutations in the extracellular domain of gp39. Soluble recombinant forms of gp39 containing these mutations were unable to bind CD40 and drive normal B cell proliferation. The gene encoding gp39 was mapped to Xq26, the X chromosome region where the gene responsible for HIM had previously been mapped. These data suggest that a defect in gp39 is the basis of X-linked HIM.

Dystroglycan is a novel laminin binding component of the dystrophin-glycoprotein complex which provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. Here we report the cDNA and genomic structure of human dystroglycan. The human dystroglycan is encoded by a single gene (DAG1) mapped to chromosome 3 band p21. The coding sequence is organized into two exons, separated by a large intron. The predicted amino acid sequence of human and rabbit dystroglycan are 93% identical with predicted glycosylation sites being conserved. Human dystroglycan is expressed in a variety of fetal and adult tissues. Our data suggest that muscle and non-muscle isoforms of dystroglycan differ by carbohydrate moieties but not protein sequence. Therefore, we hypothesize that variable glycosylation of the conserved protein core might modulate laminin binding. The relationship of dystroglycan to human diseases is discussed.

Subunit VIIa of mammalian cytochrome c oxidase (COX; EC 1.9.3.1) exists in at least two isoforms, one present in all tissue types (‘liver’ isoform; COX VIIa-L) and the other specific for cardiac and skeletal muscle (COX VIIa-M). We have isolated a full-length cDNA encoding human COX VIIa-M. The deduced polypeptide represents the human ortholog of COX VIIa-M, as it shares 78% identity with bovine COX VIIa-M, but only 63% identity with human COX VIIa-L. Northern-blot analysis of primate tissues demonstrated that COXVIIa-M mRNA is present only in muscle tissues; in contrast, the COXVIIa-L mRNA is present in both muscle and nonmuscle tissues. Southern-blot hybridization of human-rodent cell hybrid genomic DNA indicates that the COXVHa-M gene maps to a single locus on chromosome 19, designated COX7AM. In contrast, COXVIIa-L cDNA probes hybridized to fragments from two COX7AL loci, on chromosomes 4 and 14.

Cyclins play an important role in cell cycle regulation. At least five classes of cyclins have been identified--A, B, C, D, and E. B cyclins are generally of two types in most organisms--B1 and B2. We have mapped the gene for human cyclin B1 (CCNB1) to human chromosome 5 (region q13-qter) by Southern blot analysis of human x Chinese hamster somatic cell hybrid panels. Many more cyclin B-related sequences have been identified in the mouse (Cycb-1 to Cycb-10) and have been mapped to chromosomes 4, 5, 7, 8, 13, 14, 15, and 17. Based on our mapping of human CCNB1 and known evolutionary conservation of chromosomal regions, we propose that the homologous cyclin B1 locus, Cycb-4, on mouse chromosome 13 is a functional gene.

LEF-1 is a 54-kDa nuclear protein that is expressed specifically in pre-B and T-cells. It binds to a functionally important site in the T-cell receptor α enhancer and contributes to maximal enhancer activity. LEF-1 is a member of a family of regulatory proteins that share homology with the high mobility group protein 1 (HMG1). The location of the LEF1 gene on human and mouse chromosomes was determined by Southern blot analysis of DNA from panels of interspecies somatic cell hybrids using a murine cDNA probe. Human-specific DNA fragments were detected in all somatic cell hybrids that retained the human chromosomal region 4cen-q31.2. Fluorescent in situ hybridization with two biotin-labeled overlapping human genomic cosmids revealed a specific hybridization signal at 4q23-q25. The homologous locus in the mouse was mapped to chromosome 3 by Southern analysis of rodent × mouse hybrid cell DNA. This chromosomal location was confirmed by the use of a restriction fragment length polymorphism (RFLP) in recombinant inbred mouse strains. The results of this RFLP analysis indicated that the mouse Lef-1 gene was closely linked to Pmv-39 and Egf and was likely placed between these loci, both of which were previously mapped to distal mouse chromosome 3. Our mapping results did not suggest involvement of this gene in previously mapped genetic disorders or in known neoplasia-associated translocation breakpoints.

The enzyme steroid 5 alpha-reductase catalyzes the conversion of testosterone into the more powerful androgen, dihydrotestosterone. We previously described the cloning of rat and human cDNAs that encode steroid 5 alpha-reductase and their expression in oocytes and cultured cells. Here, we report the isolation, characterization, and chromosomal mapping of two human steroid 5 alpha-reductase genes. One gene (symbol SRD5A1) is functional, contains five exons separated by four introns, and maps to the distal short arm of chromosome 5. Two informative restriction fragment length polymorphisms are present in exons 1 and 2 of this gene. A second gene (symbol SRD5AP1) has all of the hallmarks of a processed pseudogene and was mapped to the q24-qter region of the X chromosome. In the mouse, a single steroid 5 alpha-reductase gene (Srd5 alpha-1) is linked to Xmv-13 on chromosome 13.

Thirty cases of endometrial malignancy were successfully studied cytogenetically. Twenty-four of the cases were endometrial adenocarcinomas. Twenty-three of these were stage I tumors, and the twenty-fourth was a stage IV tumor. Fourteen of the stage I adenocarcinomas had abnormal chromosomes, and nine had apparently normal chromosomes. No two tumors had an identical chromosomal rearrangement. Trisomy 1q was common however; 10 of the 14 tumors with abnormal chromosomes had a chromosome 1 abnormality. Clinical and pathologic data were available for 17 of these patients. There appeared to be no relationship between prognostic indicators and the tumor karyotype except for uterine size. Six cases of endometrial malignant mixed mullerian tumor (MMMT) of the homologous type were also analyzed cytogenetically. Three of these tumors had very abnormal karyotypes, and the remaining three had apparently normal chromosomes. Structural abnormalities of chromosome 1, 3, and 5 were present in all three tumors with abnormal karyotypes, but identical breakpoints or rearrangements were not observed.

There is a well-known association between neurofibromatosis-1 (NF1) and Noonan syndrome-like manifestations, including short stature, short broad neck, and hypertelorism. These anomalies are thought to be due to variable expression of the NF1 gene. We report on two girls with NF1 who were found to have the Ullrich-Turner syndrome. Case 1, a 12-year-old white girl, was followed in a Neurofibromatosis Clinic because of multiple cafe-au-lait spots and a family history of NF1 in her mother and sister. On examination, she had short stature, hypertelorism, and short neck with low posterior hairline. Karyotype was 86% 46,XY/14% 45,X. Case 2, the first child of a woman with NF1, presented at birth with lymphedema of hands and feet and a short broad neck. Karyotype was 45,X. At age 23 months she was short, had epicanthic folds, hypertelorism, narrow palate, right simian crease, 19 cafe-au-lait spots, and axillary freckling. We conclude that chromosome studies should be performed in girls with NF1 who have short stature and Noonan- or Ullrich-Turner-like findings. Dilemmas raised by the dual diagnoses of NF1 and Ullrich-Turner syndrome include potential risks of growth hormone therapy and estrogen replacement therapy.

The mammalian aromatic hydrocarbon receptor (AHR) is a ubiquitous ligand-activated transcription factor. AHR ligands include 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin), benzo[a]pyrene, and polychlorinated and polybrominated biphenyls; the endogenous ligand is not yet known. Following ligand binding, the AHR transcriptionally activates genes encoding drug-metabolizing enzymes important in both the metabolic potentiation of substrates to genotoxic reactive intermediates and ultimate carcinogens, and the detoxification of toxic or carcinogenic drugs and other environmental pollutants. AHR-mediated gene expression is also involved in many critical life processes (e.g. cell type-specific differentiation, cell division, apoptosis) by signal transduction mechanisms. Similar to mice, human populations exhibit a > 20-fold range of the CYP1A1 inducibility/AHR affinity phenotype. In the present study, we localized the human AHR gene to chromosome 7p15, using fluorescence in situ hybridization (FISH). Performing linkage analysis in a three-generation family, we show with good probability that the high CYP1A1 inducibility phenotype segregates with the 7p15 region. Sequencing 93 nt (31 amino acids) of the human AHR gene's exon 9, which is the region correlated with the mouse A375V polymorphism responsible for the major portion of high vs low CYP1A1 inducibility/AHR affinity, we found no nucleotide differences; Val-381 was present in all five individuals examined (four related and one unrelated), two of whom show "high' and three of whom show "low' CYP1A1 inducibility. These data indicate that the "high' and "low' CYP1A1 inducibility trait, in the population studied, cannot be explained by a difference among these 31 amino acids in exon 9 of the AHR gene.

Murine B lymphocytes, adipocytes, and olfactory neurons contain a DNA-binding protein that participates in the regulation of genes encoding tissue-specific components of signal transduction. Purification and cloning of this protein, termed early B-cell factor (EBF), from murine B lymphocytes and independent cloning of a protein, termed Olf-1, from olfactory neuronal cells revealed virtual complete amino acid sequence identity between these proteins. As a first step towards identifying a human genetic disorder or mouse mutation for which EBF could be a candidate gene, we have chromosomally mapped the corresponding locus in both species. By Southern hybridization analyses of somatic cell hybrid panels with murine cDNA probe, fluorescence chromosomal in situ hybridization (FISH) of human genomic clones, and analysis of recombinant inbred mouse strains, we have found single sites for EBF homologous sequences on human Chromosome (Chr) 5, band q34, and on proximal mouse Chr 11, in an evolutionarily conserved region.

Moesin is a member of a recently discovered family of closely related proteins that includes ezrin, radixin, and merlin. It is widely expressed in different tissues and cells and has been localized to filopodia and other membranous protrusions that are important for cell-cell recognition and signaling and cell movement. Here, we have localized the coding gene (MSN) to Xq11.2-q12 by Southern and Western blot analyses of Chinese hamster × human somatic cell hybrids and by fluorescence chromosomal in situ hybridization. Moesin-like sequences were identified on chromosomes 5 and 6. The murine Msn locus was mapped to the X chromosome as well by studying a rodent × mouse hybrid panel. The structure of the human moesin gene has been determined. The 12 exons are distributed over >30 kb, and the exon/intron junctions demarcate individual highly conserved domains. Primer extension analysis revealed two major start transcription sites, 184 and 133 bp upstream of the initiation codon. The 5′-flanking region is GC-rich, lacks a TATA box, and contains four SP1 and one AP1 binding sites.

We have generated a line of transgenic mice that when homozygous for the transgene develop a severe, adult-onset neuromuscular disorder. This mutation is likely the result of the insertional inactivation of an endogenous gene by the transgene integration. The mutant mice have a gait abnormality with stiffened and/or splayed hind legs, and adopt a hunched posture with some exhibiting kyphosis of the thoracic spine. These symptoms progress gradually to severe motor dysfunction. Pathologic changes were found in skeletal muscle and peripheral nerve of the mutant animals. In young mice the muscles from both upper and lower extremities show necrosis and phagocytosis. In older mice, regeneration with muscle fiber splitting, internally located nuclei, and variable fiber size are conspicuous features. Interactions between Schwann cells and axons also appear disrupted in these animals. Although many peripheral axons are well myelinated, the nerve and nerve roots contain very large bundles of juxtaposed, bare axons, reminiscent of Schwann cell-axon interactions in early development. Within these bundles there are axons large enough to be myelinated. The relationship between the pathologic changes in the muscles and nerves is not clear. The phenotypic abnormalities of these animals resemble those that occur in the spontaneous mouse mutants dystrophia muscularis and myodystrophy. Nevertheless, the chromosomal position of the transgene integration site, which was mapped by fluorescent in situ hybridization to chromosome 11, indicates that this disorder represents a new neuromuscular mutation.

In the mammalian nervous system, serotonin (5-hydroxytryptamine) binds to distinct cell surface receptor subtypes that are defined by their ligand binding and effector-coupling properties. The 5HT1c receptor is a G-protein coupled receptor that stimulates phospholipase C-catalyzed hydrolysis of phosphatidylinositol bisphosphate, leading to the mobilization of intracellular calcium and to the activation of protein kinase C. By using somatic cell hybrid analysis and FISH, we have mapped the HTR1C locus to the human X chromosome, band q24 and to the mouse X chromosome region D-F4. Comparison of these map positions offers new insights into the evolution of human and murine X chromosomes. Since HTR1C is expressed in certain parts of the central nervous system and abnormal function of the serotoninergic system has been implicated in affective disorders, obsessive-compulsive disorder and epilepsy, establishing the precise map position of HTR1C is an important first step toward evaluating this locus as a candidate for mutations in these syndromes and in X-linked mental disorders.

Two isozymes of steroid 5 alpha-reductase encoded by separate loci catalyze the conversion of testosterone to dihydrotestosterone. Inherited defects in the type 2 isozyme lead to male pseudohermaphroditism in which affected males have a normal internal urogenital tract but external genitalia resembling those of a female. The 5 alpha-reductase type 2 gene (gene symbol SRD5A2) was cloned and shown to contain five exons and four introns. The gene was localized to chromosome 2 band p23 by somatic cell hybrid mapping and chromosomal in situ hybridization. Molecular analysis of the SRD5A2 gene resulted in the identification of 18 mutations in 11 homozygotes, 6 compound heterozygotes, and 4 inferred compound heterozygotes from 23 families with 5 alpha-reductase deficiency. 6 apparent recurrent mutations were detected in 19 different ethnic backgrounds. In two patients, the catalytic efficiency of the mutant enzymes correlated with the severity of the disease. The high proportion of compound heterozygotes suggests that the carrier frequency of mutations in the 5 alpha-reductase type 2 gene may be higher than previously thought.