Mutations in the activin receptor-like kinase 1 gene in hereditary haemorrhagic telangiectasia type 2.

Hereditary haemorrhagic telangiectasia, or Osler-Rendu-Weber (ORW) syndrome, is an autosomal dominant vascular dysplasia. So far, two loci have been demonstrated for ORW. Linkage studies established an ORW locus at chromosome 9q3; endoglin was subsequently identified as the ORW1 gene. A second locus, designated ORW2, was mapped to chromosome 12. Here we report a new 4 cM interval for ORW2 that does not overlap with any previously defined. A 1.38-Mb YAC contig spans the entire interval. It includes the activin receptor like kinase 1 gene (ACVRLK1 or ALK1), a member of the serine-threonine kinase receptor family expressed in endothelium. We report three mutations in the coding sequence of the ALK1 gene in those families which show linkage of the ORW phenotype to chromosome 12. Our data suggest a critical role for ALK1 in the control of blood vessel development or repair.

PTEN gene mutations are seen in high-grade but not in low-grade gliomas.

The PTEN gene, located on 10q23, has recently been implicated as a candidate tumor suppressor gene in brain, breast and prostate tumors. In the present study, 123 brain tumors, including various grades and histological types of gliomas occurring in children and adults, were analyzed for PTEN mutations by SSCP assay and sequencing. Mutations in the PTEN gene were found in 13 of 42 adult glioblastomas and 3 of 13 adult anaplastic astrocytomas, whereas none of the 21 low-grade adult gliomas or the 22 childhood gliomas of all grades showed mutations. The single medulloblastoma with a mutation was a recurrent tumor that also possessed a p53 mutation. High-grade adult gliomas with PTEN mutations included cases that also contained gene amplification or p53 gene mutations, as well as cases that did not contain either of these abnormalities. There was no obvious relationship between presence of PTEN mutation and survival; however, there was a tendency for PTEN mutations to occur in older age group patients. This analysis suggest that PTEN gene mutations are restricted to high-grade adult gliomas and that this abnormality is independent of the presence or absence of gene amplification or p53 gene mutation in these tumors.

Gastrointestinal pathology in patients with common variable immunodeficiency and X-linked agammaglobulinemia.

Review of the medical records of 43 patients with common variable immunodeficiency (CVID) and 23 patients with X-linked agammaglobulinemia (XLAG) revealed a high incidence of chronic gastrointestinal complaints, most commonly diarrhea. Thirty-eight biopsies, four small-bowel resection specimens, and one autopsy from 10 patients with CVID and one patient with XLAG showed a wide range of abnormalities. A pattern resembling acute graft-versus-host disease, with apoptotic bodies and lymphocytes in crypts, was seen in the stomach (four patients), small bowel (three patients), and colon (three patients). Small-bowel specimens from three CVID patients with malabsorption showed mild to severe villous atrophy. Three CVID patients had Giardia in biopsies. Two cases of small bowel lymphoma associated with nodular lymphoid hyperplasia were identified in CVID patients. One patient's small bowel contained foamy histiocytes in the lamina propria, resembling Whipple's disease or chronic granulomatous disease, with numerous apoptotic bodies in crypts. Ultrastructurally, the histiocytes contained cellular debris. The patient with XLAG had recurrent fissuring necrosis of small bowel resembling Crohn's disease; a patient with CVID had colitis with features similar to ulcerative colitis. Poorly formed granulomas were seen in the stomach (one CVID patient) and the colon (two CVID patients). Lymphocyte populations were dominated by T cells; B cells were scarce except in lymphoid follicles in CVID patients with nodular lymphoid hyperplasia. Patients with CVID and XLAG manifest a spectrum of abnormalities in the gastrointestinal tract, with patterns superficially resembling graft-versus-host disease, inflammatory bowel disease, and Whipple's disease, but often lacking some of the diagnostic features of the diseases. Many of the CVID patients with chronic gastrointestinal complaints (62%) also had evidence of autoimmune phenomena, suggesting that in some patients the inflammatory process in the gastrointestinal tract has an autoimmune component.

The pathology of liver-localized post-transplant lymphoproliferative disease: a report of three cases and a review of the literature.

Post-transplantation lymphoproliferative disease (PTLD) is a complication of solid organ transplantation that is typically of B-cell origin and associated with Epstein-Barr virus (EBV). In patients receiving orthotopic liver transplantation (OLT) and treated with cyclosporin A. PTLD typically presents between 6 and 17 months post-transplantation as a systemic illness with involvement of the hepatic graft in a minority of cases. A small number of cases of biopsy-proven PTLD arising in the hepatic graft and limited to the liver and periportal structures have been previously reported. This report describes three additional cases of liver-localized PTLD and reviews similar cases in the literature. The donor/host origin of PTLD may have prognostic significance because the two cases in this report that are of donor origin had different clinical and pathologic features compared with the case of host origin. A rapid PCR-based technique for determining the origin of PTLD is described.

Evaluation of an automated technique for assessment of marrow engraftment after allogeneic bone marrow transplantation using a commercially available kit.

Several methods have been used to evaluate engraftment after allogeneic bone marrow transplantation (BMT). We assessed the usefulness of a multiple short tandem repeat (STR) amplification kit combined with a capillary electrophoresis unit for DNA identity analysis in the evaluation of engraftment after BMT. For 17 of 18 patients, at least 1 locus showed unique alleles for the donor and the recipient. In all cases, at least 1 locus was informative for the presence of small amounts of recipient DNA. The results from STR analysis were the same as Southern blot analysis in 14 of 17 cases. Differences included mixed chimerism detected only with STR analysis, informative loci present only with STR analysis, and informative loci present only with Southern blot analysis (1 case each). By using mock mixed chimeras, minor populations of 5% were detected routinely in all loci using the kit manufacturer's default protocol. By increasing the amount of amplified DNA, minor populations of 1% were detected in all cases but not in all loci. This single reaction technique provides for faster results, reduced workforce needs, and greater sensitivity than traditional Southern blot.

Translocation (15;17)(q22;q21) as a secondary chromosomal abnormality in a case of acute monoblastic leukemia with tetrasomy 8.

We describe a case of acute monoblastic leukemia (AML M5a), originally presenting as granulocytic sarcoma of the testis, showing unusual cytogenetic abnormalities. Tetrasomy 8 (primary) and t(15;17)(q22;q21) (secondary) were detected in bone marrow cells 6 months post-diagnosis, both by routine karyotype analysis and by fluorescence in situ hybridization (FISH) studies on metaphases and interphase nuclei. Retrospectively, the same abnormalities were identified in the primary testicular lesion using interphase FISH. However, reverse transcriptase polymerase chain reaction (RT-PCR) did not reveal the presence of a classic PML/RAR alpha fusion transcript. To the best of our knowledge, this is the first case to be reported in the literature of AML showing tetrasomy 8 in combination with secondary t(15;17).

Cytogenetic and molecular analysis of an unusual case of acute promyelocytic leukemia with a t(15;17;17)(q22;q23;q21).

We present a 52-year-old female with a clinical history of acute myelocytic leukemia, probable acute promyelocytic leukemia (APL). Flow cytometry results were somewhat unusual. Specifically, the promyelocytic population showed partial positivity for antigens not usually expressed in APL (HLA-DR and CD117). The interpretation of these results was that the abnormal population contained a proportion of very early promyeolocytes that had not completely lost all their "precursor" antigens. Cytogenetic analysis of a bone marrow aspirate showed a t(15:17;17)(q22;q23;q21) in all cells analyzed. Fluorescence in situ hybridization (FISH) analysis using the PML-RARA DNA probe showed a positive signal pattern (fusion) in 100% of 200 total interphase and metaphase cells examined, confirming the presence of the PML-RARA rearrangement. Multicolor FISH, which produces 24 colors to differentiate all chromosomes in a single hybridization, was applied. This study confirmed the cytogenetic interpretation of the rearrangement. No material from any other chromosome was detected on the second smaller derivative chromosome 17. Additional studies using the RARA(17q21) break-apart DNA FISH probe showed that 17q21 (RARA) was not rearranged on the derivative chromosome 17 that received the q22-->qter segment from chromosome 15. The RARA locus on the smaller derivative 17 was the allele involved in the fusion in this three-way rearrangement. The signal pattern was consistent in 100% of interphase and metaphase cells scored. This unusual t(15;17;17) prompted us to investigate further using reverse-transcription polymerase chain reaction with primers from the 3' and 5' regions of both the RARA and PML loci. These studies showed that the PML-RARA fusion was present, but the complementary fusion RARA-PML, which is usually detectable, was absent. The patient is responding well to standard treatment protocols.

Cooperativity at a distance promoted by the combined action of two replication initiator proteins and a DNA bending protein at the replication origin of pSC101.

We have investigated the interaction of the host-encoded DNA bending protein IHF, the host-encoded initiator DnaA, and the plasmid-encoded initiator RepA with the replication origin of pSC101. We have discovered that DNA bending induced by IHF in vitro promoted the interaction of DnaA protein with two physically separated binding sites called dnaAs and dnaAw. This cooperative interaction at a distance, most probably, caused looping out of the ihf site. We have also discovered that RepA protein binding to its cognate sites promoted enhanced binding of DnaA protein to the physically distant dnaAs site, probably also by DNA looping. The addition of RepA to a binding reaction containing IHF and DnaA further enhanced the binding of DnaA protein to the dnaAs site. Thus, the three DNA-binding proteins interacted with the origin, generating a higher order structure in vitro. On the basis of the results of the known requirement of all three proteins for replication initiation, we have proposed a model for the structure of a preinitiation complex at the replication origin.

The integration host factor of Escherichia coli binds to bent DNA at the origin of replication of the plasmid pSC101.

The integration host factor (IHF) of Escherichia coli is necessary for maintenance of pSC101. The protein binds specifically to the replication origin of the plasmid, in the AT-rich region located immediately adjacent to the left, weak binding site for the plasmid-encoded initiator protein. DNAase I and OH- radical footprinting experiments showed that IHF protects 49 bp of the DNA at the origin region. Methylation protection analyses revealed that IHF contacts purine residues in both the major and minor grooves of the DNA. Electrophoretic analyses showed that IHF binds to bent DNA, and the protein binding further enhances the degree of DNA bending. Site-directed mutagenesis of three of the contact points not only abolished binding of the protein to the DNA but also inactivated the replication origin. Therefore, binding of IHF to the ori sequence most probably is necessary for initiation of plasmid replication.

Replication of plasmid R6K origin gamma in vitro. Dependence on dual initiator proteins and inhibition by transcription.

We have developed a more efficient in vitro replication system for the plasmid R6K with the objective of dissecting the mechanism of activation of replication origins at a distance. Using this in vitro system we have shown that the activation of replication origin gamma of R6K is absolutely dependent on two exogenously added initiator proteins: namely the host-encoded DnaA and the plasmid-encoded Pi proteins. Replication was inhibited by novobiocin, suggesting a requirement for DNA gyrase. Surprisingly, rifampicin stimulated in vitro replication significantly, and this stimulation was manifested in the quantitative enhancement of replication without any noticeable qualitative change in the reaction products. This result suggests that transcription at or near the gamma origin keeps it repressed. Replication intermediates that were allowed to accumulate by dideoxynucleoside triphosphate incorporation were analyzed both by restriction enzyme digestion and by electron microscopy, and both sets of analyses revealed initiation from the gamma origin resulting in theta-type replication intermediates. Further development of this system should help us to understand how DNA-protein interaction at the gamma origin/enhancer activates the distal origins alpha and beta.

Multiple myeloma-associated amyloidosis and giant cell arteritis.

Primary systemic amyloidosis has been associated with the development of symptoms and clinical features characteristic of polymyalgia rheumatica and/or giant cell arteritis (GCA). Case reports of this clinical entity have been published, stating that the amyloid deposition leads to the symptoms of vasculitis. In this report, we present a second case in the English literature of a patient presenting with multiple myeloma-associated amyloidosis and GCA. This is the first case in which the histopathologic findings are described in enough detail to suggest a pathogenic relationship between the two diseases.

Quality control in molecular genetic testing.

DNA-based testing for genetic diseases has developed from nothing into a principal part of laboratory medicine over the past 15 years. In the rush to bring these powerful new technologies into medical use, issues of quality have not always been given sufficient attention. Efforts are now being made to assess the quality of the output of genetic testing laboratories, and the results show that there is room for improvement.

NMR studies of combined lanthanide shift and relaxation agents for differential characterization of 23Na in a two-compartment model system.

Spin relaxation and chemical shifts by lanthanide chelate complexes are used to distinguish 23Na signals in a simulated two-compartment model. Both effects are significant in EDTA, DTPA, and TPP complexes of Gd and in the TPP complex of Dy. The simultaneous measurement of these properties is illustrated and represents a promising method for monitoring sodium concentrations and fluxes including fast transport components.

Successful allogeneic engraftment of mismatched unrelated cord blood following a nonmyeloablative preparative regimen.

Reduction in the toxicity of allogeneic transplantation with nonmyeloablative induction regimens has expanded the scope of practice to older and more debilitated patients. However, the limited availability of matched sibling donors requires that alternative donor sources be investigated. Reported here are 2 cases of patients with advanced hematologic malignancies without matched siblings, partially matched family members, or matched unrelated donors who successfully underwent nonmyeloablative conditioning therapy followed by infusion of partially matched, unrelated-donor cord blood cells. The patients are in remission and remain 100% donor as assessed by short tandem repeat analysis of the marrow 6 and 12 months following transplantation.

The activin receptor-like kinase 1 gene: genomic structure and mutations in hereditary hemorrhagic telangiectasia type 2.

The activin receptor-like kinase 1 gene (ALK-1) is the second locus for the autosomal dominant vascular disease hereditary hemorrhagic telangiectasia (HHT). In this paper we present the genomic structure of the ALK-1 gene, a type I serine-threonine kinase receptor expressed predominantly in endothelial cells. The coding region is contained within nine exons, spanning < 15 kb of genomic DNA. All introns follow the GT-AG rule, except for intron 6, which has a TAG/gcaag 5' splice junction. The positions of introns in the intracellular domain are almost identical to those of the mouse serine-threonine kinase receptor TSK-7L. By sequencing ALK-1 from genomic DNA, mutations were found in six of six families with HHT either shown to link to chromosome 12q13 or in which linkage of HHT to chromosome 9q33 had been excluded. Mutations were also found in three of six patients from families in which available linkage data were insufficient to allow certainty with regard to the locus involved. The high rate of detection of mutations by genomic sequencing of ALK-1 suggests that this will be a useful diagnostic test for HHT2, particularly where preliminary linkage to chromosome 12q13 can be established. In two cases in which premature termination codons were found in genomic DNA, the mutant mRNA was either not present or present at barely detectable levels. These data suggest that mutations in ALK-1 are functionally null alleles.

Molecular genetic aspects of oligodendrogliomas including analysis by comparative genomic hybridization.

Oligodendroglial neoplasms are a subgroup of gliomas with distinctive morphological characteristics. In the present study we have evaluated a series of these tumors to define their molecular profiles and to determine whether there is a relationship between molecular genetic parameters and histological pattern in this tumor type. Loss of heterozygosity (LOH) for 1p and 19q was seen in 17/23 (74%) well-differentiated oligodendrogliomas, in 18/23 (83%) anaplastic oligodendrogliomas, and in 3/8 (38%) oligoastrocytomas grades II and III. LOH for 17p and/or mutations of the TP53 gene occurred in 14 of these 55 tumors. Only one of the 14 cases with 17p LOH/TP53 gene mutation also had LOH for 1p and 19q, and significant astrocytic elements were seen histologically in the majority of these 14 tumors. LOH for 9p and/or deletion of the CDKN2A gene occurred in 15 of these 55 tumors, and 11 of these cases were among the 24 (42%) anaplastic oligodendrogliomas. Comparative genomic hybridization (CGH) identified the majority of cases with 1p and 19q loss and, in addition, showed frequent loss of chromosomes 4, 14, 15, and 18. These findings demonstrate that oligodendroglial neoplasms usually have loss of 1p and 19q whereas astrocytomas of the progressive type frequently contain mutations of the TP53 gene, and that 9p loss and CDKN2A deletions are associated with progression from well-differentiated to anaplastic oligodendrogliomas.

Mutation and expression analysis of the endoglin gene in hereditary hemorrhagic telangiectasia reveals null alleles.

Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder characterized by multisystemic vascular dysplasia and recurrent hemorrhage from the sites of vascular lesions. Two genes have been identified for HHT. Endoglin, a TGF-beta binding protein which maps to chromosome 9q3, is the gene for HHT1. The type and location of most of the previously described mutations in the endoglin (ENG) gene suggested a dominant-negative model of receptor-complex dysfunction for the molecular basis of this disorder. In this article we describe 11 novel ENG mutations in HHT kindreds, which include missense and splice-site mutations. Two identical missense mutations in unrelated families disrupt the start codon of the gene. In addition, some frameshift and nonsense mutations lead to very low or undetectable levels of transcript from the mutant allele. These combined data suggest that the nature of most ENG mutations is to create a null (nonfunctional) allele, and that there is no requirement for the synthesis of a truncated endoglin protein in the pathogenesis of HHT.