A patient with juvenile Huntington's disease (HD) of probable maternal inheritance is reported. The expanded IT-15 allele was only detected with the use of modified PCR and Southern transfer techniques, which showed a CAG trinucleotide repeat expansion of approximately 250 repeats-the largest CAG expansion reported within the huntingtin gene. This case emphasizes the need for communication between the diagnostic laboratory and the clinician to define the molecular genetics of unusual cases.

Recently we molecularly cloned and characterized a papillomavirus from a lymph node metastasis of a primary penile carcinoma found in a rhesus monkey; this virus species, rhesus papillomavirus type 1 (RhPV-1), is similar to oncogenic human papillomaviruses (HPVs), such as HPV-16 or HPV-18, in that the RhPV-1 DNA was found to be integrated in the tumor cell DNA. To compare the sexual transmission and oncogenic nature ofRhPV-1 with these HPVs, we undertook an extensive retrospective study of a group of rhesus monkeys whose sexual mating and offspring histories were known. These animals had mated directly with the index male mentioned above or were secondarily exposed to this virus through intermediate sexual partners. This study combines cytological, histopathological, and several complementary hybridization and DNA amplification techniques on multiple tissue samples to demonstrate the sexually transmitted nature of RhPV-1. The oncogenic potential of RhPV-1 is suggested in several of the infected animals by the presence of various degrees of neoplasia including squamous cell cancer of the cervix.The compelling evidence that certain types of human papillomavirus (HPV) are associated with malignancies of the anogenital tract has been based largely upon the detection of HPV DNA in various tissues (for review, see ref.

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Background: Molecular diagnostics devices are becoming smaller. With the advancement of miniaturization technologies, microchip-based systems will soon be available for genetic testing. The purpose of this review is to highlight the underlying principles in miniaturization, the strategies being developed for bioanalysis, and the potential impact on the practice of this rapidly growing medical discipline. Approach: The author discusses DNA microchips and their practical importation into the clinical laboratory, based on his background in medical device and microchip design and development. His discussion is supported by a body of literature covering both biomedical and electrical engineering and more recent publications in the field of molecular genetics and pathology. Content: This review is descriptive and intended to outline the technologic and methodologic approaches to the creation of an integrated genetic analysis instrument based on miniature components. The review draws on published scientific evaluations of these devices without regard to the companies involved in their development. Summary: The intent of this review is that the reader will better understand the variety of technical approaches toward the miniaturization of molecular genetic testing for the clinical laboratory. With insight into the principles underlying the operation of these chips and the integrated systems, the end user can better evaluate the value to the field in terms of making molecular genetics testing simpler, faster, and less expensive.

Bone marrow biopsy is the conventional staging and posttherapy evaluation method for assessing marrow involvement by lymphoma. Polymerase chain reactions (PCR) for antigen receptor rearrangements have the potential to increase the detection of minimal degrees of marrow involvement. The present study is a concurrent morphologic and PCR evaluation of 225 staging or posttherapy marrow biopsies from 127 patients with B-lineage non-Hodgkin's lymphoma. The biopsies were morphologically categorized into four groups: group 1 (positive for lymphoma), 60 biopsies (27%); group 2 (suspicious for lymphoma), 20 biopsies (9%); group 3 (lymphocytic lesions of indeterminate biology), 22 biopsies (10%); and group 4 (negative for lymphoma), 123 biopsies (54%). Molecular studies were performed on concurrently obtained aspirates and used consensus immunoglobulin-heavy-chain (IgH) and IgH/bcl-2 gene PCR primers. A molecular clone was detected in 53 of the 225 aspirates (24%): group 1, 34 aspirates (57%); group 2, five aspirates (25%); group 3, one aspirate (5%); and group 4, 13 aspirates (11%). A PCR-positive aspirate was present in 47% of follicular lymphomas, 58% of diffuse large cell lymphomas, and 72% of the other lymphomas in the group I specimens. Morphology or PCR was positive in 79 of the 225 cases (35%). The molecular detection of clonality in the aspirate DNA from cases with positive morphologic findings was lower than anticipated. The discordance between morphology and PCR results may be related to sample variation between the trephine biopsy and aspirate, a failure to aspirate sufficient lymphoma cells, or insufficient primer homology for amplification. DNA extracted from trephine sections may provide results more concordant with morphology, because PCR detected a clone in 10 of 11 DNA specimens extracted from trephine biopsies with positive morphologic findings and PCR negative aspirates.

T-cell non-Hodgkin's lymphomas are an uncommon occurrence after solid-organ transplantation. We describe a morphologically and immunophenotypically distinct group of T-cell lymphoproliferative disorders that occurred late in the course of six patients with solid-organ transplants. The patients ranged in age from 31 to 56 years (median, 43). Three were male; all were splenectomized. The interval from transplant to the diagnosis of lymphoma ranged from 4 to 26 years (median, 15). Symptoms at presentation were related to sites of involvement. Pulmonary, marrow, and CNS involvement were present in five, four, and one case, respectively. No patient had lymphadenopathy. Five patients had an elevated lactate dehydrogenase level (range, 226 to 4,880 IU/L; median, 1,220 IU/L). Five of six patients had a leukoerythroblastic reaction. All cases had large-cell histology and frequently contained cytoplasmic granules. Those cases tested expressed CD2, CD3, and CD8 and were negative for B-cell antigens. T-cell receptor beta- and gamma-chain genes were clonally rearranged in three of three and one of three cases, respectively. All T-cell posttransplant lymphoproliferative disorders (T-PTLDs) studied were negative for Epstein-Barr virus (EBV), human T-cell leukemia/lymphoma virus type 1 (HTLV-1), human T-cell leukemia/lymphoma virus type 2 (HTLV-2), and human herpes virus type 8 (HHV-8) genomes. Treatment with acyclovir (three patients) or chemotherapy (three patients) resulted in two responses. All patients had an aggressive course, with a median survival duration of 5 weeks. In conclusion, a clinically aggressive T-PTLD may be a late complication of solid-organ transplantation and does not appear to be related to EBV, HTLV-1, HTLV-2, or HHV-8 infection.

To study prognostic factors in infant acute myeloid leukemia (AML), we analyzed 44 children treated on Childrens Cancer Group protocols for MLL gene rearrangement by Southern blot, cytogenetic 11q23 abnormalities, and reactivity with monoclonal antibody 7.1. This antibody detects the human homologue of the rat NG2 chondroitin sulfate proteoglycan molecule, which has previously been reported to be expressed on human melanoma. NG2 has been found to be expressed on human leukemic blasts but not on other hematopoietic cells. In childhood AML, NG2 cell surface expression correlated with poor outcome and with some but not all 11q23 rearrangements. In childhood acute lymphoblastic leukemia, NG2 expression correlated with poor outcome and with balanced 11q23 translocations. In this study, 29 of 44 (66%) of infants with AML showed MLL rearrangement and, as expected, this group had a high incidence of French-American-British M4/M5 morphology (22/29). Of the cases tested, 35.1% (13/37) were NG2 positive. All (13/13) NG2-positive cases were rearranged at MLL, whereas only 46% (11/24) of NG2-negative cases had MLL rearrangement. NG2 expression did not correlate with poor outcome (P = .31); there was a trend towards a worse outcome with MLL rearrangement (P = .13). Thus monoclonal antibody 7.1 does not detect all cases of MLL rearrangement in infant AML.

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