Genetic loading in familial migraine with aura.

Migraine with aura (MA) arises from a combination of genetic and environmental factors. The sibling risk, age at onset, and aura type were compared in 54 MA probands categorised by family history of MA. Three family types were ascertained each having an MA proband and: (1) an MA parent and MA offspring (three generation; n=15), (2) either an MA parent or an MA offspring (two generation; n=20), and (3) neither an MA parent nor an MA offspring (one generation; n=19). The crude recurrence risk to siblings of probands was 2.7-fold higher in three generation compared with two generation MA families (chi(2)=6.24, p=0.0125) and 4.8-fold higher in three generation compared with one generation MA families (chi(2)=9.95, p<0.002). The mean age at onset decreased with an increase in genetic load. The MA probands from three generation families were significantly younger than probands from the one generation families (F=5.14, p=0.030). MA probands from three generation families were more likely to report more than one type of aura than MA probands from two generation families (chi(2)=4.44, p=0.035). The significant difference in genetic loading and the earlier age at onset in the three generation families add further evidence for a genetic basis for MA and the difference in sibling risks demonstrates that the MA population is heterogeneous.

Migraine with aura is not linked to the FHM gene CACNA1A or the chromosomal region, 19p13.

Two microsatellite markers, tightly linked to CACNA1A, were genotyped in migraine with aura (MA) families to determine if this gene, which underlies the 19p13 linked forms of familial hemiplegic migraine, is also linked to MA. Two-point parametric lod and nonparametric linkage scores did not support linkage. Transmission disequilibrium testing provided no evidence for linkage of MA to CACNA1A. In a large dataset of 64 Canadian MA families, the authors did not find evidence to support an MA susceptibility gene in the region of 19p13.

Quantitative analysis of multidrug resistance gene expression in human osteosarcomas.

We evaluated the MDR1 expression levels in 77 osteosarcomas and investigated whether MDR1 mRNA expression in osteosarcomas varies with location within the tumour, following chemotherapy, or after metastasis. We modified the semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) assay to determine accurately the levels of MDR1 mRNA expression in clinical specimens. We show that specimens collected from multiple locations in six tumours revealed very little variation in MDR1 expression suggesting that the levels of MDR1 in these tumours do not vary greatly with location within the tumour mass. In a comparison of pre and post-chemotherapy specimens it was found that MDR1 levels did not change appreciably following chemotherapy in 16 of 20 cases. In addition, in eight of ten specimens obtained before and after metastasis, the amount of MDR1 mRNA was found to remain relatively constant despite metastatic spread. Thus, many osteosarcomas exhibited intrinsic expression of MDR1 mRNA before multidrug regimens which invariably included doxorubicin and, in most cases, MDR1 expression was not induced following chemotherapeutic treatment. Our results suggest that some osteosarcoma patients may have primary tumours which are resistant to doxorubicin. These individuals may benefit from different chemotherapeutic regimens, e.g. the addition of MDR reversal agents.

SAS is amplified predominantly in surface osteosarcoma.

The development of several types of human tumors is related to amplification of genes that are involved in cell growth. The protein products of these genes give the cells a selective growth advantage. The q13-15 region of chromosome 12 is frequently altered in human sarcomas, and the SAS gene has been identified in an amplification unit mapping to this region. Gene amplification of SAS was analyzed to determine the frequency of genetic alteration of this gene in osteosarcoma. Using Southern blot analysis as well as quantitative polymerase chain reaction, SAS was found to be amplified in 10 (36%) of 28 osteosarcomas. Gene amplification was evaluated in subtypes of osteosarcoma. All seven surface osteosarcomas displayed amplified SAS. In contrast, SAS was amplified in only two (13%) of 15 intramedullary osteosarcomas. The finding that all surface osteosarcomas demonstrated SAS gene amplification suggests that this gene may play a role in the pathogenesis of osteosarcoma subtypes and that surface osteosarcoma may be genetically different from high-grade intramedullary osteosarcoma.

Expression of the multiple drug resistance gene in human renal cell carcinoma depends on tumor histology, grade, and stage.

Levels of mRNA expressed by the multidrug resistance gene MDR1 were examined in 23 renal cell carcinoma samples and adjacent normal kidney cortex using reverse-transcription PCR. Comparison of MDR1 levels between histological types revealed that there was on average significantly more MDR1 in clear cell tumors than in oncocytomas (0. 89 +/- 0.10 versus 0.28 +/- 0.20, ratio of MDR1 in tumor cells to the drug-resistant cell line KB-8, P < 0.05). The mean MDR1 level of all of the non-oncocytoma tumors was not significantly different from the mean MDR1 level of normal adjacent kidney (0.89 +/- 0.10 versus 1.11 +/- 0.12, P = 0.07). However, the mean MDR1 level of the more undifferentiated clear cell tumors was significantly lower than the mean MDR1 level of adjacent normal kidney (0.74 +/- 0.10 versus 1.11 +/- 0.12, P < 0.05). MDR1 levels in early stage, clear cell tumors (n = 14) were lower than in tumors that had spread into perinephric tissue or had metastasized (n = 6) (0.77 +/- 0.08 versus 1.24 +/- 0.30, P < 0.05). In conclusion, MDR1 expression decreases in the more undifferentiated tumors, but still remains at levels high enough to be drug resistant. Higher MDR1 expression in the invasive tumors compared with noninvasive tumors suggests that MDR1 expression and invasiveness may be linked.

Laryngeal verrucous carcinoma: a clinicopathologic study and detection of human papillomavirus using polymerase chain reaction.

Laryngeal verrucous carcinoma (LVC) is a rare, well-differentiated variant of squamous carcinoma with a low malignant potential. Human papillomavirus (HPV)-16 DNA has been identified in a small number of LVC and an etiologic relationship has been suggested. A correlative clinical and molecular pathological study was performed in order to determine the prevalence and typing of HPV DNA in LVC. Possible associations between patient and tumor subsets, and the presence of HPV DNA were also investigated. Formalin-fixed, paraffin-embedded tissue samples from 29 patients with LVC were examined by polymerase chain reaction (PCR) using DNA primers specific for HPV types 6b/11, 16, and 18. Overall, HPV DNA was detected in 13 (45%) of the cases. Of these, HPV-16 DNA, HPV-18 DNA, and both HPV-16 DNA and HPV-18 DNA were detected in 4 (14% overall; 31% of positive cases), 4, and 5 (17% overall; 38% of positive cases), respectively. HPV-6b/11 DNA was not detected in any LVCs. In 16 cases, no HPV DNA was detected. There was a trend toward HPV DNA detection in higher stage tumors. HPV DNA detection was unrelated to patient age, tumor site, or radiotherapeutic responsiveness. The detection of HPV DNA in 45% of LVCs suggests an association between the presence of HPV-16 DNA and HPV-18 DNA, and some LVCs.

Detection and typing of human papillomavirus in verrucous carcinoma of the oral cavity using the polymerase chain reaction.

OBJECTIVE: This study examined the prevalence and types of human papillomavirus (HPV) DNA in oral cavity verrucous carcinoma. DESIGN: This was of a retrospective screening study. Formalin-fixed, paraffin-embedded tissue samples were examined by the polymerase chain reaction using DNA primers specific for HPV types 6b/11, 16, and 18. SETTING: The majority of patients were seen at referral centers in Ontario, Canada. PATIENTS: This study examined 29 oral cavity verrucous carcinomas occurring in a sample of 25 patients from four institutions between 1966 and 1992. All tumors met standardized histologic diagnostic criteria of verrucous carcinoma. MAIN OUTCOME MEASURE: The prevalence of HPV 6b/11, 16, and 18 DNA was determined by the PCR technique. RESULTS: The HPV DNA was detected in 12 (48%) of 25 patients. The HPV 6b/11 DNA, HPV 16 DNA, HPV 18 DNA, and HPV 16 DNA plus HPV 18 DNA, were detected in one (4%), one (4%), nine (36%), and one (4%) cases, respectively. CONCLUSIONS: The detection of HPV 18 DNA in 40% of oral cavity verrucous carcinomas suggests an association between the presence of HPV 18 DNA and some oral cavity verrucous carcinomas. The etiologic and prognostic significance of HPV 18 for oral cavity verrucous carcinoma remains unanswered and will require further study.

Expression of the homeo box-containing gene En-2 delineates a specific region of the developing mouse brain.

We have examined the pattern of expression of the homeo box-containing gene En-2 during mouse embryogenesis using in situ hybridization. Transcripts were first detected in the neural folds of 8.0-day, 5-somite embryos, and expression continued throughout development into adulthood. Hybridization occurred only in the central nervous system (CNS) and was limited to one band of the neural tube and to parts of those structures that later developed from it; the cerebellum, pons, periaqueductal gray, and colliculi. Expression in the germinal zone of the CNS was uniform within the hybridizing band. However, later in development, once cells had migrated out of the germinal zone, there was a reduction in the extent of hybridization and an increase in its spatial complexity. In the adult, expression of En-2 appeared to be limited to specific groups of neurons. The early, localized expression of En-2 within an apparently homogeneous tissue is consistent with the hypothesis that En-2 plays a role in defining a spatial domain within the developing brain.