Disruption and aberrant expression of HMGA2 as a consequence of diverse chromosomal translocations in myeloid malignancies.

Chromosomal translocations that target HMGA2 at chromosome band 12q14 are seen in a variety of malignancies, notably lipoma, pleomorphic salivary adenoma and uterine leiomyoma. Although some HMGA2 fusion genes have been reported, several lines of evidence suggest that the critical pathogenic event is the expression of truncated HMGA2 isoforms. We report here the involvement of HMGA2 in six patients with myeloid neoplasia, dysplastic features and translocations or an inversion involving chromosome bands 12q13-15 and either 7p12, 8q22, 11q23, 12p11, 14q31 or 20q11. Breaks within or very close to HMGA2 were found in all six cases by molecular cytogenetic analysis, leading to overexpression of this gene as assessed by RT-PCR. Truncated transcripts consisting of HMGA2 exons 1-2 or exons 1-3 spliced to intron-derived sequences were identified in two patients, but were not seen in controls. These findings suggest that abnormalities of HMGA2 play an important and previously unsuspected role in myelodysplasia.

The GCGGAA gene-regulatory motif of herpes simplex virus type-1 is also found in hepatitis C virus.

We have analyzed the sequence of the 5'-untranslated region of hepatitis C virus from 24 patients with chronic hepatitis C and we found a conserved six-nucleotide motif previously described as a modulator of gene expression.

Exon concatenation to increase the efficiency of mutation screening by DGGE.

For genes that have a substantial number of exons and long intronic sequences, mutation screening by denaturing gradient gel electrophoresis (DGGE) requires the amplification of each exon from genomic DNA by PCR. This results in a high number of fragments to be analyzed by DGGE so that the analysis of large sample sets becomes labor intensive and time consuming. To address this problem, we have developed a new strategy for mutation analysis, lexon-DGGE, which combines the joining of different exons by PCR (also known as lexons) with a highly sensitive technique such as DGGE to screen for mutations. The lexon technique is based on the concatenation of several exons, adjacent or not, from genomic DNA into a single DNA fragment so that this approach could simultaneously be used to check the mutational status of several small genes. To show the feasibility of the approach, we have used the lexon-DGGE technique to analyze all coding exons, intron-exon junctions, noncoding exon 1, and part of the noncoding region of exon 11 of the TP53 gene. The validity and performance of the technique were confirmed by using negative and positive controls for each of the DNAfragments analyzed.

[Prader-Willi syndrome large deletion on two brothers. Is this the exception that confirm the rule?]. / Dos hermanos con síndrome de Prader-Willy por deleción clásica. ¿Es la excepción que confirma la regla?

INTRODUCTION: Prader-Willi syndrome (PWS), a neuroendocrine disorder could be due to: a large paternally derived chromosome deletion of 15q11-13, to maternal uniparental disomy (UPD), or imprinting mutation (IC); amongst this last group five families, with inherited microdeletion encompassing SNRPN were described; in these families excluded a typical large deletion. Families with more than a child with PWS by classic large deletion have not been published. CLINICAL CASES: We report on a family with three children, 2 of which had typical clinical findings of PWS: mental retardation, hypogonadism, hypotonia, hyperphagia, obesity and also strabismus and synophridia; during pregnancy reduced fetal movement was noted. The Fish probes (SNRPN and D15S10), Methylation specific PCR (MPCR), Southern blot and microsatellite markers confirmed in the PWS brothers a large deletion at least of the area comprising between D15S63 and GABRA5. CONCLUSIONS: No previously described cases in the literature reviewed show for PWS brothers due to a classical deletion. Some possible reasons recurrence in this family could be: at random, germinal mosaicism, or abnormalities at gonadal level environmental factors such as hydrocarbon exposing occupations in fathers of PWS patients as has been referred to by different authors. The latter might be an explanation as the father was working from age of 17 and for over 12 years with paints at shipyards exposed to hydrocarbon and others mutagenic substances. We consider it would be important to bear this case in mind when giving genetic counseling.

[Genetic alterations in hematological neoplasias of lymphoid origin: implications for clinical practice]. / Alteraciones genéticas en las neoplasias hematológicas de origen linfoide: implicaciones en la práctica clínica.

The improvement of the conventional cytogenetic techniques, the development of molecular cytogenetics and the application of techniques of molecular biology to genetic analysis have led to an authentic revolution in the knowledge of the processes implied in the development and progression of lymphoid neoplasias. In this way, a great part of the alterations present in malign cells have been characterised, and the genes involved in the transformative process have been established. This has important consequences for the clinical handling of this type of disease and makes possible a more exact diagnosis through a systematisation of the different entities based on their biological characteristics. On the other hand, the introduction of new techniques of analysis, such as real time PCR, will make it possible to monitor the disease quantitatively, making it possible to evaluate response to the different treatments and to establish predictive values for relapses. In the future, all of this knowledge will make it possible to establish genotype-specific therapies and to develop new medicines aimed at the alteration responsible for the malignant process and with less undesired collateral effects.

[Prevalence of CYPD6 mutations in sporadic Parkinson's disease: case-control study]. / Prevalencia de mutaciones CYP2D6 en enfermedad de Parkinson esporádica: estudio caso-control.

Genetic factors seem to play an important role in the development of Parkinson's disease. The degeneration of the sustantia nigra, characteristic of this disease, might be due to the toxic effect of substances derived from cellular metabolism. The CYP2D6 gene codifies for the metabolising enzyme debrisoquie-4-hydroxilase involved in the detoxification of part of these products. The presence of determinate mutations in the gene implies a lack of enzymatic activity and generates the "poor metaboliser" phenotype. By means of the PCR-RFLP technique, the presence of the genetic mutations CYP2D6 3, CYP2D6 4, CYP2D6 6 and CYP2D6 8 has been analysed in a group of 46 patients with PD and in 54 controls, with the aim of studying the possible value of genotype CYP2D6 as a risk factor for Parkinson's disease in the population of Navarra. The alleles CYP2D6 3, 6 and 8 are not represented in the sample studied. We have not obtained a greater presence of CYP2D6 4 mutations in the patients with respect to the controls (30.43% vs. 44.44%). There is no correlation between Parkinson's disease and the presence of CYP2D6 4 mutations (odds ratio 0.55; 95% CI 0.24 to 1.25), in homozygosis (odds ratio 0.38; 95% CI 0.04 to 3.76) or in heterozygosis (odds ratio 0.62; 95% CI 0.27 to 1.44). In conclusion, the genotype CYP2D6 does not constitute a risk factor in PD.

Degree and distribution of variability in the 5' untranslated, E1, E2/NS1 and NS5 regions of the hepatitis C virus (HCV).

Hepatitis C virus (HCV) shows a high degree of variability resulting in many different variants. In this work we described the variability of several subgenomic fragments from the 5' untranslated region (5'-UTR) and E1, E2/NS1 and NS5 regions comparing, for every position, all the sequences published in GenBank v. 88 (July 1995) as well as new sequences obtained in this work. Variability was determined in two ways. First, we analysed the degree and type of substitutions found in these regions. Second, we defined the most variable and conserved segments in each region and compared our prediction with previous studies. Our results confirm that HCV variability changes along the different regions. Although we found four variable domains in the 5'-UTR, this region was the only one to contain conserved domains. Envelope (E1, E2/NS1) and NS5 regions showed high variability throughout; however, we were able to define six and three hypervariable domains, respectively. The degree and distribution of variability established in this work is supported by the high number of sequences and the different types included in the study. Knowledge of how variability is distributed along the different regions of the HCV genome could be of use in the design of new diagnostic and therapeutic strategies against HCV infection.

Variability in the levels of PML-RAR alpha fusion transcripts detected by the laboratories participating in an external quality control program using several reverse transcription polymerase chain reaction protocols.

BACKGROUND AND OBJECTIVES: The detection of PML-RAR by reverse transcription (RT) polymerase chain reaction (PCR) in acute promyelocytic leukemia (APL) patients who are in hematologic remission influences therapeutic decision making in several trials. In the light of this, the Spanish group has recently designed an external quality assessment program (EQAP) of RT-PCR detection of PML-RAR, which includes a study of sensitivity of the participating laboratories. DESIGN AND METHODS: Eighteen laboratories were involved in the program. Ten laboratories followed the method of Biondi et al., 5 employed that of Borrow et al. and the 3 remaining used other protocols. The sensitivity was studied in five rounds of quality control. The first two shipments consisted of dilutions of NB4 RNA into non-APL RNA. The third round consisted of serial dilutions of the NB4 cell line into HL60 cells. The fourth and five rounds consisted of plasmid dilutions containing the bcr1 and bcr3 PML-RAR isoforms. RESULTS: The results showed that the distinct methods allow detection of the PML-RAR hybrid up to a dilution of 10(-4), and exceptionally, up to 10(-5). The laboratories following the method of Biondi et al. usually detected the 10(-3) dilution and less frequently the 10(-4) one, whereas those using other methods usually detected PML-RAR transcript in the 10(-4) dilution, and less commonly in the 10(-5) dilution. However, each of the PCR methods used by EQAP participating laboratories successfully detected at least 50 copies of PML-RAR alpha fusion transcript in plasmid dilution controls. INTERPRETATION AND CONCLUSIONS: The results point to heterogeneous sensitivity amongst participating laboratories. This may reflect differences in methodology, although variations in sample quality may also account for discrepant findings.