Identificación de mutaciones y diagnóstico molecular de portadoras en familias mexicanas con distrofia muscular Duchenne/Becker

Introducción: La Distrofia muscular de Duchenne/Becker (DMD/BMD) es la miopatía hereditaria más frecuente en las poblaciones humanas. Se caracteriza por una debilidad muscular progresiva que ocasiona, para el tipo Duchenne, la muerte por falla cardiaca y/o respiratoria durante la segunda década de la vida. Para el tipo Becker las alteraciones musculares son menos severas y los pacientes generalmente sobreviven hasta la edad adulta. El gen DMD, responsable de la enfermedad, se localiza en el brazo corto del cromosoma X y se hereda en forma recesiva ligada al cromosoma X. La mutación más frecuentemente asociada a esta enfermedad es la eliminación genética de diversas partes del gen DMD.La identificación del estado portador sólo se pude realizar mediante estudios moleculares, debido a la ausencia de manifestaciones clínicas en las posibles portadoras.En el presente trabajo se estudió la distribución de eliminaciones genéticas en el gen DMD de pacientes mexicanos con DMD/BMD y se identificaron portadoras para esta enfermedad en familias mexicanas con antecedentes de la miopatía y que no se habían estudiado previamente.Método: Se obtuvo DNA y RNA de linfocitos de sangre periférica de pacientes con DMD/BMD y mujeres en riesgo, pertenecientes a familias mexicanas con antecedentes de esta enfermedad. La concentración e integridad de los ácidos nucleicos se determinó por espectrometría y electroforesis en geles de agarosa. Las eliminaciones genéticas se identificaron por ensayos de amplificación múltiple, analizándose los 2 puntos calientes de mutación y la región promotora del gen.El diagnóstico molecular de portadoras se realizó mediante estudios de ligamiento genético empleando 5 marcadores microsatélites localizados en el gen DMD. En las familias en donde se identificó la eliminación genética el diagnóstico de portadoras se hizo mediante amplificación en cadena de la polimerasa acoplada a la síntesis de cDNA (RT-PCR).Resultados: Se identificaron eliminaciones genéticas en 8/23 pacientes.  En cuatro afectados se pudo definir la extensión de la eliminación, en uno de ellos, ésta también afectó a los genes cercanos GK y DAX-1. Se identificó un empalme alternativo en un paciente, lo que explicaría el fenotipo leve que presenta. Con estudios de ligamiento genético y RT-PCR, 6/10 mujeres fueron portadoras. Discusión o Conclusión: El porcentaje de eliminaciones genéticas en los pacientes estudiados fue menor al reportado en otras poblaciones. Un estudio con un mayor número de individuos permitirá saber sí esta baja frecuencia es característica de nuestra población. El uso de estudios de ligamiento genético y de RT-PCR aumenta la posibilidad de definir el estado portador en mujeres pertenecientes a familias con DMD/BMD y así poder ofrecerles un adecuado consejo genético. Este es el primer trabajo realizado en México, donde se usó el RT-PCR como herramienta diagnóstica en esta distrofia, se identificó por primera vez, a nivel molecular, un paciente con Síndrome de genes continuos y se demostró un empalme alternativo en un paciente con esta miopatía para explicar su fenotipo.

[Hyperemesis gravidarum: management and nutritional implications; case report and review of literature]

INTRODUCTION

Hyperemesis gravidarum is a state of severe nausea and vomiting during pregnancy, leading to dehydration, electrolyte and acid-base disorders, malnutrition and weight loss (> 5%). The prevalence of hyperemesis gravidarum is 0.3-2.3% of all pregnancies.

OBJECTIVE

To demonstrate the effectiveness of nutritional support in a case of a complicated hyperemesis gravidarum. A case of a 25 years old woman with hyperemesis gravidarum, who had weight loss of 17.7%, dehydration, electrolyte disorders and arrhythmias, managed with enteral and parenteral nutrition at home until week 26 of gestation reaching to cover 70% of her caloric requirements orally, getting a healthy product and a stable nutritionally mother in late pregnancy.

CONCLUSIONS

The multidisciplinary management and specialized nutritional management in such cases it is compulsory to carry the patient and the product at the end of pregnancy in optimal conditions.

The neurofibromin 1 type I isoform predominance characterises female population affected by sporadic breast cancer: preliminary data

AIMS

Neurofibromin 1 (NF1) as a tumour suppressor gene can give rise to several transcripts by an alternative splicing event, generated at least for CELF cofactors. At present, the NF1 isoforms and CELF splicing transcripts in sporadic breast cancer are unknown. The aim of the authors was to detect NF1 gene expression, the NF1 isoform ratio and the CELF transcripts present in sporadic breast cancer.

METHODS

Neurofibromin and RAS expression were analysed on tissue microarrays containing sporadic breast cancer (n=22), benign lesions (n=18, including six fibroadenomas, six fibrocystic changes and six ductal hyperplasias) and normal breast tissue (n=6) by immunohistochemistry assay. NF1 and CELF 3-6 RNA expression was performed by end point reverse transcription-PCR in the breast samples.

RESULTS

NF1 and RAS expression in breast tissues showed no differential expression by immunohistochemistry results. Interestingly, the authors observed a shift transition in the isoform transcripts, from type II in normal breast tissue to type I isoform in breast carcinomas. CELF cofactor expression failed to be related with the shift transition of NF1 in breast tissues.

CONCLUSIONS

These data suggest that there is a tendency for an NF1 expression shift transition from type II to type I isoform, which could comprise a significant event in the development and progression of sporadic breast cancer. This shift transition may not be related with CELF cofactors.

Biomarker analysis by tissue microarray technology of Bik, Bcl-2, Bax, ER-α, ER-β, Her2/neu, PCNA, P53, pRB proteins and apoptotic index (by TUNEL) in breast cancer Mexican biopsies

Abstract #4043

Background: 
 The development and progression of epithelial cancers are the results of changes in many genetic networks. Through massive analysis techniques various prognostic factors have been studied to determine proteins implicated in cancer. A new technology used is tissue microarray (TMAs), which allows the assessment of several patients at different stages in a single slide.
 Methods:
 TMA blocks with up to 128 cylinders were made by using 1.5-mm diameter tissue cores from each paraffin block. In a series of 70 formalin-fixed carcinomas, we analyzed the immuno-expression of Bik, Bcl-2, Bax, ER-α, ER-β, Her2, PCNA, P53 and RB proteins. For apoptosis detection the TUNEL technique was used. Expression profiles for these tumors were generated with an unsupervised clustering and a T Test analysis.
 Results:
 We developed TMAs with samples from Mexican women with breast cancer at different stages (type I, II and III) and compared these with those of non affected breast tissue of the same women's samples. Through a hierarchical cluster we found three subgroups of tumors according to protein expression behavior. The apoptotic process was found in low grade 4.28%; moderate grade 90% and high grade 5.71% of samples. Statistical analysis revealed that Bax gene (p=0.000) expression was significantly increased in samples stage I and underexpressed in samples stage IIIA. The Bcl-2 gene was under-expressed in the majority of samples of the stage II. Even when the Bik gene was detected the protein level was over-expressed in 44.29% of the cases with noa significant correlation with apoptosis (TUNEL) (p=0.006). The samples where there were more alterations of the studied proteins were understood in the stages IIA (T2N0M0) and IIB (T2N1M0).
 
 Conclusions:
 The analysis of specimens of several patients in different stages of the disease turns out to be useful to establish a better diagnosis and prognosis. Differential regulation of these genes, especially Bik and Bax, may contribute to the biological nature of a clinically more aggressive and highly proliferative breast cancers.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4043.

pRB detection as a common event in human retinoblastomas: an immunohistochemical study

Approximately 30% of the cases of retinoblastoma (RB), the childhood eye cancer, are inherited and are manifested by unilateral or bilateral tumor. In sporadic tumors, accounting for 70% of cases, only one eye is affected. RB has three histological features: undifferentiated anaplastic cells, retinoblast pattern, and differentiated pattern characterized by Flexner Wintersteiner rosettes (FWR). Currently, results concerning phosphoprotein RB (pRB) expression in RB tumors are contradictory. In this study we detected pRB immunohistochemically in 10 tumors from bilateral or unilateral RBs, which did not show gross chromosomal alterations in cytogenetic studies. Interestingly, pRB was undetectable in only one tumor where we found distinct histological features. Our results suggest that pRB immunopositivity may be common in these tumors. However, it does not rule out the possibility that pRB is functionally inactive in some cases. This may be due to the protein being present in phosphorylated form or being altered by point mutations not affecting its expression. Another possibility is that mechanisms other than RB1 gene changes may lead to retinoblastoma because not all cases of retinoblastoma show gene alterations. Together these findings may be useful in understanding the molecular mechanisms associated with this type of pediatric tumor.

Molecular study of VWF gene from Mexican Mestizo patients with von Willebrand disease, and the finding of three new mutations

To investigate the origin of von Willebrand disease in Mexican Mestizo population, we analyzed exons 18, 19, 20, 28, 45, and 52 of the VWF gene from 34 Mexican Mestizo index cases, 28 of them affected but not related, using DNA amplification by polymerase chain reaction and direct sequencing. We found three novel mutations: E1447Q in one patient with type 1; P2781S in one patient with type 2M; and P812L in another type 1/2N patient. These mutations were not found in 100 normal alleles. Moreover, we found other mutations previously reported in the literature; one of them (G1609R) was the most frequent (6/28) in patients with VWD type 2A. This is the first molecular study in a Mexican group that has a particular mixture of Indigenous, Caucasian, and African genes.

In vitro leukemic cell differentiation and WT1 gene expression

Cell differentiation and four WT1 isoforms were assessed in CD34(+) cells from patients with acute myelogenous leukemia in presence or absence of recombinant human GM-CSF and G-CSF, on days 0, 10 and 20 of culture. We found that WT1 isoforms expression was consistently higher in AML-derived CD34+ cell-enriched cell fractions, as compared to their normal counterparts, and interestingly, in both cases, cells had differentiation towards the myeloid lineage with WT1 expression different patterns. This data suggest that WT1 expression seems to be modulated by the presence of cytokines, especially on day 20 of culture.

A molecular analysis by gene expression profiling reveals Bik/NBK overexpression in sporadic breast tumor samples of Mexican females

Background

Breast cancer is one of the most frequent causes of death in Mexican women over 35 years of age. At molecular level, changes in many genetic networks have been reported as associated with this neoplasia. To analyze these changes, we determined gene expression profiles of tumors from Mexican women with breast cancer at different stages and compared these with those of normal breast tissue samples.

Methods

³²P-radiolabeled cDNA was synthesized by reverse transcription of mRNA from fresh sporadic breast tumor biopsies, as well as normal breast tissue. cDNA probes were hybridized to microarrays and expression levels registered using a phosphorimager. Expression levels of some genes were validated by real time RT-PCR and immunohistochemical assays.

Results

We identified two subgroups of tumors according to their expression profiles, probably related with cancer progression. Ten genes, unexpressed in normal tissue, were turned on in some tumors. We found consistent high expression of Bik gene in 14/15 tumors with predominant cytoplasmic distribution.

Conclusion

Recently, the product of the Bik gene has been associated with tumoral reversion in different neoplasic cell lines, and was proposed as therapy to induce apoptosis in cancers, including breast tumors. Even though a relationship among genes, for example those from a particular pathway, can be observed through microarrays, this relationship might not be sufficient to assign a definitive role to Bik in development and progression of the neoplasia. The findings herein reported deserve further investigation.

Identification of chromosomal changes with comparative genomic hybridization in sporadic breast cancer in Mexican women

Breast cancer is the second leading cause of death in women older than 35 years in Mexico. In this study, we used comparative genomic hybridization (CGH) to analyze sporadic breast cancers at stages II and III from untreated patients. We obtained 4.1 chromosomal alterations per sample, less than in previous reports. We identified a small region in Xq27 with high-level amplification in 3 of 16 samples. This amplification has been reported only in pancreatic and gastric cancer cell lines and in testis tumors; in addition, this amplification had been reported in one primary breast cancer, but in a more extended region that we identified. We also identified a loss in 2p13, not previously reported in this neoplasia. The most frequent alterations were amplifications in 4q, 5q, 8q, 12p, and 13q and losses in 1p, 8p, 16p, 19q, and Xp. CGH provides data for better understanding of molecular events in this neoplasia.

[Guidelines on hemodialysis-associated viral infections]

The viric infections influence morbi-mortality in Chronic kidney Disease patients in hemodialysis therapy and can affect to the Staff of the Units. The guides considered the most relevant virus at the present moment: C Virus, B Virus and HIV. To prevent horizontal nosocomial transmission is necessary the observance always the universal precautions in the HD units, although sometimes can appeared seroconversions and epidemic bud when exist a break of these. Is analyzed different situations with special focus in units for acute patients. The following steps under the suspicious of the epidemic bud appeared in one of the annexes together with legislation according to this case. Respect to the staff in every one of the virus is shown prevention patterns, serologic markers to perform when an accident with infected blood occur, also is considered when treatment is indicated. The guides considered too the conditions necessary for include these patients on waiting list for kidney transplantation.

Identification of novel mutations in the RB1 gene in Mexican patients with retinoblastoma

Retinoblastoma (RB) is a childhood tumor of the eye with an average incidence of one case in every 15,000-20,000 live births and occurs in sporadic or hereditary form. This cancer results from loss or inactivation of the RB1 gene located at 13q14.1. This gene encodes for a 110 Kd nuclear phosphoprotein (pRB) that plays a major role in cell proliferation control. Different types of mutations in the RB1 gene have been reported, but point mutations are the most common. There are no molecular studies on RB1 gene mutation in Mexican patients. In this study, 19 patients with bilateral or unilateral RB were analyzed. Genetic and cytogenetic studies were carried out. Detection of RB1 gene mutations was done using single-strand conformational polymorphism (SSCP). Five conformational polymorphisms were identified in different exons. In all cases, SSCP sequence showed new non-described mutations that produced a frameshift on the open reading frame. The identification of mutations in the RB1 gene contributes to basic knowledge of this neoplasia and permits the possibility to offer adequate genetic counseling to relatives at risk.

(AC)n dinucleotide repeat polymorphism in 5' beta-globin gene in native and Mestizo Mexican populations

Repeated sequences are dispersed along the human genome. These sequences are useful as markers in diagnosis of inherited diseases, in forensic medicine, and in tracking the origin and evolution of human populations. The (AC)n repeated element is the most frequent in the human genome. In this paper, the (AC)n repeated element located in the 5' flanking region of the beta-globin gene was studied by single-strand conformation polymorphism (SSCP). Four ethnic Mexican groups (Mixteca, Nahua, Otomí, Purépecha) and a Mestizo population were analyzed. We observed three alleles, A [(AC)16, B [(AC)14], and C [(AC)18], with a frequency of between 68.2% and 86.9%, 13.1% and 18.2%, and 6.7% and 13.7%, respectively. Allele C was present only in Purépecha and Mestizo groups. The absence of this allele in the other ethnic groups studied suggests that there is low genetic admixture of Purépecha and that this is a relatively isolated population. However, it could be that the C allele occurs in low frequencies in the other groups as a result of small sample sizes. The (AC)n repeat polymorphism in the beta-globin gene has not been previously studied in Amerindian populations.

Pattern of deletions of the dystrophin gene in Mexican Duchenne/Becker muscular dystrophy patients: the use of new designed primers for the analysis of the major deletion "hot spot" region

We have analyzed 59 unrelated Mexican Duchenne/Becker muscular dystrophy patients (DMD/BMD) using PCR analysis of the 2 prone deletion regions in the DMD gene. Thirty one (52%) of the patients had a deletion of one or several of the exons. Most of the alterations (87%) were clustered in exons 44-52, this being the highest percentage reported until now. In order to improve the molecular diagnosis in the Mexican population, we designed a new multiplex assay to PCR amplify exons 44-52. This assay allowed for the identification of a greater number of deletions in this region compared with the 9 and 5-plex assays previously described and to determine most of the deletion end boundaries. This is a reliable alternative for the initial screening of the DMD patients in the Mexican population.