O Papel da 1,25(OH)2D3 (VD3) ou calcitriol, o metabolito ativo da Vitamina D, em câncer de mama tem sido extremamente explorado. Os efeitos antiproliferativos, prodiferenciativos e antiinflamatórios da VD3 são bem documentados na literatura. Análises de microarray vêm auxiliando a identificação de vários genes responsivos e modulados pela VD3 e seus análogos. A maioria desses genes apresentados na literatura é proveniente de estudos utilizando linhagens celulares de câncer de mama ou modelos animais. Pouco é sabido sobre a ação da VD3 em outros tipos celulares constituintes do microambiente tumoral. Fibroblasto associado ao câncer (FAC), o principal componente do microambiente tumoral, apresenta um papel central no complexo processo de interação entre tumor e estroma e consequentemente em todos os passos envolvidos na tumorigênese. O objetivo do nosso estudo foi identificar genes chaves regulados pela VD3 em fibroblastos associados ao câncer de mama. Para isso, culturas primárias de fibroblastos provenientes de cinco amostras de carcinoma mamário ductal invasivo foram estabelecidas e posteriormente caracterizadas fenotipicamente por um conjunto de marcadores. Após a confirmação da presença de receptor de vitamina D, os fibroblastos de cada amostra foram divididos em três grupos: um grupo controle e grupos de tratamento com 0,5 nM e 100 nM de VD3 durante 24 horas. A determinação do perfil de expressão gênica foi realizado utilizando tecnologia de oligo microarray com o GeneChip Human Genome U133 Plus 2.0 (Affymetrix). Foram obtidos 274 genes diferentemente expressos entre os grupos controle e tratamento com 0,5 nM de VD3, muitos deles envolvidos em processos como apoptose e migração celular. Os 161 genes diferentemente expressos obtidos a partir da comparação entre grupos controle e tratamento com 100 nM de VD3 apresentaram-se funcionalmente envolvidos em diversos processos biológicos, sendo que os mais significativos processos regulados pela VD3 em fibroblastos associados ao câncer de mama foram respostas inflamatória e imune, sugerindo que a ação antiinflamatória da VD3, anteriormente relatada em estudos utilizando células epiteliais de câncer de mama, pode também ser aplicada a fibroblastos associados ao câncer de mama / The role of 1,25(OH)2D3 (calcitriol), the active metabolite of Vitamin D, in breast cancer has been extremely explored. Antiproliferative, prodifferentiating and anti-inflammatory effects of calcitriol have been reported in breast cancer. Expression profile by microarray analysis has identified many responsive genes modulated by calcitriol and analogs. The majority of them defined to date are based on studies using breast cancer cell lines or mouse models. Little is known about the action of calcitriol in the others cell types present into the tumor microenvironment. Cancerassociated fibroblasts (CAFs), the principal cell component of the tumor microenvironment, play a central role in the complex process of tumour stroma interaction and consequently in all breast cancer tumorigenesis steps. The aim of our study was to identify key genes that are regulated by calcitriol in breast cancer associated fibroblasts. Primary fibroblasts cell cultures from five breast cancer samples were established and then phenotyping characterized by a set of markers. The occurrence of vitamin D receptor was confirmed in all samples and fibroblasts were divided in three groups: one control group and two treatment groups, 0.5 nM and 100 nM of calcitriol during 24 hours. The determination of gene expression profile was performed by oligo microarray technology using the GeneChip Human Genome U133 Plus 2.0 (Affymetrix). Control and 0.5 nM calcitriol analysis resulted in 274 differentially expressed genes, many of then involved in biological processes as apoptosis and cell migration. The 161 differentially expressed genes obtained from comparison between groups control and 100 nM calcitriol treatment were functionally involved in several biological processes. The most significantive processes regulated by VD3 in breast CAFs were the inflammatory and immune responses, suggesting that the anti-inflammatory action of calcitriol, yet reported in several studies using epithelial breast cancer cells, may also been applied to breast cancer associated fibroblasts

La greffe cardiaque est le traitement ultime de l’insuffisance cardiaque. Le rejet aigu pose plusieurs problématiques, en particulier sa survenue imprévisible même sous traitement immunosuppresseur, et un diagnostic histologique qui nécessite des biopsies endomyocardiques (BEM) invasives répétées, et qui souffre de nombreuses limites. Le besoin de critères diagnostiques et prédictifs, idéalement non invasifs, nous a conduits à étudier le rejet aigu de greffe cardiaque sur le plan moléculaire. Nous avons caractérisé les profils d’expression génique (PEG) myocardiques et sanguins lors de différentes phases du rejet cellulaire (RC) et du rejet médié par les anticorps (RMA), par analyse sans a priori des transcriptomes sur puce à ADN. Par une première étude des PEG myocardiques menée sur une collection historique de BEM, nous avons montré la modification des PEG tissulaires lors du RC. Pour le même grade histologique, deux profils de RC aux degrés d’activation immunitaire différents ont été identifiés. De plus, les PEG myocardiques étaient modifiés dès un mois avant la survenue d’un RC, quand l’analyse histologique ne montrait encore aucune anomalie. Par une seconde étude conduite sur une collection prospective de BEM et échantillons sanguins, nous avons confirmé les résultats de la première étude, et de plus montré l’existence de modulations des PEG également dans le sang périphérique, aussi bien pendant un épisode de RC qu’un mois avant. Enfin pour la première fois la modulation tissulaire et périphérique des PEG a été montrée dans le RMA en transplantation cardiaque. L’existence de voies modulées dans les deux types de rejet devrait conduire à la recherche de biomarqueurs. / Heart transplantation is the last treatment in case of terminal heart failure. Acute rejection after heart transplantation raises several issues due to its occurrence despite immunosuppressive therapies and the requirement of invasive and repeated endomyocardial biopsies (EMB) that have several histological grading limitations. The need of non-invasive diagnostic and predictive criteria led us to study the acute rejection of cardiac allograft using a molecular approach. We characterized myocardial and peripheral blood gene expression profiles (GEP) during acute cellular rejection (CR) and antibody-mediated rejection (AMR) by mean of microarray analyses. By a retrospective study conducted on a historical EMB collection, we first showed a strong immunologic modulation during CR. For the same CR histological grading, two transcriptional profiles were identified according to the inflammation level. Moreover, myocardial GEP modifications were observed one month before the occurrence of CR, while histological characteristics showed no abnormality. A second study conducted on a prospective collection of both EMB and peripheral blood samples confirmed the results obtained on EMB and showed peripheral blood GEP modulations during both CR and even one month earlier. Finally, we have also shown for the first time in heart transplantation, myocardial and peripheral GEP modulations in AMR. Identification of modulated pathways in both types of rejection should allow for the determination of rejection biomarkers.

Colorectal cancer is one of the most common cancer types worldwide. Both genetic and epigenetic alterations play a critical role in its initiation and progression. One of the genes frequently epigenetically silenced or lost in many types of human cancer is tumor suppressor gene Hypermethylated in Cancer 1 (HIC1). It encodes for transcriptional repressor regulating its target genes directly or indirectly. Twelve genes whose expression is repressed by HIC1 have been identified to date. These genes encode for transcription factors, cell cycle and apoptosis regulators or proteins involved in angiogenesis as well as cell migration and invasiveness. Employing mouse embryonic fibroblasts upon Hic1-conditional knockout we have revealed six novel genes potentially repressed by Hic1 including Toll-like receptor 2 (Tlr2). Here we show that Tlr2 is one of the Hic1 target genes and that Hic1 inactivation in the intestine leads to increased Tlr2 production. Moreover, enhanced inflammatory response upon chemical-induced colitis as well as increased tumor formation in ApcMin mice was observed in Hic1-deficient mice. Expression profiling in human fibroblast upon HIC1 knockdown revealed increased expression of another potential target gene, transcription factor E2F7. Our study describes a new relationship between HIC1 and...

Le CD81 est une molécule de surface appartenant à la superfamille des tetraspanines. Son rôle pronostique a été précédemment étudié dans les pathologies lymphoïdes, dont le myélome multiple où son expression est associée à un pronostic péjoratif. A ce jour, ce marqueur n'a pas été étudié dans les leucémies aiguës myéloïdes (LAM). Nous avons étudié l'expression membranaire du CD81 sur les blastes de LAM au diagnostic, son association aux autres caractéristiques des LAM et sa potentielle influence sur la survie des patients sur une cohorte de 134 patients traités par chimiothérapie intensive.Le CD81 a été retrouvé chez 92 patients sur 134 (69%). Les patients exprimant ce marqueur avaient une leucocytose initiale plus élevée (p=0.02) et présentaient une cytogénétique intermédiaire ou défavorable (p<0.001). L'expression du CD81 avait un impact négatif sur la survie des patients (survie sans évènements (EFS), survie globale (OS), survie sans rechute (RFS)) en analyse uni- (p<0.001) et multivariées (p=0.003, 0.002 and <0.001 respectivement).De plus, le CD81 avait un impact négatif sur l'OS des patients avec une mutation de NPM1 (p=0.01) et chez les patients du groupe cytogénétique favorable (p=0.002) selon la classification ELN.Les anomalies du cycle cellulaire étant associées à la chimiorésistance, la croissance tumorale et l'agressivité de la pathologie, nous avons étudié l'expression du Ki67 sur les blastes de LAM au diagnostic. Ainsi, 10 prélèvements médullaires de patients avec une faible expression du CD81 par les blastes (moins de 20% de positivité) et 10 prélèvements avec une forte expression du marqueur ont été étudiés. Nous avons pu démontrer une expression significativement inférieure du Ki67 sur les blastes CD81 positifs par rapport aux blastes CD81 négatifs (p<0.001), suggérant ainsi un rôle potentiel du CD81 dans le contrôle du cycle cellulaire. De plus, nous nous sommes intéressés au rôle du CD81 dans la chimiorésistance et sur les différentes voies de signalisation cellulaire en étudiant le profil d'expression génique.En conclusion, le CD81 semble être un nouveau marqueur pronostique des LAM ainsi qu'une cible potentielle de traitement de ces pathologies. / CD81 is a cell surface protein which belongs to the tetraspanin family. While in multiple myeloma its expression on plasma cells is associated with worse prognosis, this has not yet been explored in acute myeloid leukemia (AML). We measured membrane expression of CD81 on AML cells at diagnosis, evaluated its association with AML characteristics and its influence on patient outcome after intensive chemotherapy in a cohort of 134 patients. CD81 was detected in 92/134 (69%) patients. Patients with AML expressing CD81 had elevated leukocyte count (p=0.02) and were more likely classified as intermediate or adverse-risk by cytogenetics (p<0.001). CD81 expression had a negative impact on survival (event-free [EFS], overall [OS] and relapse-free survival [RFS]) in univariate (p<0.001) and in multivariate analyses (p=0.003, 0.002 and <0.001, respectively). CD81 has a negative impact on OS in patients with NPM1 mutation (p=0.01) and in favorable risk patients by European Leukemia Net (ELN) classification (p=0.002).Since aberrations in cell cycle signaling can cause drug resistance, tumor growth and aggressiveness we measured Ki67 on primary blast cells from AML patients. We considered 10 bone marrow samples from AML patients with either weak CD81 expression (less than 20% of blast cells) or 10 bone marrow samples with strong CD81 expression on blasts. We found a significant lower ki67 expression on blast cells from CD81 positive patients compared with those from CD81 negative patients (p<0.001), indicating a potential role of CD81 in cell cycle control. Furthermore, we investigated the role of CD81 in chemotherapy resistance and investigated potentially implicated signaling pathways by gene expression profiling.In conclusion, the cell surface marker CD81 may be a new prognostic marker for diagnostic risk classification and a new potential therapeutic target for drug development in AML.

Common bean is a major dietary component in several countries, but its productivity is negatively affected by abiotic stresses. Dissecting candidate genes involved in abiotic stress tolerance is a paramount step toward the improvement of common bean performance under such constraints. Thereby, this thesis presents a systematic analysis of the DEHYDRATION RESPONSIVE ELEMENT-BINDING (DREB) gene subfamily, which encompasses genes that regulate several processes during stress responses, but with limited information for common bean. First, a series of in silico analyses with sequences retrieved from the P. vulgaris genome on Phytozome supported the categorization of 54 putative PvDREB genes distributed within six phylogenetic subgroups (A-1 to A-6), along the 11 chromosomes. Second, we cloned four novel PvDREB genes and determined their inducibility-factors, including the dehydration-, salinity- and cold-inducible genes PvDREB1F and PvDREB5A, and the dehydration- and cold-inducible genes PvDREB2A and PvDREB6B. Afterwards, nucleotide polymorphisms were searched through Sanger sequencing along those genes, revealing a high number of single nucleotide polymorphisms within PvDREB6B by the comparison of Mesoamerican and Andean genotypes. The nomenclature of PvDREB6B is discussed in details. Furthermore, we used the BARCBean6K_3 SNP platform to identify and genotype the closest SNP to each one of the 54 PvDREB genes. We selected PvDREB6B for a broader study encompassing a collection of wild common bean accessions of Mesoamerican origin. The population structure of the wild beans was accessed using sequence polymorphisms of PvDREB6B. The genetic clusters were partially associated with variation in latitude, altitude, precipitation and temperature throughout the areas such beans are distributed. With an emphasis on drought stress, an adapted tube-screening method in greenhouse conditions enabled the phenotyping of several drought-related traits in the wild collection. Interestingly, our data revealed a correlation between root depth, plant height and biomass and the environmental data of the location of the accessions. Correlation was also observed between the population structure determined through PvDREB6B and the environmental data. An association study combining data from the SNP array and DREB polymorphisms enabled the detection of SNP associated with drought-related traits through a compressed mixed linear model (CMLM) analysis. This thesis highlighted important features of DREB genes in common bean, revealing candidates for further strategies aimed at improvement of abiotic stress tolerance, with emphasis on drought tolerance / O feijoeiro é um componente essencial na dieta em diversos países, no entanto, sua produção é afetada negativamente por estresses abióticos. O estudo de genes candidatos envolvidos na adaptação aos estresses é uma etapa fundamental para o melhoramento da performance do feijoeiro sob tais estresses. Desse modo, esta tese apresenta uma análise sistemática da subfamília de genes DEHYDRATION RESPONSIVE ELEMENT-BINDING (DREB), que reúne genes envolvidos em diversos processos em resposta a estresses, mas pouco estudados no feijoeiro. Primeiramente, uma série de análises in silico com sequências de feijoeiro obtidas da plataforma Phytozome possibilitaram a categorização de 54 genes PvDREB putativos, distribuídos em seis subgrupos (A-1 até A-6) nos 11 cromossomos da espécie. Posteriormente, quatro novos genes PvDREB foram clonados e seus padrões de inducibilidade foram determinados. PvDREB1F e PvDREB5A foram induzidos por desidratação, baixa temperatura e salinidade, enquanto PvDREB2A e PvDREB6B foram predominantemente induzidos por desidratação e baixa temperatura. Polimorfismos de nucleotídeos foram buscados através de sequenciamento por método derivado de Sanger, revelando elevado número de SNP no gene PvDREB6B. A nomenclatura desse gene foi discutida detalhadamente ao longo da tese. A plataforma de marcadores SNP BARCBean6K_3 foi acessada para identificar o SNP mais próximo de cada um dos 54 PvDREB. O gene PvDREB6B foi selecionado para um estudo mais amplo, envolvendo uma coleção de acessos selvagens de origem Mesoamericana. A estrutura populacional destes genótipos foi analisada a partir de polimorfismos na sequência de PvDREB6B. Os grupos genéticos apresentaram associação parcial com variação da latitude, altitude, precipitação e temperatura das áreas em que os acessos naturalmente ocorrem. Com ênfase no estudo do déficit hídrico, uma plataforma de fenotipagem destes acessos em casa de vegetação, utilizando um sistema de tubos plásticos, foi elaborada para a análise de diversos parâmetros relacionados ao estresse por déficit hídrico. Os dados revelaram correlação entre profundidade de raízes, altura das plantas e a biomassa e as variáveis ambientais de cada local. A correlação também foi detectada entre a estrutura populacional estudada por PvDREB6B e os dados ambientais. Finalmente, um estudo de associação genética foi realizado entre os SNP da plataforma e ligados a DREB e os parâmetros fenotípicos, permitindo a identificação de marcadores SNP associados a caracteres específicos, usando um modelo linear misto (CMLM). Esta tese apresentou importantes aspectos sobre os genes DREB em feijoeiro, revelando candidatos para seu uso em estratégias de melhoramento para tolerância a estresses abióticos, com ênfase em déficit hídrico

O Papel da 1,25(OH)2D3 (VD3) ou calcitriol, o metabolito ativo da Vitamina D, em câncer de mama tem sido extremamente explorado. Os efeitos antiproliferativos, prodiferenciativos e antiinflamatórios da VD3 são bem documentados na literatura. Análises de microarray vêm auxiliando a identificação de vários genes responsivos e modulados pela VD3 e seus análogos. A maioria desses genes apresentados na literatura é proveniente de estudos utilizando linhagens celulares de câncer de mama ou modelos animais. Pouco é sabido sobre a ação da VD3 em outros tipos celulares constituintes do microambiente tumoral. Fibroblasto associado ao câncer (FAC), o principal componente do microambiente tumoral, apresenta um papel central no complexo processo de interação entre tumor e estroma e consequentemente em todos os passos envolvidos na tumorigênese. O objetivo do nosso estudo foi identificar genes chaves regulados pela VD3 em fibroblastos associados ao câncer de mama. Para isso, culturas primárias de fibroblastos provenientes de cinco amostras de carcinoma mamário ductal invasivo foram estabelecidas e posteriormente caracterizadas fenotipicamente por um conjunto de marcadores. Após a confirmação da presença de receptor de vitamina D, os fibroblastos de cada amostra foram divididos em três grupos: um grupo controle e grupos de tratamento com 0,5 nM e 100 nM de VD3 durante 24 horas. A determinação do perfil de expressão gênica foi realizado utilizando tecnologia de oligo microarray com o GeneChip Human Genome U133 Plus 2.0 (Affymetrix). Foram obtidos 274 genes diferentemente expressos entre os grupos controle e tratamento com 0,5 nM de VD3, muitos deles envolvidos em processos como apoptose e migração celular. Os 161 genes diferentemente expressos obtidos a partir da comparação entre grupos controle e tratamento com 100 nM de VD3 apresentaram-se funcionalmente envolvidos em diversos processos biológicos, sendo que os mais significativos processos regulados pela VD3 em fibroblastos associados ao câncer de mama foram respostas inflamatória e imune, sugerindo que a ação antiinflamatória da VD3, anteriormente relatada em estudos utilizando células epiteliais de câncer de mama, pode também ser aplicada a fibroblastos associados ao câncer de mama / The role of 1,25(OH)2D3 (calcitriol), the active metabolite of Vitamin D, in breast cancer has been extremely explored. Antiproliferative, prodifferentiating and anti-inflammatory effects of calcitriol have been reported in breast cancer. Expression profile by microarray analysis has identified many responsive genes modulated by calcitriol and analogs. The majority of them defined to date are based on studies using breast cancer cell lines or mouse models. Little is known about the action of calcitriol in the others cell types present into the tumor microenvironment. Cancerassociated fibroblasts (CAFs), the principal cell component of the tumor microenvironment, play a central role in the complex process of tumour stroma interaction and consequently in all breast cancer tumorigenesis steps. The aim of our study was to identify key genes that are regulated by calcitriol in breast cancer associated fibroblasts. Primary fibroblasts cell cultures from five breast cancer samples were established and then phenotyping characterized by a set of markers. The occurrence of vitamin D receptor was confirmed in all samples and fibroblasts were divided in three groups: one control group and two treatment groups, 0.5 nM and 100 nM of calcitriol during 24 hours. The determination of gene expression profile was performed by oligo microarray technology using the GeneChip Human Genome U133 Plus 2.0 (Affymetrix). Control and 0.5 nM calcitriol analysis resulted in 274 differentially expressed genes, many of then involved in biological processes as apoptosis and cell migration. The 161 differentially expressed genes obtained from comparison between groups control and 100 nM calcitriol treatment were functionally involved in several biological processes. The most significantive processes regulated by VD3 in breast CAFs were the inflammatory and immune responses, suggesting that the anti-inflammatory action of calcitriol, yet reported in several studies using epithelial breast cancer cells, may also been applied to breast cancer associated fibroblasts

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis. To improve the prognosis, novel molecular markers and targets for earlier diagnosis and adjuvant and/or neoadjuvant treatment are needed. Recent advances in human genome research and high-throughput molecular technologies make it possible to cope with the molecular complexity of malignant tumors. With DNA array technology, mRNA expression levels of thousand of genes can be measured simultaneously in a single assay. As several studies using microarrays in PDAC have already been published, this review attempts to compare the published data and therefore to validate the results. In addition, the applied techniques are discussed in the context of pancreatic malignancies. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Systems biology approaches have allowed for comprehensive understanding of complicated biological processes. Here, we’ve developed a global phenotypic profiling method by improving upon transposon mutagenesis methods for identifying genes required for bacterial growth in various conditions. By using the massively parallel power of Illumina sequencing, we precisely redefined the genes required for the growth of Mycobacterium Tuberculosis (Mtb) in vitro. This adapted technique provided more informative data with both increased dynamic range and resolution. As a result, we quantitatively assessed the fitness of individual mutants, as well as identified sub-genic essentiality. Mtb is well adapted to its nutrient-limiting intracellular niche. One important and novel adaptation is its ability to consume cholesterol for both energy and carbon. A combination of this genome-wide phenotypic analysis and global metabolite profiling was used to define the dedicated cholesterol catabolic pathway, as well as important transcriptional and metabolic adaptations required for the consumption of this carbon source. We identified the methylcitrate cycle (MCC) and an unexpected gluconeogenic route as essential pathways. Furthermore, we found that the cholesterol-dependent transcriptional induction of these metabolic enzymes was also essential for growth on this substrate, a function mediated by the Rv1129c regulatory protein. Using a combination of genetic and chemical methods to inhibit these pathways, we show that cholesterol represents a significant source of carbon during intracellular growth in macrophages. Finally, we have begun to define the mechanism by which lipids, such as cholesterol, are imported into the cell by investigating the assembly of the ABC-like lipid transporter, Mce1. The subunits of this system are localized to the cell wall and data is provided to support a novel mechanism for Mce-dependent import of lipids, such as cholesterol. In sum, this global analysis of host cholesterol utilization during infection provides insight into each step of this complicated process; import into the bacterial cell, the degradation of the molecule into primary metabolites, and the transformation of these metabolites into carbon and energy.

No description available.

It is now a matter of routine for the forensic scientist to obtain the genetic profile of an individual from DNA recovered from a biological stain deposited at a crime scene. Potential contributors of the stain must either be known to investigators (i.e. a developed suspect) or the questioned profile must be searched against a database of DNA profiles such as those maintained in the CODIS National DNA database. However, in those instances where there is no developed suspect and no match is obtained after interrogation of appropriate DNA databases, the DNA profile per se presently provides no meaningful information to investigators, with the notable exception of gender determination. In these situations it would be advantageous to the investigation, if additional probative information could be obtained from the biological stain. A useful biometric that could provide important probative information, and one that may be amenable to molecular genetic analysis, is the biological age of an individual. The ability to provide investigators with information as to whether a DNA donor is a newborn, infant, toddler, child, adolescent, adult, middle-aged or elderly individual could be useful in certain cases, particularly those involving young children such as kidnappings or in providing additional intelligence during terrorist investigations. Currently no validated molecular assays exist for age determination. Biological human ageing can be defined by two distinct processes, degenerative and developmental ageing. The degenerative process of ageing is based on theories which identify an increase or decrease in physiological conditions with increasing age. In contrast, the developmental process of ageing is based on the theory that as individuals increase in chronological age, there will be subtle corresponding molecular based biological changes, each requiring genes to be expressed or silenced, indicative of that particular stage of life. We investigated the degenerative process of chromosomal telomere shortening, as well as the developmental process of gene expression profiling analysis, in an attempt to identify biomarkers of biological age in a self-renewing tissue such as blood. While telomere length analysis was an ineffective method for age determination; gene expression analysis revealed three gene transcripts expressed in an age-dependent physiological manner. These species namely- COL1A2, HBE1 and IGFBP3, were found to be expressed at elevated levels in younger individuals, newborns, or post-pubertal individuals, respectively. The biological process of hemoglobin switching was also investigated for the possibility of determining human age. While experimenting with the potential of using the gamma-hemoglobin chains, as newborn specific gene candidates, we serendipitously discovered four novel truncated transcripts, which we have termed HBG1n1, HBG1n2, HBG2n2 and HBG2n3; whose expression was restricted to whole-blood newborn samples and specific fetal tissues. The molecular origin of these transcripts appears to be at the RNA level, being produced by specific rearrangement events occurring in the standard gamma hemoglobin transcripts (HBG1 and HBG2), which yield these new isoforms that are expressed in a highly regulated tissue specific manner.