Hemophagocytic syndrome in a patient with Fanconi anemia and VACTERL association / Síndrome hemofagocítica em paciente com anemia de Fanconi e associação VACTERL

INTRODUCTION: Hemophagocytic syndrome results from hyperactivity of histiocytes and lymphocytes, triggered by infections, mainly viral by cytomegalovirus, Epstein-Barr and herpes. Fanconi anemia (FA) is a rare genetic disease with heterogeneous symptoms common to other diseases such as VACTERL, a disease of unknown etiology in which there are several congenital malformations. The concomitance of Fanconi and VACTERL anemia occurs in 5 to 30% of FA patients. REPORT: A 14-month-old male infant was admitted to investigate fever, hepatosplenomegaly, and granulopenia. The patient was diagnosed with hemophagocytic syndrome due to hyperferritinemia, bone marrow hemophagocytosis, transaminase elevation, decreased fibrinogen, and cytomegalovirus (CMV) infection confirmed by serology and PCR. The test with mitomycin C (MMC) showed chromosomal fragility. The patient was diagnosed with a VACTERL/FA association for having a clinic and a test compatible with both FA and VACTERL. CONCLUSION: The VACTERL/FA association is seldom described, but is present in pediatric medical practice. This study presented the main clinical-laboratory aspects and reviewed the main aspects of the concurrence of this pathology.

INTRODUÇÃO: A síndrome hemofagocítica decorre da hiperatividade de histiócitos e linfócitos e é desencadeada por infeções, principalmente virais por citomegalovírus, Epstein-barr e herpes. A anemia de Fanconi (AF) é uma doença genética rara com sintomas heterogêneos em comum a outras doenças como a associação VACTERL, uma doença de etiologia desconhecida na qual existe diversas mal formações congênitas. A concomitância da anemia de Fanconi e VACTERL é descrita em 5 a 30% dos pacientes AF. RELATO: Lactente de 14 meses, sexo masculino, admitido para investigar um quadro de febre, hepatoesplenomegalia e granulopenia. Os exames laboratoriais mostraram a hiperferritemia, elevação da transaminases, medula óssea com hemofagocitose e, sorologia e PCR positivos para citomegalovírus (CMV). O paciente foi diagnosticado com síndrome hemofagocítica por citomegalovírus. Como havia também hipoplasia do polegar esquerdo, presença de hemivértebra, agenesia renal e teste positivo de fragilidades cromossômicas com mitomicina C (MMC), o paciente foi diagnosticado com associação VACTERL/AF. CONCLUSÃO: O citomegalovírus quando infecta pacientes com problemas de imunidade como AF, apresenta risco de desencadear a síndrome hemofagocítica. A associação VACTERL/AF é pouco descrita, mas presente na prática médica da pediatria. Esse estudo descreveu os principais aspectos clínicos-laboratoriais e revisou os aspectos fundamenais descritos sobre a concomitância dessas patologias.

The epicenter of chromosomal fragility of Fra14A2, the mouse ortholog of human FRA3B common fragile site, is largely attached to the nuclear matrix in lymphocytes but not in other cell types that do not express such a fragility.

Common fragile sites (CFSs) correspond to chromosomal regions susceptible to present breaks, discontinuities or constrictions in metaphase chromosomes from cells subjected to replication stress. They are considered as genomic regions intrinsically difficult to replicate and they are evolutionary conserved at least in mammals. However, the recent discovery that CFSs are cell-type specific indicates that DNA sequence by itself cannot account for CFS instability. Nevertheless, the large gene FHIT that includes FRA3B, the most highly expressed CFS in human lymphocytes, is commonly deleted in a variety of tumors suggesting a tumor suppressor role for its product. Here, we report that the epicenter of fragility of Fra14A2/Fhit, the mouse ortholog of human FRA3B/FHIT that like its human counterpart is the most highly expressed CFS in mouse lymphocytes, is largely attached to the nuclear matrix compartment in naive B lymphocytes but not in primary hepatocytes or cortical neurons that do not express such a CFS. Our results suggest a structural explanation for the difficult-to-replicate nature of such a region and so for its common fragility in lymphocytes, that is independent of the possible tumor suppressor role of the gene harboring such CFS.

Mecanismos de apoptosis en testículos de ratones con rearreglos cromosómaticos robertsonianos / Mechanisms of apoptosis in testes of mice with Robertsonian chromosomal rearrangements

Se han reportado casos de esterilidad masculina en seres humanos portadores de fusiones Robertsonianas. En este trabajo se estudió el deterioro espermatogénico y la participación de las vías apoptóticas en dos modelos animales de ratones machos: híbridos subfértiles (hembras CD1 x machos Milano II) de 5 meses de edad e híbridos infértiles (hembras Graomys griseoflavus x machos Graomys centralis) de 1, 2 y 3 meses de edad, con fusiones Robertsonianas. La presencia de apoptosis se estudió mediante inmunohistoquímica y análisis de Western blots de las moléculas pro-apoptóticas Fas, Fas-L, Bax, citocromo c y caspasa-3, y calbindina D28K como molécula antiapoptótica. La fragmentación del ADN se analizó mediante la técnica de TUNEL. La ultraestructura testicular se visualizó por microscopía electrónica. Los resultados revelaron que la morfología y las asociaciones celulares del epitelio seminífero fueron anormales en los ratones híbridos Robertsonianos, con un mayor deterioro en los híbridos infértiles. Un intenso proceso apoptótico se observó en los túbulos seminíferos del estadio XII en los híbridos subfértiles, principalmente en los espermatocitos en metafase. Estos espermatocitos también mostraron redistribución de Bax y citocromo c. Los ratones híbridos infértiles presentaron mayor mortalidad de células germinales, con arresto de la espermatogénesis en estadios pre-meióticos. La apoptosis de las células germinales se produjo especialmente a nivel de los espermatocitos en paquitene, no llegándose en ningún caso a la espermatogénesis completa. Los espermatocitos de los tres grupos de animales Graomys de 1 mes de edad fueron positivos para todos los marcadores apoptóticos. En los parentales, esta expresión disminuyó a los 2 y 3 meses, mientras que permaneció elevada en los testículos de los híbridos.

Principales factores que producen fragilidad cromosómica transitoria en los pacientes referidos para estudio citogenético / Main factors that produce transitory chromosomic fragility in the patients referred for cytogenetic study

The fragile sites are specific loci that show fractures during karyotyping perform under specific laboratory conditions. Are present in normal individuals and are classified by their population frequency. These sites have been associated with an increase in chromosome fragility, fractures and other chromosomal abnormalities. In recent years, the fragile sites have taken great importance because they represent regions in the genome that are particularly sensitive to replicative stress and are frequently rearrenged in tumor cells. Multiple risk factors endogenous and exogenous have been involved in the increase in chromosome fragility, including microorganisms, drugs, illegal drugs and toxins. The fragile sites have provided insight into understanding of the effects of replicative stress on DNA damage and genomic instability in cancer cells. In this work we aim to summarize the limited information available about the topic, and the clinical significance of fragile sites in vivo in the laboratory.

Localisation of aphidicolin-induced break points in Holstein-Friesian cattle (Bos taurus) using RBG-banding.

Fragile sites (FS) seem to play a role in genome instability and may be involved in karyotype evolution and chromosome aberrations. The majority of common fragile sites are induced by aphidicolin. Aphidicolin was used at two different concentrations (0.15 and 0.30 microM) to study the occurrence of FS in the cattle karyotype. In this paper, a map of aphidicolin induced break points and fragile sites in cattle chromosomes was constructed. The statistical analysis indicated that any band with three or more breaks was significantly damaged (P<0.05). According to this result, 30 of the 72 different break points observed were scored as fragile sites. The Pearson correlation test showed a positive association between chromosome length and the number of fragile sites (r=0.54). On the contrary, 21 FS were identified on negative R bands while 9 FS were located on positive R bands.

Chromosomal defects in 34 male homosexuals, half of them with HIV antibodies.

Most of the research about viral interactions with human chromosomes was done during the sixties and early seventies and very few was performed after the human immunodeficiency virus (HIV) appearance as an epidemic in the eighties. The objective of this work was to estimate if particular chromosomal changes follow the infection of homosexual males by HIV and to determine if the lifestyle, habits, sexual practices, of our sample of male homosexuals predisposes them to chromosomal abnormalities at a higher rate than the background level of cytogenetic damage the general population has. This was a double blinded case-control study, 17 individuals positive for HIV antibodies (HIV+) detected by enzyme-linked immunosorbent assay (ELISA) and confirmed by western blot (WB) were the cases, and 17 individuals negative for HIV antibodies (HIV-) the controls. These men were a very homogeneous population in terms of age, social status, lifestyles, drug abuse, sexual practices and education. Blood was collected between September 1988 and October 1989. Fresh whole blood was cultured in duplicate for 72 hr. Cell harvest followed conventional methods. Once all cell cultures were gathered, the tubes were picked up at random and air dried chromosome preparations were trypsin-giemsa banded (GTG) after overnight incubation at 60 C degrees. The percentage of gaps and breaks these men had was not different from the reported for the general population, nor were there significant difference among both groups (O.R. = 1.8) in items of amount of chromosomal fragility. The distinction among them was at the level of the specific chromosomal sites where the gaps and breaks located, being sites at 2p21 and at 3p21 four times more frequent among HIV+. These probably represent viral modification sites on chromosomes which are known to look like non-staining gaps which are caused by the virus or viral products. This presumption is supported by an earlier report of repeated breaks at 3p21.1, in fact this was the most common lesion site in this study of chromosomal aberrations of male homosexuals and the authors even considered the probability of "a new type of chromosome marker". Furthermore, years later the CKR5 structural gene was mapped to human chromosome 3p21. This gene codes for the chemokine receptor 5 (CKR5) protein which serves as a secondary receptor on CD4+ T lymphocytes for certain strains of HIV-1. It is possible that this gene was being transcribed in HIV+ men and the consequent "staggering" of DNA contributed to the production of gaps and breaks at 3p21.

Fragility in the 14q21q translocation region

Aphidicolin (APC)-induced chromosomal breakage was analyzed for women representing three generations of a single family and carrying a Robertsonian translocation rob(14q21q). Fluorescence in situ hybridization (FISH) analysis confirmed the dicentric constitution of the derived chromosome and indicated the absence of beta-satellite signal at the translocation region. Per-individual analysis of metaphases from APC-treated peripheral blood lymphocyte cultures identified significantly nonrandom chromosomal breakage at the translocation region in all three individuals examined. The APC-inducible fragility at the 14q21q translocation region suggests that this rearrangement was the result of chromosomal mutation at fragile site(s) in the progenitor chromosomes, or that this fragility was the result of the fusion of nonfragile progenitor chromosomes

Nijmegen breakage syndrome: clinical characteristics and mutation analysis in eight unrelated Russian families.

OBJECTIVE: The purpose of the study was to ascertain patients with Nijmegen breakage syndrome (NBS) in the Russian population and characterize the clinical phenotype and molecular genotype of these patients. STUDY DESIGN: Eight unrelated Russian patients with possible diagnoses of NBS were identified. Family histories were collected and clinical and laboratory analyses were carried out. Mutation screening of the NBS1 gene was carried out to confirm the diagnosis in 7 cases. RESULTS: All patients had the key diagnostic features of NBS. One patient had acute myeloblastic leukemia (AML). Two patients had bone marrow aplasia, not previously described as a feature of NBS. Mutation screening of the NBS1 gene revealed that 6 patients were homozygous for the 657del5 mutation, whereas a seventh patient was a compound heterozygote, having the 657del5 mutation and an additional novel mutation, 681delT. CONCLUSIONS: Molecular analyses confirmed the diagnosis of NBS in 7 of the patients. The surprising finding of bone marrow aplasia or AML in 3 of 7 patients raises the possibility of a connection between NBS and another DNA damage disorder, Fanconi anemia.

Chromosomal defects in 34 male homosexuals, half of them with HIV antibodies

Most of the research about viral interactions with human chromosomes was done during the sixties and early seventies and very few was performed after the human immunodeficiency virus (HIV) appearance as an epidemic in the eighties. The objective of this work was to estimate if particular chromosomal changes follow the infection of homosexual males by HIV and to determine if the lifestyle, habits, sexual practices, of our sample of male homosexuals predisposes them to chromosomal abnormalities at a higher rate than the background level of cytogenetic damage the general population has. This was a double blinded case-control study, 17 individuals positive for HIV antibodies (HIV+) detected by enzyme-linked immunosorbent assay (ELISA) and confirmed by western blot (WB) were the cases, and 17 individuals negative for HIV antibodies (HIV-) the controls. These men were a very homogeneous population in terms of age, social status, lifestyles, drug abuse, sexual practices and education. Blood was collected between September 1988 and October 1989. Fresh whole blood was cultured in duplicate for 72 hr. Cell harvest followed conventional methods. Once all cell cultures were gathered, the tubes were picked up at random and air dried chromosome preparations were trypsin-giemsa banded (GTG) after overnight incubation at 60 C degrees. The percentage of gaps and breaks these men had was not different from the reported for the general population, nor were there significant difference among both groups (O.R. = 1.8) in items of amount of chromosomal fragility. The distinction among them was at the level of the specific chromosomal sites where the gaps and breaks located, being sites at 2p21 and at 3p21 four times more frequent among HIV+. These probably represent viral modification sites on chromosomes which are known to look like non-staining gaps which are caused by the virus or viral products. This presumption is supported by an earlier report of repeated breaks at 3p21.1, in fact this was the most common lesion site in this study of chromosomal aberrations of male homosexuals and the authors even considered the probability of "a new type of chromosome marker". Furthermore, years later the CKR5 structural gene was mapped to human chromosome 3p21. This gene codes for the chemokine receptor 5 (CKR5) protein which serves as a secondary receptor on CD4+ T lymphocytes for certain strains of HIV-1. It is possible that this gene was being transcribed in HIV+ men and the cons

[Medical pathology due to trinucleotide repeats]. / Patología médica ocasionada por repetidos de trinucleótidos.

Trinucleotide repeat expansion is responsible for ten human diseases described so far. Four types of repeats are involved in these expansions, with type, number and position in the gene varying from one disease to another. In some fragile sites, the trinucleotide repeat is found to be enlarged to 200 or more. Smaller expansions have been found within coding regions of some genes that are associated with neurodegenerative diseases, such as Huntington's disease. The continuous expansion of the trinucleotide repeats in subsequent generations explains the genetic anticipation, peculiar to these disorders. Recently, it was shown that two expanded minisatellite sequences are also involved in both progressive myoclonus epilepsy type 1 and distamycin A-sensitive fragile site, FRA16B. This form of peculiar heredity is very important because of its relationship with some of the common human degenerative diseases.

Apolipoprotein B genetic variability in Brazilian Indians.

Three apolipoprotein B restriction fragment length polymorphism (RFLPs) (XbaI, MspI, and EcoRI) and the signal peptide insertion-deletion polymorphism were investigated using the polymerase chain reaction in 140 individuals from 5 Brazilian Indian tribes. All studied markers were polymorphic in this ethnic group. The insertion allele 5' beta SP*29 at the signal peptide previously observed in Mexican Americans was detected in about 8% of the chromosomes of 2 tribes (Gavião and Zoró), therefore confirming the Amerindian origin of this allele. Negative linkage disequilibrium was observed between alleles at the signal peptide and the EcoRI polymorphism in all tribes. In 3 populations (Gavião, Suruí, and Zoró) a negative disequilibrium was also detected between the insertion-deletion signal peptide markers and the XbaI polymorphism. In the whole sample of Amerindians 14 of the 24 (58%) possible 4-marker extended haplotypes were identified, but only haplotype 2 (5' beta SP*24/*X+/*M+/*E+) and haplotype 5 (5' beta SP*27/*X-/*M+/*E+) were shared by all tribes. No associations between plasma lipid levels or body mass index and these polymorphisms were observed in this sample.

Spontaneous breakage and fragile site expression in chronic lymphocytic leukemia.

It has been suggested that genetic predisposition to cancer might be related to spontaneous chromosome instability or to fragile site expression. Therefore, spontaneous breakage and fragile sites were analyzed in nine untreated chronic lymphocytic leukemia (CLL) patients to determine their relation to cancer rearrangements. Five cases presented spontaneous gaps and breaks with a random distribution of breakpoints. In cultures treated with fluorodeoxyuridine or aphidicolin, 29 specific bands could be defined as fragile sites. A significant clustering of these sites was found with known common fragile sites (c-fra) and cancer breakpoints described in the literature. Most of these cancer breakpoints were involved in structural abnormalities associated with CLL (p < 0.00001). These data suggest that the expression of specific fragile sites might be related to structural chromosomal aberrations in CLL.

Down's syndrome, ageing and fragile sites.

Fragile sites have been interesting for mapping chromosomal regions involved in disease and ageing. The chromosomal fragile site expression from 38 Down's syndrome (DS) individuals aged 0-48 years was investigated in blood peripheral lymphocytes. Fragile sites were statistically characterized as the minimum expected number of lesions per band based on a Poisson distribution. The results showed that the fragile site 2q11 was associated with the DS condition and fragile sites 5q31, 6p21 and 9q12 with ageing in DS subjects. Fragility in 6p21 has also been associated with Alzheimer's disease patients.

Prevalence of fragile-X syndrome and FRAXE among children with intellectual disability in a Caribbean island, Guadeloupe, French West Indies.

Fragile-X syndrome (FXS) is the most common cause of inherited intellectual disability. Although FXS has been identified in all the main ethnic groups, little is known about its prevalence with respect to ethnicity. Since the identification of the FXS primary defect, diagnosis involving DNA analysis has been made possible, allowing efficient screening strategies to be considered. The present authors have carried out FXS screening among children belonging mainly to the Afro-Caribbean ethnic group (163 boys and 85 girls) affected with moderate to severe intellectual disability of previously unknown origin. We have found a 6.7% and 0% prevalence among boys and girls, respectively, yielding a minimum FXS incidence of 0.42 per 1000 male births per year. Family studies have resulted in genetic counselling for several individuals. FRAXE screening was also achieved and no FRAXE case was detected in this study.

Cytogenetics of three breeds of river buffalo (Bubalus bubalis L.), with evidence of a fragile site on the X chromosome.

The cytogenetic study of 182 river buffalo (Bubalus bubalis L., 2n = 50) of Murrah, Mediterranean and Jaffarabadi breeds, from the State of São Paulo, was carried out to characterize their chromosomes and to detect possible chromosomal abnormalities. The karyotypes were indistinguishable with conventional staining as well as with C and replication R banding techniques. In about 44% of the sample (8 males and 72 females), an X marker chromosome due to a fragile site was shown. The frequency of metaphases expressing the fragility site on the X was highly variable, from 2.86 to 41.03%. In females, the fragile site, rarely appeared on both X chromosomes. Most of the metaphases showed only 1 marker chromosome. In R-banded metaphases using 5-bromodeoxyuridine (BrdU) treatment, it corresponded in general to the late replicating X chromosome. No correlation between the X fragile site and altered phenotype was found. Structural and numerical chromosome rearrangements were ruled out in the present sample of buffalo.

Expresión de sitios frágiles en neoplasias mieloides / Fragile site expression in myeloid leukemias

El objetivo del presente trabajo fue evaluar la expresión de sitios frágiles (SF) en pacientes con leucemia mieloide crónica (LMC) y leucemia mieloblástica aguda (LMA) a fin de establecer si expresan SF constitucionales en los mismos puntos de ruptura de las alteraciones cromosómicas presentes en el tejido neoplásico. Se estudiaron 9 pacientes con LMA, 7 con LMC y 7 individuos sanos. Se determinó el cariotipo en médula ósea y se indujo la expresión de SF con FUDR (10 µg/ml) y BUDR (50 µg/ml) en sangre periférica. El estudio citogenético de médula ósea demostró que todos los casos de LMC presentaron la t(9;22)(q34;q11). En LMA se encontraron 4 individuos con cariotipo normal y los restantes presentaron las siguientes alteraciones clonales: t(3;8)(q11;q13), del (5)(p11), t(3;11)(q21;p15), inv(16)(p13;q22), t(9;22) y del (9q). En los pacientes con LMC no se encontraron SF en las bandas 9q34 ó 22q11, involucradas en el cromosoma Phû. Tampoco se identificaron SF en los puntos de ruptura implicados en AC estructurales de los pacientes con LMA. Estos resultados sugerirían que los SF no estarían involucrados con el origen de los marcadores cromosómicos hallados en estas neoplasias.