Fanconi anemia gene-associated germline predisposition in aplastic anemia and hematologic malignancies / 医学前沿

Whether Fanconi anemia (FA) heterozygotes are predisposed to bone marrow failure and hematologic neoplasm is a crucial but unsettled issue in cancer prevention and family consulting. We retrospectively analyzed rare possibly significant variations (PSVs) in the five most obligated FA genes, BRCA2, FANCA, FANCC, FANCD2, and FANCG, in 788 patients with aplastic anemia (AA) and hematologic malignancy. Sixty-eight variants were identified in 66 patients (8.38%). FANCA was the most frequently mutated gene (n = 29), followed by BRCA2 (n = 20). Compared with that of the ExAC East Asian dataset, the overall frequency of rare PSVs was higher in our cohort (P = 0.016). BRCA2 PSVs showed higher frequency in acute lymphocytic leukemia (P = 0.038), and FANCA PSVs were significantly enriched in AA and AML subgroups (P = 0.020; P = 0.008). FA-PSV-positive MDS/AML patients had a higher tumor mutation burden, higher rate of cytogenetic abnormalities, less epigenetic regulation, and fewer spliceosome gene mutations than those of FA-PSV-negative MDS/AML patients (P = 0.024, P = 0.029, P = 0.024, and P = 0.013). The overall PSV enrichment in our cohort suggests that heterozygous mutations of FA genes contribute to hematopoietic failure and leukemogenesis.

Acute lymphoblastic leukemia in a child with fanconi's anaemia

Fanconi anaemia [FA] is an autosomal recessive inherited disorder with progressive bone marrow failure, associated congenital malformation and solid and haematological malignancies. Acute myeloid leukemia is the commonest haematological malignancy followed by myelodysplastic syndrome in children with FA. FA transformed into acute lymphoblastic leukemia [ALL] is a rare phenomenon and one of the rarest haematological malignancies associated with this disorder. We are reporting a 13 years old girl with FA and positive chromosomal breakage. She required regular blood product transfusion. She was planned for haematopoietic stem cell transplantation [HSCT] but the sibling-matched donor was found to have chromosomal breaks as well. Later on, her peripheral smear showed blast cell. Bone marrow showed pre-B ALL. She was started on chemotherapy but died shortly due to complications of the treatment. For this rare condition conservative management is indeed essential, however, safe and appropriate chemotherapy regimen is needed

Evaluation of concentration and storage effects of mitomycin C in the diagnosis of Fanconi anemia among idiopatic aplastic anemia patients.

BACKGROUND: Fanconi anemia (FA) is a rare autosomal recessive genetic disorder that shows an increased sensitivity to the intercalating agents such as mytomycin C (MMC), measured as chromosomal aberrations. This study was conducted to differentiate between FA and “idiopathic” aplastic anemia on the basis of induced chromosomal breakage study with MMC. MATERIALS AND METHODS: MMC stress tests in different final concentrations of 20 and 50 ng/ml of MMC were conducted on peripheral blood lymphocytes from 32 patients with aplastic anemia and 13 healthy controls. Fifty nanograms per milliliter of MMC from old, fresh and frozen stocks was used to check the sensitivity of diagnosis on FA-diagnosed patients. Statistical analysis was used for the assessment of aberrations, including chromatid and chromosome breaks and exchanges. RESULTS: Eight patients (25%) with a very high percentage of chromosomal breakage were diagnosed as FA on the basis of the chromosomal breakage study. Six of these patients exhibited congenital anomalies at presentation, while another two lacked such anomalies or had minor physical problems. Freshly made MMC has shown more sensitivity to detect FA patients compared with frozen or 1-week-old MMC stock. CONCLUSIONS: The study indicates that freshly made MMC stress test provides an unequivocal means of differentiation between FA and “idiopathic” aplastic anemia. Further, the study, the first of its kind from Iran, stresses on the need for conducting this test in all aplastic anemia cases, even those without congenital anomalies, for accurate and timely diagnosis of FA to implement appropriate therapy.

Incidence of malignancy and clonal chromosomal abnormalities in Fanconi anemia.

Background: Fanconi anemia (FA) is an autosomal recessive, cancer susceptibility disorder characterized by diverse clinical features, such as short stature, skeletal or skin abnormalities, progressive bone marrow (BM) failure, and increased risk of malignancies. Clonal chromosomal abnormalities are frequently reported in FA patients transformed to myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Aim: To study the incidence of malignancy and clonal chromosomal abnormalities in FA patients. Materials and Methods: Thirty-eight clinically diagnosed FA patients were studied at the time of diagnosis and the patients were followed-up for a maximum of 28 months at 3-month intervals. The median duration of follow-up of these patients was 19.8 months. Chromosomal breakage investigation using mitomycin C (MMC)- and diepoxybutane (DEB)-induced peripheral blood cultures were stimulated with phytohemagglutinin. Cytogenetic study was done on the BM cells to detect clonal chromosomal aberrations. Results: Eleven (28.95%) out of 38 patients developed malignancies, including 6 (54.54%) MDS, 4 (36.36%) AML, and 1 (2.63%) squamous cell carcinoma. The clonal chromosomal abnormalities were detected in 5 (45.45%) FA patients who developed malignancies and the type of chromosomal abnormality detected were monosomies 5, 7, trisomy 10, dup(1)(q12-q24), and inv(7)(p11pter). Conclusion: The FA patients have a high risk of developing malignancies, and clonal chromosomal abnormalities play an important role in the prognosis of the disease. Therefore, FA patients need to be followed-up at regular intervals for early diagnosis and optimal management of the disease.

FANCD2 Western blot as a diagnostic tool for Brazilian patients with Fanconi anemia

Fanconi anemia is a rare hereditary disease showing genetic heterogeneity due to a variety of mutations in genes involved in DNA repair pathways, which may lead to different clinical manifestations. Phenotypic variability makes diagnosis difficult based only on clinical manifestations, therefore laboratory tests are necessary. New advances in molecular pathogenesis of this disease led researchers to develop a diagnostic test based on Western blot for FANCD2. The objective of the present study was to determine the efficacy of this method for the diagnosis of 84 Brazilian patients with Fanconi anemia, all of whom tested positive for the diepoxybutane test, and 98 healthy controls. The FANCD2 monoubiquitinated isoform (FANCDS+/FANCD2L-) was not detected in 77 patients (91.7 percent). In 2 patients (2.4 percent), there was an absence of both the monoubiquitinated and the non-ubiquitinated proteins (FANCD2S-/FANCD2L-) and 5 patients (5.9 percent) had both isoforms (FANCD2S+/FANCD2L+). This last phenotype suggests downstream subtypes or mosaicism. All controls were diepoxybutane negative and were also negative on the FANCD2 Western blot. The Western blot for FANCD2 presented a sensitivity of 94 percent (79/84) and specificity of 100 percent (98/98). This method was confirmed as an efficient approach to screen Brazilian patients with deleterious mutations on FANCD2 (FANCD2S-/FANCD2L-) or other upstream genes of the FA/BRCA pathway (FANCDS+/FANCD2L-), to confirm the chromosome breakage test and to classify patients according to the level of FA/BRCA pathway defects. However, patients showing both FANCD2 isoforms (FANCD2S+/FANCD2L+) require additional studies to confirm mutations on downstream Fanconi anemia genes or the presence of mosaicism.

Correlation of thyroid and growth hormones to chromosomal instability in Egyptian Fanconi anemia patients.

OBJECTIVE: Fanconi anemia (FA) is a rare inherited genomic instability syndrome and usually associated with endocrine dysfunctions. We aimed to assess the diagnostic standards of chromosomal instability in FA and to correlate the breakage frequency with the severity of endocrinal dysfunctions. METHODS: Twenty seven FA patients were randomly selected from Hematology Unit of Mansoura University Children's Hospital; their mean age 8.8 yr. Sixteen normal children matched for age and sex were used as controls. Cytogenetic studies included peripheral blood lymphocyte cultures using phytohemagglutinin to obtain chromosomal spreads. Chromosomal breakage was induced by (i) Diepoxybutane 0.1 mug/ml. (ii) Mitomycin C 0.1 microg/ml. (iii) Irradiation of cultures to four radiation doses; 75, 150, 300 and 400 rads (rad1, rad2, rad3 and rad4 respectively). Chromosomal aberrations were scored from the previous 6 cultures besides a culture for spontaneous chromosomal breakage; then mean chromosomal breakage was calculated for the seven cultures. Endocrinal evaluation included quantitative determination of thyroid stimulating hormone (TSH) and tetraiodothyronine (T4), serum growth hormone (GH), insulin like growth factor-1 (IGF-1) and insulin levels. RESULTS: Chromosomal breakage was found to be significantly higher in patients than control when induced by Diepoxybutane (p = 0.003), Mitomycin (p = 0.001), rad3 (p = 0.043) and rad4 (p = 0.001). Mean chromosomal breakage was significantly negative correlated to head circumference (r = -0.57) and GH level (r = -0.50), with no significant correlation to other hormonal parameters. Mitomycin and rad4 were found more accurate than DEB test for diagnosis of FA in suspected cases. CONCLUSION: Correction of the frequently associated hormonal dysfunction (reduced GH and T4) should be considered in the treatment discipline of FA patients to improve their final height.

Differentiation of Fanconi and aplastic anemia using chromosomal breakage test in Southern Iran

Fanconi anemia [FA] is a chromosomal breakage disorder characterized by familial aplastic anemia [AA], various congenital anomalies, and a characteristic chromosomal response to clastogenic stress. In this study, chromosome breakage test was performed for 38 patients suspected of having FA and age-matched controls. According to the results, ten patients were considered as FA cases and 15 patients with no chromosomal breaks were considered as AA. Differentiation of FA from AA is very important because the primary treatment is different. This test should be done in every primary presentation of AA

Frequency of Fanconi anemia in Brazil and efficacy of screening for the FANCA 3788-3790del mutation

Fanconi anemia (FA) is an autosomal recessive genetic disease characterized by progressive bone marrow failure, susceptibility to cancer and multiple congenital anomalies. There is important clinical variability among patients and the knowledge of factors which might predict outcome would greatly help the decision making regarding the choices of treatment and the appropriate time to start it. Future studies of the possible correlation between specific mutations with specific clinical presentations will provide the answer to one of these factors. At our Center we standardized a rapid and precise screening test using a mismatch PCR assay for a specific mutation (3788-3790del in exon 38 of gene FANCA) in Brazilian FA patients. We present the results obtained after screening 80 non-consanguineous FA patients referred from all regions of Brazil with a clinical diagnosis of FA supported by cellular hypersensitivity to diepoxybutane. We were able to detect the 3788-3790del allele in 24 of the 80 (30 percent) FA patients studied. Thirteen of the 80 (16.25 percent) were homozygotes and 11 of the 80 (13.75 percent) were compound heterozygotes, thus confirming the high frequency of the FANCA 3788-3790del mutation in Brazilian FA patients. The identification of patients with specific mutations in the FA genes may lead to a better clinical description of this condition, also providing data for genotype-phenotype correlations, to a better understanding of the interaction of this specific mutation with other mutations in compound heterozygote patients, and ultimately to the right choices of treatment for each patient with improvement of the prognosis on future studies.

Anemia de Fanconi: revisión / Fanconi anemia: review

La Anemia de Fanconi es un síndrome de fragilidad cromosómica, autosómico recesivo, caracterizado por presentar malformaciones congénitas muy diversas y en diferentes órganos en el 70 por ciento de los casos; insuficiencia medular progresiva y tendencia a enfermedades malignas: sobre todo leucemia mieloide aguda y tumores sólidos. La afección fue descrita en 1927 por el pediatra suizo, Guido Fanconi, en tres hermanos con diferentes malformaciones congénitas, astenia, infecciones de repetición y sangrados espontáneos por fallo en la función de la médula ósea. El diagnóstico precoz permite un buen control del compromiso hematológico; la realización de los tratamientos quirúrgicos antes de la instauración de la trombopenia; consejo genético para la familia; la identificación presintomática de hermanos afectados o de embarazos cuyos fetos sean posibles donantes de progenitores hematopoyéticos para un hermano comprometido.

Body proportions in Fanconi anemia heterozygotes.

To study the anthropometric ratios in parents (heterozygotes) of children with Fanconi anemia. The study was carried out in the Department of Hematology, Institute of Child Health & Hospital for Children, Chennai. Parents of children with Fanconi anemia were the subjects of the study. Applying standard instruments and methods, various body measurements were recorded. 31 fathers and 37 mothers were included in the study. A hundred male and female controls of the same ethnic group were also studied for the same parameters. The ratios were calculated and statistically analyzed. It was observed that fathers (male heterozygotes) had shorter forearms, the ratio of upper arm: forearm was significantly increased compared to male controls. In mothers (female heterozygotes) the inter-pupillary distance was increased, the ratio of head circumference to inter-pupillary distance was decreased compared to female controls.

Variabilidad clínica citogenética en doce familias mexicanas con anemia de Fanconi y su relación con el grupo de complementación al que pertenecen / Clinical and cytogenetic variability on twelve Fanconi anemia families and its relationship with complementation group assignment

Objetivo. Describir las caractetísticas clínica y citogenéticas en pacientes mexicanos con anemia de Fanconi y determinar si la variabilidad fenotípica se relaciona con el grupo de complementación. Material y métodos. Se hizo el diagnóstico citogenético por exposición de linfocitos de sangre periférica a mitomicina C y a diepoxibutano. Se clasificaron, la gravedad de la anemia y las manifestaciones clínica utilizando las puntuaciones de alter y Auerbach respectivamente. Se establecieron líneas linfoblastoides de ocho individuos y se determinó el grupo de complementación mediante fusión celular en cuatro casos índices. Resultados. se estudiaron 12 familias con 25 afectados. Los pacientes mostraron frecuencias elevadas de aberraciones cromosómicas espontáneas e inducidas; no existió relación con la gravedad clínica o estado anémico. El cuadro clínico se clasificó como grave en 12 pacientes y como leve en 13. La anemia no se presentó en tres enfermos, fue leve en 13, moderadas en siete y grave en uno. La mortalidad fue del 32 por ciento (8/25). No hubo relación entre puntuación clínica, grado de anemia y defunción. Once pacientes se asignaron al grupo de complementación A con cuadro clínico y anemia leves; sus resultados citogenéticos mostraron variabilidad. Un paciente fue asignado al grupo C, obtuvo una puntuación clínica grave, anemia dependiente de transfusión y alta sensibilidad a mutágenos. Trece sujetos no fueron clasificados, en tres pacientes se obtuvo una línea linfoblastoide resistente a mitomicina C, que sugirió mosaicismo somático. Conclusiones. El grupo de complementación no explica la variabilidad; existen otros factores como el mosaicismo somático que modifica el fenotipo celular

Anemia de fanconi: presentación de un caso / Fanconi's anemia: presentation of a case

La anemia de Fanconi es un desorden cromosómico caracterizado por una anemia aplástica familiar de carácter autosómico recesivo, que se manifiesta clínicamente con lesiones de piel, anormalidades congénitas de tipo esquelético, genitourinario y neuroocular, de baja prevalencia mundial. Se presenta un caso de anemia de Fanconi diagnósticado en un preescolar masculino de 33 meses de edad, hospitalizado en el Servicio de Pediatría del Hospital General "Patrocinio Peñuela Ruíz" de San Cristóbal. Se analizan los hallazgos clínicos y aspectos diagnósticos y terapéuticos de esta enfermedad

Chromosome fragility in hematologic disease presumably induced by environmental pollutants

Chromosome instability consists of chromosome abnoprmalities as multiple breaks in in metaphase chromosomes in syndromes of chromosaome instability such as fanconi's anemia (FA) which is mainly characaterized by bone marrow aplasia; some cases progress to acute leukemia. FA is a hereditary disease with recessive and monogenic transmission. This pair of mutated genes is related to chromosome fragility and therefore is responsible for the inefficiency of DNA repair. In normal individuals, these genes are assumed to be expressed normally, but their products ara insufficient to perform DNA repair when the intensity of the polluting agent lelads to exposure above basal levels. In the present study, the bone marrow of four patients with different hematologic diseases was submitted to cytogenetic analysis. Two had aplastic anemia, and one bad lymphoblastic leukemia. These patients were from towns unb the Amazon Region where the mercuri used for gold prospecting and the substances used and/or released in aluminium mining have been introduced into the environment. The last patient had fanconi's anemia and was used as a model in the discussion of the results. The cytogenetic findings were similar for all patients, the major ones being chromosome fragmentation and pulverization. In view of these findings, we believe that chromosome fragility, observed in the first three patients, presumably was induced by environmental pllutants

Anemia de Fanconi: a propósito de un paciente / Fanconi's Anemia

La anemia de Fanconi, entidad autosómica recesiva se caracteriza por pancitopenia, malformaciones congénitas e inestabilidad cromosómica; las manifestaciones clínicas suelen iniciarse a los seis años de edad. Se presenta un paciente de 19 meses de edad cuyo diagnóstico se estableció en fase preanémica. Se discuten aspectos génicos y cromosómicos de la entidad y la importancia de establecer el diagnóstico en etapa temprana.

Estudio de heterogeneidad genética en anemia de Fanconi por medio de la adición del plasma / Genetic heterogenicity study in Fanconis anemia by the addition of plasma

Con el objetivo de investigar heterogeneidad genética en la variedad infantil de anemia de Fanconi (AF) se realizaron cultivos de linfocitos de pacientes con Af con plasma autólogo, con plasma de otros pacientes con AF y con plasma normal. Se sembraron además linfocitos de un sujeto normal con plasma autólogo y con plasma de cada uno de los pacientes con AF. Para cada tipo de cultivo se cuantificó la freuencia de aberraciones cromossómicas inducidas por MMC. Los linfocitos de pacientes con AF cultivados con plasma autólogo mostraron hipersensibilidad a la MMC y una disminución significativa de la frecuencia de aberraciones inducidas en los cultivos con plasma normal. Sin embargo, en presencia del plasma de los otros pacientes la gran variabilidad en la respuesta de los linfocitos de los pacientes con AF a la MMC no permitió demostrar heterogeneidad genética. Esto pudiera deberse a que a pesar de existir heterogeneidad genética la metodología empleada no pudiera evidenciarla o bien, a que nuestros pacientes correspondiean ala mismo tipo de AF