JAK2 V617F mutation is a rare event in juvenile myelomonocytic leukemia.
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Biomedical subjects
Publications and source records attributed to C Danesino.
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Familial haemophagocytic lymphohistiocytosis (FHL) is a genetically heterogeneous disorder characterised by constitutive defects in cellular cytotoxicity resulting in fever, hepatosplenomegaly and cytopenia, and the outcome is fatal unless treated by chemoimmunotherapy followed by haematopoietic stem-cell transplantation. Since 1999, mutations in the perforin gene giving rise to this disease have been identified; however, these account only for 40% of cases. Lack of a genetic marker hampers the diagnosis, suitability for transplantation, selection of familial donors, identification of carriers, genetic counselling and prenatal diagnosis. Mutations in the Munc13-4 gene have recently been described in patients with FHL. We sequenced the Munc13-4 gene in all patients with haemophagocytic lymphohistiocytosis not due to PRF1 mutations. In 15 of the 30 families studied, 12 novel and 4 known Munc13-4 mutations were found, spread throughout the gene. Among novel mutations, 2650C-->T introduced a stop codon; 441del A, 532del C, 3082del C and 3226ins G caused a frameshift, and seven were mis sense mutations. Median age of diagnosis was 4 months, but six patients developed the disease after 5 years of age and one as a young adult of 18 years. Involvement of central nervous system was present in 9 of 15 patients, activity of natural killer cells was markedly reduced or absent in 13 of 13 tested patients. Chemo-immunotherapy was effective in all patients. Munc13-4 mutations were found in 15 of 30 patients with FHL without PRF1 mutations. Because these patients may develop the disease during adolescence or even later, haematologists should include FHL2 and FHL3 in the differential diagnosis of young adults with fever, cytopenia, splenomegaly and hypercytokinaemia.
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Hereditary haemorrhagic telangiectasia is a genetic disease characterised by the presence of teleangiectases virtually involving every organ. Hepatic involvement is represented by a spectrum of vascular abnormalities, which evolve in a continuum from tiny teleangiectases to substantial vascular malformations, potentially with a progressively greater arteriovenous shunt. Liver involvement in hereditary haemorrhagic telangiectasia is almost always asymptomatic; on the other hand, hepatic vascular malformations can induce severe complications, depending on the predominant venous side of the arteriovenous fistulas-high-output cardiac failure in the case of hepatohepatic fistulas, and portal hypertension in the case of hepatoportal fistulas. Doppler sonography can detect and stage hepatic vascular malformations in subjects with hereditary haemorrhagic telangiectasia; according to Doppler sonographic grading, appropriate advice for follow-up and/or therapy can be given.
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The role of GH in carcinogenesis is unclear. We studied the effect of recombinant human GH (rhGH) in vitro on chromosomal and genomic instability. Thirteen children, aged 9.57 +/- 1.08 yr (mean +/- SEM), with complete (no.=5) or partial (no.=8) GH deficiency were evaluated before and during GH treatment. We examined the incidence of chromosome and chromatid breaks, and microsatellite instability after in vitro addition of two different doses of rhGH to peripheral blood lymphocytes obtained from the patients. No differences were observed between the samples of GH-deficient children before and after GH therapy as regards the percentage of chromosome and chromatids breaks, and in microsatellite instability. Our data show that in vitro addition of rhGH does not induce chromosomal and/or genomic instability in cultured lymphocytes.
AIMS: In previous studies, the prevalence of hepatic vascular malformations (VMs) in a large Italian family with hereditary hemorrhagic telangiectasia (HHT) was examined by Doppler ultrasonography (US) as screening technique, and the relevant Doppler US findings were described and classified. Thereafter, Doppler US has been routinely used to screen HHT families for liver involvement. Hepatic VMs were evaluated and classified on the basis of Doppler US findings. METHODS: Three hundred and forty-six subjects belonging to 64 pedigrees were checked for the presence of signs of HHT. All of them underwent abdominal Doppler US screening for hepatic VMs. Vascular abnormalities were classified as minimal if the hepatic artery was dilated in extrahepatic tract only and measured > 6 mm; as moderate if the hepatic artery was dilated in both intra and extrahepatic tract; and as severe if complex changes of the arterial hepatic branches were associated with hepatic and/or portal vein dilatation. Furthermore, Doppler parameters, both qualitative (flow direction, turbulence) and quantitative (peak flow velocity and resistivity index in hepatic artery, mean velocity in portal vein, diastolic peak flow velocity in hepatic veins), were entered into our VM classification. RESULTS: HHT was found in 222 subjects, with hepatic VMs detected by Doppler US in 92 (41.4 %) (24 males, 68 females, mean age 52.2). Hepatic VMs were minimal in 11 subjects, moderate in 70, and severe in 11. CONCLUSIONS: On the basis of our proposed grading, hepatic VMs can be easily classified in subjects with HHT by Doppler US. Depending on the degree of hepatic vascular derangement, appropriate programs for follow up and/or therapy can be designed.
Langerhans cell histiocytosis (LCH), characterised by the infiltration of one or more organs by large mononuclear cells, can develop in persons of any age. Although the features of this disease are well described in children, they remain poorly defined in adults. From January 2000 to June 2001, 274 adults from 13 countries, with biopsy-proven adult LCH, were registered with the International Histiocyte Society Registry. Information was collected about clinical presentation, family history, associated conditions, cigarette smoking and treatment, to assist in future management decisions in patients aged 18 years and older. There were slightly more males than females (143:126), and the mean ages at the onset and diagnosis of disease were 33 years (standard deviation (S.D.) 15 years) and 35 years (S.D. 14 years), respectively. 2 patients had consanguineous parents, and 1 had a family history of LCH; 129 reported smoking (47.1%); 17 (6.2%) had been diagnosed with different types of cancer. Single-system LCH, found in 86 patients (31.4%), included isolated pulmonary involvement in 44 cases; 188 patients (68.6%) had multisystem disease; 81 (29.6%) had diabetes insipidus. Initial treatment consisted of vinblastine administered with or without steroids, to 82 patients (29.9%), including 9 who had received it with etoposide, which was the sole agent given to 19 patients. 236 patients were considered evaluable for survival. At a median follow-up of 28 months from diagnosis, 15 patients (6.4%) had died (death rate, 1.5/100 person years, 95% Confidence Interval (95% CI) 0.9-2.4). The probability of survival at 5 years postdiagnosis was 92.3% (95% CI 85.6-95.9) overall, 100% for patients with single-system disease (n=37), 87.8% (95% CI 54.9-97.2) for isolated pulmonary disease (n=34), and 91.7% (95% CI 83.6-95.9) for multisystem disease (n=163). Survival did not differ significantly among patients with multisystem disease, with or without liver or lung involvement) 5-year survival 93.6% (95% CI 84.7-97.4) versus 87.5% (95% CI 65.5-95.9), respectively; P value 0.1). LCH in adults is most often a multisystem disease with the highest mortality seen in patients with isolated pulmonary involvement. It should be included in the differential diagnosis of disseminated or localised disease of the bone, skin and mucosa, as well as the lung and the endocrine and central nervous system, regardless of the age of the patient. A prospective international therapeutic study is warranted.
Nijmegen breakage syndrome (NBS) is a rare, autosomal-recessive chromosome instability disorder characterized by growth and developmental defects, immunodeficiency, high susceptibility to lymphoid malignancies, hypersensitivity to ionizing radiation and aberrant cell-cycle checkpoint control. The disease is caused by mutations in the NBS1 gene, which encodes nibrin, a component of the hMre11-Rad50-p95 complex involved in cellular response to DNA double-strand breaks. Genetic heterogeneity has been suggested in at least two patients with the NBS phenotype, but no mutation in the NBS1 gene; recently, mutations in the gene encoding the enzyme ligase IV have been identified in patients with signs of NBS. We describe a boy with an NBS clinical phenotype but no mutation in either the NBS1 or the LIG4 genes. The analysis of his cellular phenotype reveals chromosome instability and radiosensitivity, but normal cell-cycle checkpoint control. In addition, a literature review was carried out to summarize and compare data of all NBS-like patients reported to date. This case confirms genetic heterogeneity for NBS. We believe that dissecting the clinical and cellular phenotypes of this and other NBS-like patients will provide useful information for the research of new genes involved in cellular response to DNA damage and the assessment of cancer risk in NBS-like syndrome.
Griscelli syndrome (GS) is a rare autosomal recessive disorder, characterized by pigmentary dilution of the skin and hair and in most patients by abnormal regulation of the immune system, which results in a syndrome of macrophage hyperactivation, known as hemophagocytic lymophohistiocytosis (HLH). Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment available for genetically induced HLH. Few cases of successful HSCT from a compatible donor have been reported in children with GS. We describe the first patient with GS cured with an allograft from a compatible unrelated bone marrow donor. We used a novel preparative regimen consisting of busulfan, thiotepa and fludarabine. The demonstrated curative effect of HSCT from an unrelated donor in a patient with genetically determined HLH also supports the use of a systematic diagnostic approach in these patients, in order to identify those with a worse prognosis and needing an urgent allograft in a timely manner.
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The Stickler syndrome is among the most common heritable disorders of connective tissue. The syndrome fully expressed clinical phenotype includes the degeneration of the vitreous gel and retina, frequently associated with myopia, accompanied by non-ocular features, such as craniofacial dysmorphisms or malformations, hearing impairment, skeletal dysplasia and progressive arthropathy. So far, mutations at three collagen loci, COL2A1, COL11A1 and COL11A2, have been found in Stickler syndrome patients, with about two thirds of investigated familial cases found to be associated to COL2A1 gene mutations. We report on a three generation family in which a diagnosis of Stickler syndrome was made and linkage analysis suggested COL2A1 to be the causing gene. These data permitted us to perform two prenatal diagnosis analysing the 3'VNTR polymorphism of the involved gene on amniocytes' DNA and to provide the family with genetic counselling and paediatric support at the delivery.
The hemophagocytic lymphohistiocytoses (HLH) comprise a heterogeneous group of disorders characterized by dysregulated activation of T cells and macrophages. Although some patients with HLH harbor perforin gene mutations, the cause of the remaining cases is not known. The phenotype of HLH bears a strong resemblance to X-linked lymphoproliferative disease (XLP), an Epstein-Barr virus (EBV)-associated immunodeficiency resulting from defects in SH2D1A, a small SH2 domain-containing protein expressed in T lymphocytes and natural killer cells. Here it is shown that 4 of 25 male patients with HLH who were examined harbored germline SH2D1A mutations. Among these 4 patients, only 2 had family histories consistent with XLP. On the basis of these findings, it is suggested that all male patients with EBV-associated hemophagocytosis be screened for mutations in SH2D1A. Patients identified as having XLP should undergo genetic counseling, and be followed long-term for development of lymphoma and hypogammaglobulinemia.
Two sisters are reported, both with a myelodysplastic syndrome (MDS) associated with partial monosomy 7. A trisomy 8 was also present in one of them, who later developed an acute myeloid leukemia (AML) of the M0 FAB-type and died, whereas the other died with no evolution into AML. Besides FISH studies, microsatellite analysis was performed on both sisters to gather information on the parental origin of the chromosome 7 involved in partial monosomy and of the extra chromosome 8. The chromosomes 7 involved were of different parental origin in the two sisters, thus confirming that familial monosomy 7 is not explained by a germ-line mutation of a putative tumor-suppressor gene. Similar results were obtained in two other families out of the 12 reported in the literature. Noteworthy is the association with a mendelian disease in 3 out of 12 monosomy 7 families, which suggest that a mutator gene, capable of inducing both karyotype instability and a mendelian disorder, might act to induce chromosome 7 anomalies in the marrow. We postulate that, in fact, an inherited mutation in any of a group of mutator genes causes familial monosomy 7 also in the absence of a recognized mendelian disease, and that marrow chromosome 7 anomalies, in turn, lead to MDS/AML.
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Trisomic cells in neoplasms may represent abnormal clones originated from a tissue-confined mosaicism, and arise therefore by a meiotic error. We report on a 16-month-old child with erythroleukaemia (AML-M6), whose marrow karyotype at onset was 48,XX,del(13)(q12q14),del(14)(q22q32),+21,+21. The parental origin of the supernumerary chromosomes 21 was investigated by comparing 10 polymorphic loci scattered along the whole chromosome on the patient's marrow and her parents' leukocytes. Three loci were informative for the presence of three alleles, two of which were of maternal origin; two further loci showed a maternal allele of higher intensity. Lymphocytes and skin fibroblasts showed a normal karyotype, and molecular analysis on leukocytes at remission, buccal smear and urinary sediment cells consistently showed only one maternal allele, whereas neonatal blood from Guthrie spot showed two maternal alleles as in the marrow. An accurate clinical re-evaluation confirmed a normal phenotype. Our results indicate that tetrasomy 21 arose from a marrow clone with trisomy 21 of meiotic origin. To the best of our knowledge, this is the first evidence that supernumerary chromosomes in neoplastic clones may in fact be present due to a meiotic error. This demonstrates that a tissue-confined constitutional mosaicism for a trisomy may indeed represent the first event in multistep carcinogenesis.
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