High penetrance of myeloid neoplasia with diverse clinical and cytogenetic features in three siblings with a familial GATA2 deficiency.

Pathogenic germ-line variants in GATA2 (GATA2-deficiency) can cause childhood myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML), and can be associated with distinct clinical syndromic features. However, penetrance and genotype-phenotype correlations are incompletely understood. Here we report on the clinically diverse features of three siblings affected by GATA2c.1021_1031del over an 18-year period, all initially presenting in childhood and adolescence with MDS and AML with monosomy 7 (-7), and one also with trisomy 8 (+8). The siblings inherited a GATA2c.1021_1031del from their father who remains asymptomatic in his sixth decade. The two younger sisters are well after unrelated haematopoietic stem cell transplantation (HSCT), while the first boy died of severe chronic lung disease after sibling HSCT from his youngest sister, who subsequently also developed GATA2-deficiency associated MDS. This family illustrates high penetrance with variable genotype/phenotype correlation within one generation with GATA2-deficiency. We surmise that the lung disease post sibling HSCT was also caused by the GATA2-deficiency. The experience with this family underlines the necessity for GATA2 analysis in all apparently sporadic childhood and teenage MDS and AML with -7 also in the absence of a family history or other clinical features, and rigorous genetic testing in siblings. Moreover, our findings support the arguments for pre-emptive HSCT in variant-carrying siblings.

Heterozygote FANCD2 mutations associated with childhood T Cell ALL and testicular seminoma.

Fanconi anaemia (FA) is an inherited disease with congenital and developmental abnormalities characterised by cellular cross linker hypersensitivity. FA is caused by mutations in any of so far 15 identified FANC genes, which encode proteins that interact in a common DNA damage response (DDR) pathway. Individuals with FA have a high risk of developing acute myeloid leukaemia (AML) and squamous cell carcinoma. An increased cancer risk has been firmly established for carriers of mutations in FANCD1/BRCA2, FANCJ/BRIP1, FANCN/PALB2, RAD51C/FANCO and link the FA pathway to inherited breast and ovarian cancer. We describe a pedigree with FANCD2 mutations c.458T > C (p.Leu153Ser) and c.2715 + 1G > A (p.Glu906LeufsX4) with mild phenotype FA in the index case, T cell ALL in the Leu153Ser heterozygous brother and testicular seminoma in the p.Glu906LeufsX4 heterozygous father. Both FANCD2 alleles were present in the T Cell ALL and the seminoma. This links specific FANCD2 mutations to T cell ALL and seminoma without evidence of allelic loss in the tumour tissue.

Amplification and translocation of 3q26 with overexpression of EVI1 in Fanconi anemia-derived childhood acute myeloid leukemia with biallelic FANCD1/BRCA2 disruption.

Fanconi anemia (FA) is an inherited disease with congenital abnormalities and an extreme risk of acute myeloid leukemia (AML). Genetic events occurring during malignant transformation in FA and the biology of FA-associated AML are poorly understood, but are often preceded by the development of chromosomal aberrations involving 3q26-29 in bone marrow of FA patients. We report here the molecular cytogenetic characterization of FA-derived AML cell lines SB1685CB and SB1690CB by conventional and array comparative genomic hybridization, fluorescence in situ hybridization, and SKY. We identified gains of a 3.7 MB chromosomal region on 3q26.2-26.31, which preceded transformation to overt leukemia. This region harbors the oncogenic transcription factor EVI1. A third FA-derived cell line, FA-AML1, carried a translocation with ectopic localization of 3q26 including EVI1. Rearrangements of 3q, which are rare in childhood AML, commonly result in overexpression of EVI1, which determines specific gene expression patterns and confers poor prognosis. We detected overexpression of EVI1 in all three FA-derived AML. Our results suggest a link between the FA defect, chromosomal aberrations involving 3q and overexpression of EVI1. We hypothesize that constitutional or acquired FA defects might be a common factor for the development of 3q abnormalities in AML. In addition, cryptic imbalances as detected here might account for overexpression of EVI1 in AML without overt 3q26 rearrangements.

Spectrum and significance of variants and mutations in the Fanconi anaemia group G gene in children with sporadic acute myeloid leukaemia.

Childhood acute myeloid leukaemia (AML) is uncommon. Children with Fanconi anaemia (FA), however, have a very high risk of developing AML. FA is a rare inherited disease caused by mutations in at least 12 genes, of which Fanconi anaemia group G gene (FANCG) is one of the commonest. To address to what extent FANCG variants contribute to sporadic childhood AML, we determined the spectrum of FANCG sequence variants in 107 children diagnosed with sporadic AML, using polymerase chain reaction (PCR), fluorescent single-strand conformational polymorphism (SSCP) and sequencing methodologies. The significance of variants was determined by frequency analysis and assessment of evolutionary conservation. Seven children (6.5%) carried variants in FANCG. Two of these carried two variants, including the known IVS2 + 1G>A mutation with the novel missense mutation S588F, and R513Q with the intronic deletion IVS12-38 (-28)_del11, implying that these patients might have been undiagnosed FA patients. R513Q, which affects a semi-conserved amino acid, was carried in two additional children with AML. Although not significant, the frequency of R513Q was higher in children with AML than unselected cord bloods. While FANCG mutation carrier status does not predispose to sporadic AML, the identification of unrecognised FA patients implies that FA presenting with primary AML in childhood is more common than suspected.

The impact of monitoring Epstein-Barr virus PCR in paediatric bone marrow transplant patients: can it successfully predict outcome and guide intervention?

BACKGROUND: Epstein-Barr virus (EBV) associated lymphoproliferative disease is a complication of haemopoietic stem cell transplantation (HSCT). In certain groups (unrelated and mismatched donor transplants, T-cell depleted) the risk may be as high as 25% with significant morbidity and mortality. Strategies to predict the impending development of this disorder and allow early intervention have therefore assumed importance. We routinely screen the peripheral blood of all recipients of allogeneic HSCT to detect EBV DNA by quantitative polymerase chain reaction (PCR) technology and report here how this correlates with clinical disease and management. PROCEDURE: Data on 28 successive patients who underwent HSCT at our institution were reviewed. The relationship between EBV reactivation demonstrated by quantitative PCR and development of post transplant lymphoproliferative disease (PTLD) was determined. RESULTS: EBV reactivation occurred in 68% of patients, however only 7% developed clinical PTLD. Patients with high level reactivation (n = 9) had more frequent episodes of reactivation and all patients who progressed to overt PTLD were found in this group. In contrast none of those patients with low level reactivation (n = 10) or persistently negative results (n = 9) showed any signs of clinical disease. Anti-CD20 monoclonal antibody (Rituximab) therapy was instigated in both cases of proven PTLD and three cases of high level reactivation with successful outcomes. Response to treatment was associated with a prompt decline in viral copy number. CONCLUSIONS: Our results indicate that EBV reactivation is a common occurrence in the paediatric allogeneic transplant setting and that only a proportion of patients will progress to PTLD. Frequent monitoring may help to predict those at highest risk and guide intervention.

A cross-linker-sensitive myeloid leukemia cell line from a 2-year-old boy with severe Fanconi anemia and biallelic FANCD1/BRCA2 mutations.

Fanconi anemia (FA) is a rare autosomal recessive disorder characterized by congenital and developmental abnormalities, hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC), and strong predisposition to acute myeloid leukemia (AML). In this article, we describe clinical and molecular findings in a boy with a severe FA phenotype who developed AML by the age of 2. Although he lacked a strong family history of cancer, he was subsequently shown to carry biallelic mutations in the FANCD1/BRCA2 gene. These included an IVS7 splice-site mutation, which is strongly associated with early AML in homozygous or compound heterozygous carrier status in FA-D1 patients. Myeloid leukemia cells from this patient have been maintained in culture for more than 1 year and have been designated as the SB1690CB cell line. Growth of SB1690CB is dependent on granulocyte macrophage colony stimulating factor or interleukin-3. This cell line has retained its MMC sensitivity and has undergone further spontaneous changes in the spectrum of cytogenetic aberrations compared with the primary leukemia. This is the second AML cell line derived from an FA-D1 patient and the first proof that malignant clones arising in FA patients can retain inherited MMC sensitivity. As FA-derived malignancies are normally not very responsive to treatment, this implies there are important mechanisms of acquiring correction of the cellular FA phenotype that would explain the poor chemoresponsiveness observed in FA-associated malignancies and might also play a role in the initiation and progression of cancer in the general population.

Bone mineral density in childhood survivors of acute lymphoblastic leukemia treated without cranial irradiation.

Adult survivors of childhood acute lymphoblastic leukemia (ALL) whose treatment included cranial irradiation (XRT) have reduced bone mineral density (BMD). Fifty-three survivors of ALL (aged 6-17 yr; 22 males and 31 females), who had completed their treatment without XRT, at least 1 yr previously, and 187 (5-19 yr; 86 males and 101 females) healthy controls were examined with dual energy x-ray absorptiometry of the total body and L1-L4 vertebrae and peripheral quantitative computer tomography at the distal and midradial sites. The total body and lumbar spine BMDs did not differ between the ALL survivors and controls. Distal radial trabecular BMD (difference, -0.080 mg/cm(3); 95% confidence interval, -0.139 to -0.020; P = 0.009), but not total BMD (difference, -0.006 mg/cm(3); confidence interval, -0.051 to 0.039; P = 0.80), was lower in ALL survivors compared with controls. At the midradial site, both endosteal (11% larger; P = 0.0001) and periosteal (4% larger; P = 0.001) circumferences were greater, and cortical thickness was thinner by 6% (P = 0.006) in the ALL subjects, leading to an increase in the axial moment of inertia in the ALL subjects (difference, 13%; P = 0.008). In conclusion, BMD, except at the radius, is normal in childhood survivors of ALL treated without XRT. At the midradial site, we speculate that ALL or its treatment resulted in endosteal bone loss and cortical bone thinning, but the axial moment of inertia and, hence, strength was maintained as a result of bone gain at the periosteal surface.

Combined glucose-6-phosphate dehydrogenase and glucosephosphate isomerase deficiency can alter clinical outcome.

Glucosephosphate isomerase (GPI) deficiency in humans is an autosomal recessive disorder, which results in nonspherocytic hemolytic anemia of variable clinical expression. A 4-year-old female with severe congenital hemolytic anemia had low red cell GPI activity of 15.5 IU/g Hb (50% of normal mean) indicating GPI deficiency. Subsequent DNA sequence analysis revealed a novel homozygous 921C to G mutation in the GPI gene sequence, predicting a Phe307 to Leu replacement. Strikingly, the red cell GPI activity in this patient was higher than that found in a second patient expressing the same GPI variant, with a more severe clinical phenotype. We propose that the hemolysis in the first patient may be modified by an accompanying deficiency of glucose-6-phosphate dehydrogenase (G6PD). The proband's red cell G6PD activity was reduced at 4.5 IU/g Hb (50% of normal mean) and molecular studies revealed heterozygosity for the G6PD Viangchan mutation and a skewed pattern of X-chromosome inactivation, producing almost exclusive expression of the mutated allele. The G6PD Viangchan variant is characterised by severe enzyme deficiency, but not chronic hemolysis. This study suggests that the metabolic consequences of a combined deficiency of GPI and G6PD might be responsible for a different clinical outcome than predicted for either defect in isolation.

Constitutional sequence variation in the Fanconi anaemia group C (FANCC) gene in childhood acute myeloid leukaemia.

The extent to which genetic susceptibility contributes to the causation of childhood acute myeloid leukaemia (AML) is not known. The inherited bone marrow failure disorder Fanconi anaemia (FA) carries a substantially increased risk of AML, raising the possibility that constitutional variation in the FA (FANC) genes is involved in the aetiology of childhood AML. We have screened genomic DNA extracted from remission blood samples of 97 children with sporadic AML and 91 children with sporadic acute lymphoblastic leukaemia (ALL), together with 104 cord blood DNA samples from newborn children, for variations in the Fanconi anaemia group C (FANCC) gene. We found no evidence of known FANCC pathogenic mutations in children with AML, ALL or in the cord blood samples. However, we detected 12 different FANCC sequence variants, of which five were novel to this study. Among six FANCC variants leading to amino-acid substitutions, one (S26F) was present at a fourfold greater frequency in children with AML than in the cord blood samples (odds ratio: 4.09, P = 0.047; 95% confidence interval 1.08-15.54). Our results thus do not exclude the possibility that this polymorphic variant contributes to the risk of a small proportion of childhood AML.

Related umbilical cord blood transplantation in patients with thalassemia and sickle cell disease.

Allogeneic bone marrow transplantation (BMT) from HLA-identical siblings is an accepted treatment for both thalassemia and sickle cell disease (SCD). However, it is associated with decided risk of both transplant-related mortality (TRM) and chronic graft-versus-host disease (GVHD). We analyzed 44 patients (median age, 5 years; range, 1-20 years) given an allogeneic related cord blood transplant for either thalassemia (n = 33) or SCD (n = 11). Thirty children were given cyclosporin A (CsA) alone as GVHD prophylaxis, 10 received CsA and methotrexate (MTX), and 4 patients received other combinations of immunosuppressive drugs. The median number of nucleated cells infused was 4.0 x 10(7)/kg (range, 1.2-10 x 10(7)/kg). No patient died and 36 of 44 children remain free of disease, with a median follow-up of 24 months (range, 4-76 months). Only one patient with SCD did not have sustained donor engraftment as compared with 7 of the 33 patients with thalassemia. Three of these 8 patients had sustained donor engraftment after BMT from the same donor. Four patients experienced grade 2 acute GVHD; only 2 of the 36 patients at risk developed limited chronic GVHD. The 2-year probability of event-free survival is 79% and 90% for patients with thalassemia and SCD, respectively. Use of MTX for GVHD prophylaxis was associated with a greater risk of treatment failure. Related CBT for hemoglobinopathies offers a good probability of success and is associated with a low risk of GVHD. Optimization of transplantation strategies could further improve these results.

Cultured autografting for juvenile myelomonocytic leukaemia.

A case of juvenile myelomonocytic leukaemia (JMML) associated with a chromosomal translocation (1;5) is described. Initial cytoreductive therapy failed to control the disease. In the absence of a matched family or unrelated donor, a Dexter-type long-term bone marrow culture (LTBMC) was established. The LTBMC showed preferential growth of normal stem cells over the abnormal clone, allowing a cultured autologous stem cell transplantation to be performed. Despite detection of the t(1;5) from 5 months to 7 years following cultured autograft, the patient remained in haematological remission. Currently the patient is alive and well at 10 years in full cytogenetic remission.