Melanie Cotter

A large kindred with X-linked neutropenia with an I294T mutation of the Wiskott-Aldrich syndrome gene

X‐linked neutropenia (XLN, OMIM #300299) is a rare form of severe congenital neutropenia. It was originally described in a three‐generation family with five affected members that had an L270P mutation in the GTP‐ase binding domain (GBD) of the Wiskott‐Aldrich syndrome protein (WASP) [ Devriendt et al (2001) Nature Genetics, Vol. 27, 313–317 ]. Here, we report and describe a large three‐generation family with XLN, with 10 affected males and eight female carriers. A c.882T>C mutation was identified in the WAS gene, resulting in an I294T mutation. The infectious course is variable and mild in view of the profound neutropenia. In addition to the original description, low‐normal IgA levels, low to low‐normal platelet counts and reduced natural killer (NK)‐cell counts also appear as consistent XLN features. However, inverted CD4/CD8 ratios were not found in this family, nor were cases identified with myelodysplastic syndrome or acute myeloid leukaemia. Female carriers exhibited a variable attenuated phenotype. Like L270P WASP, I294T WASP is constitutively active towards actin polymerization. In conclusion, this largest XLN kindred identified to date provides new independent genetic evidence that mutations disrupting the auto‐inhibitory GBD of WASP are the cause of XLN. Reduced NK cells, low to low normal platelet counts and low to low‐normal IgA levels are also features of XLN.

Successful use of gemtuzumab ozogamicin in a child with relapsed cd33‐positive acute lymphoblastic leukaemia

Zipursky (2003) elegantly reviewed the transient myeloproliferative disorder (TMD), also known as transient abnormal myelopoiesis, in infants with Down’s syndrome, and provided evidence that this might, in fact, be a transient leukaemia. The disorder may present with life-threatening complications, but if the infants can be helped over the acute phase, most patients experience a spontaneous regression. However, up to 30% of these infants subsequently develop acute megakaryoblastic leukaemia (AMKL). Two recent studies showed that mutations of the GATA1 gene, found initially in AMKL in patients with Down’s syndrome (Wechsler et al, 2002), also occurred in TMD. Mundschau et al (2003) found that all of seven TMD samples examined showed GATA1 mutations. Whether any of these patients progressed to AMKL was not discussed. Hitzler et al (2003), in addition to finding GATA1 mutations in TMD, also demonstrated an identical GATA1 mutation in sequential samples collected from a patient with TMD and subsequent AMKL. These results provide a causal link between TMD and AMKL. What the results do not explain is why the TMD clone subsequently disappears in many patients, but progresses to AMKL in others. A patient that we described 10 years ago (Kwong et al, 1993), who Zipursky (2003) did not discuss, may contain some relevant information. This was a newborn male infant who presented soon after birth with hepatosplenomegaly, pulmonary infiltration and leucocytosis (88Æ9 · 10 ⁄ l, 48% blasts). The blasts were positive for CD34 and CD33, the megakaryocytic markers CD41, CD42b and CD61, and Tcell markers CD3 and CD7. Dual-colour flow cytometric analysis of surface antigens and DNA ploidy showed the presence of a predominant 2N and a minor 4N blast population on presentation (Fig 1). However, during the first week, there was a progressive increase in circulating blasts that were 4N, 6N and even 8N, suggesting a polyploidization process similar to that in megakaryocytic maturation. These polyploid blasts subsequently dwindled in number, which was accompanied by a concomitant fall in blast count. By the end of the first week, the blast count had dropped to about 1%. The patient was managed conservatively, and a d 30 marrow biopsy showed normal morphological features. Cytogenetic analysis of the blasts showed trisomy 21 only. Interestingly, the blasts showed

Successful treatment with rituximab and mycophenolate mofetil of refractory autoimmune hemolytic anemia post‐hematopoietic stem cell transplant for dyskeratosis congenita due to TINF2 mutation

AIHA following allogeneic HSCT is appearing more frequently in the literature. It occurs as a result of donor cell‐derived antibodies targeting donor red cell antigens. Little guidance exists on the management of such patients, particularly in the pediatric setting. First‐line conventional treatment is corticosteroids and/or immunoglobulin therapy with monoclonal antibody therapy reserved for treatment failure. We report our experience of a child refractory to immunoglobulin and steroid therapy who required several infusions of rituximab and immunomodulatory therapy to obtain a clinically significant response.

Successful treatment of acute Epstein–Barr virus infection associated with X‐linked lymphoproliferative disorder with rituximab

To the Editor: We describe the case of an 8 month old male who presented with a short history of swinging fevers, rash, generalized lymphadenopathy, hepatosplenomegaly with an associated hemophagocytic syndrome secondary to acute Epstein–Barr virus (EBV) infection. Quantitative PCR revealed a high EBV viral load of 2.1 10 copies/ml. Immunological testing of peripheral blood lymphocytes revealed absent SLAM-associated protein (SAP) [1]. Genetic analysis subsequently revealed a point mutation at position 163 (c.163C>T) in exon 2 of the SH2D1A gene, confirming the diagnosis of X-linked lymphoproliferative disorder (XLP) [1]. Immunomodulatory treatment with methylprednisolone (5 mg/ kg/day) and intravenous immunoglobulin (1 g/kg/day for two doses followed by 2 g/kg weekly for four doses) together with targeted B-cell directed therapy with rituximab (375 mg/m weekly for four doses) was administered. The patient had a rapid symptomatic response over the first week of treatment, becoming apyrexial with disappearance of rash and regression of hepatosplenomegaly. Over the same period his blood counts normalized as did his hepatic transaminitis (Fig. 1). Serial measurements of EBVDNA levels showed a striking decrease in viral load, ultimately to levels below the lower limit of detection of the assay (Fig. 1). An expected reduction in B-cell numbers following rituximab treatment was also seen (data not shown). He was discharged from hospital on a tapering dose of corticosteroids. He has now

Retinal vasculopathy in autosomal dominant dyskeratosis congenita due to TINF2 mutation

A four-year-old boy with autosomal dominant dyskeratosis congenita (DC) and bone marrow failure (BMF) underwent routine ophthalmological assessment prior to matched unrelated haematopoietic stem cell transplantation (HSCT). Visual acuity was reduced in both eyes. Fundus examination showed a vitreous haemorrhage in the right eye and the left eye displayed a large circinate exudate encroaching on the macula. In the left temporal retina, areas of retinal haemorrhage and extensive areas of arterial occlusion and vascular sheathing were seen (top left). Flourescein angiography of the left eye confirmed extensive and profound vascular shut down in the temporal retina and choroid. At the junction of perfused and nonperfused retina there were numerous arteriovenous shunts (top right). Bilateral laser photocoagulation was directed to the areas of retinal nonperfusion. The patient’s father had undergone a sibling-HSCT at the age of 13 years for BMF secondary to phenotypic DC that had been diagnosed 2 years previously. The patient presented at age 3 years with BMF. Telomere length, assessed by flow fluorescence in situ hybridization, showed both the patient and his two-yearold sister to be less than the first percentile for age. Molecular analysis showed both of them to be heterozygous for a TINF2 mutation: c.844C>T (amino acid substitution: p.Arg282Cys). Interestingly, TINF2 was not considered a candidate gene in the boy or his sister as a previous screen by denaturing high performance liquid chromatography analysis on their affected father had not revealed any abnormality. However, reinvestigating this same sample from the father, which had come from a buccal mouthwash (post-HSCT), there was a small proportion (10%) of the mutant allele visible on the sequencing trace, strongly suggesting that he is a mosaic for a TINF2mutation that causes DC and this mutation has been inherited by both children. TINF2, the second most commonly mutated gene in DC encodes TINF2 (also known as TIN2), a member of the telomere-associated shelterin complex, which plays integral roles in the structure and function of telomeres. TINF2 mutations are usually associated with extremely short telemeres, earlier onset of disease and bone marrow failure that usually occurs prior to manifestation of any signs of the classic triad of DC. All reported mutations, most of which arise de novo, are heterozygous. Retinal abnormalities are seen in about 20% of patients with DC. In Revesz syndrome (Mendelian Inheritance in Man #268130), a severe DC variant caused by TINF2 mutations, bilateral exudative retinopathy is a defining feature along with intrauterine growth retardation, intracranial calcification and cerebellar hypoplasia. The patient is 100% donor chimera 9 months after HSCT, continues to be neurologically normal and has developed finger and toe nail dystrophy (bottom left and right) some 7 years earlier than his father did. This phenotypic variability (BMF onset and nail dystrophy) between father and son most likely reflects the father’s TINF2 mosaicism.

Increased bone marrow angiogenesis in children with severe chronic neutropenia treated with granulocyte colony-stimulating factor.

Severe chronic neutropenia (SCN) is a heterogeneous group of conditions characterized by chronically low neutrophil counts and recurrent infections. Granulocyte colony-stimulating factor (G-CSF) is the mainstay of treatment, and evidence exists that G-CSF may promote angiogenesis. To evaluate the effects of G-CSF on angiogenesis in children with SCN, the authors assessed microvessel density in bone marrow biopsies from nine children with SCN before starting G-CSF treatment and while receiving G-CSF. In all patients, microvessel density was greater in the on-treatment biopsy. Increased angiogenesis may result from a direct effect of G-CSF on endothelial cells or may be an indirect effect from increased neutrophils.

Plasmacytoma occurring in scar tissue.

A 76-year-old man with a 14-year history of monoclonal gammopathy of undetermined significance (MGUS, IgG lambda) suffered a traumatic fracture of his right humerus, requiring internal fixation with an intramedullary nail. Three months later, several rapidly growing tumours developed at the sites of the recent surgery (left and centre). Fine needle aspirate of the tumours demonstrated that these were plasmacytomas (IgG lambda). Bone marrow aspirate and biopsy demonstrated 60% infiltration with plasma cells, indicating transformation to multiple myeloma. The patient was treated using local radiotherapy, with resolution of the lesions. However, within 1 month, further similar lesions developed in a sterniotomy scar where the patient had undergone cardiac surgery 14 years previously (right). Despite further treatment with local radiotherapy, intravenous pamidronate, and oral melphalan and prednisolone, the patient’s general medical condition deteriorated and he died. The occurrence of malignant tumours in scar tissue is a well-recognized phenomenon. The majority of cases describe the development of squamous cell carcinoma in burn scars or in chronic wounds (Marjolin’s ulcer), or tumour cell ‘seeding’ along the needle track of a biopsy site. To our knowledge, plasmacytoma with a predilection for scar tissue has not been previously described.