Mark Layton

Role of receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin and macrophage protein 1-alpha (MIP-1a) in monoclonal gammopathy of undetermined significance (MGUS)

The aim of this study was to evaluate the role of markers of bone remodelling, and osteoclast activation/function in patients with monoclonal gammopathy of undetermined significance (MGUS). We have measured serum levels of soluble RANKL (sRANKL), osteoprotegerin (OPG), macrophage inflammatory protein‐1alpha (MIP‐1α), markers of bone resorption [N‐telopeptide of collagen type‐I (NTX), and tartrate‐resistant acid phosphatase isoform‐5b (TRACP‐5b)] and bone formation [bone‐alkaline phosphatase (bALP)] in 40 MGUS patients. These parameters were compared with those of 42 newly diagnosed myeloma patients, and 45 healthy, gender‐ and age‐matched controls. MGUS patients had elevated levels of NTX, sRANKL, and sRANKL/OPG ratio compared with controls (P < 0·0001). Furthermore, TRACP‐5b, MIP‐1α and NTX were decreased in patients with MGUS compared with myeloma patients (P < 0·001), while OPG and bALP were increased (P < 0·001). Serum levels of MIP‐1α, as well as TRACP‐5b, and sRANKL/OPG ratio were reduced, while bALP was increased in MGUS patients, even when compared with myeloma patients who had stage I/II disease. These results demonstrate that increased osteoclastogenesis leading to increased bone resorption is present in MGUS but seems to be compensated for by normal bone formation, which is absent in MM. Furthermore MIP‐1α, bALP, and sRANKL/OPG may be useful tools for distinguishing between cases of MGUS and early myeloma.

In vivo evidence for apoptosis in the bone marrow in systemic lupus erythematosus

An increase in leucocyte apoptosis and impaired clearance of apoptotic cells has been observed in patients with systemic lupus erythematosus (SLE). Apoptotic cells are likely to be a key source of autoantigens in SLE as they express many of the nuclear autoantigens (in surface blebs and apoptotic bodies) that are relevant to this disease. The clearance of apoptotic cells is usually a rapid process, such that few cells are usually seen in the extracellular environment in vivo. We report a case in which multiple apoptotic bodies were observed in the bone marrow of a patient with SLE that was complicated by an immune-mediated pancytopenia. We have subsequently examined the frequency of apoptotic cells, identified morphologically, and by caspase-3 staining in bone-marrow trephine samples taken from patients with SLE over a 10-year period of follow-up. A high proportion of bone marrows contained apoptotic debris. The novel demonstration of apoptotic bodies in vivo in patients with SLE is unusual and supports the notion that the marrow may be a target organ in the disease. Their abundance is also consistent with the hypothesis that normal clearance mechanisms are defective and/or overwhelmed in SLE.

Glycosylphosphatidylinositol-specific, CD1d-restricted T cells in paroxysmal nocturnal hemoglobinuria

The mechanism of bone marrow failure (BMF) in paroxysmal nocturnal hemoglobinuria (PNH) is not yet known. Because in PNH the biosynthesis of the glycolipid molecule glycosylphosphatidylinositol (GPI) is disrupted in hematopoietic stem and progenitor cells by a somatic mutation in the PIG-A gene, BMF might result from an autoimmune attack, whereby T cells target GPI in normal cells, whereas PIG-A mutant GPI-negative cells are spared. In a deliberate test of this hypothesis, we have demonstrated in PNH patients the presence of CD8(+) T cells reactive against antigen-presenting cells (APCs) loaded with GPI. These T cells were significantly more abundant in PNH patients than in healthy controls; their reactivity depended on CD1d expression and they increased upon coculture with CD1d-expressing, GPI-positive APCs. In GPI-specific T cells captured by CD1d dimer technology, we identified, through global T-cell receptor α (TCRα) analysis, an invariant TCRVα21 sequence, which was then found at frequencies higher than background in the TCR repertoire of 6 of 11 PNH patients. Thus, a novel, autoreactive, CD1d-restricted, GPI-specific T-cell population, enriched in an invariant TCRα chain, is expanded in PNH patients and may be responsible for BMF in PNH.

The association between tricuspid regurgitation velocity and 5‐year survival in a North West London population of patients with sickle cell disease in the United Kingdom

Raised tricuspid regurgitant velocity (TRV) occurs in approximately 30% of adults with sickle cell disease (SCD), and has been shown to be an independent risk factor for death. TRV was assessed in 164 SCD patients who were subsequently followed up for survival. Raised pulmonary pressures were defined as a TRV jet ≥2·5 m/s on echocardiography. Elevated TRV was present in 29·1% of patients and it was associated with increased age and left atrial diameter. There were 15 deaths (9·1%) over a median of 68·1 months follow up; seven patients had increased TRV, and eight patients had a TRV<2·5 m/s. Higher TRV values were associated with a greater than 4‐fold increased risk of death (Hazard Ratio: 4·48, 99% confidence interval 1·01‐19·8), although we found a lower overall mortality rate than has been reported in previous studies. TRV was not an independent risk factor for death. We have confirmed the association between raised TRV and mortality in a UK SCD population whose disease severity appears to be less than that reported in previous studies. Further prospective studies are needed to more clearly characterize which patient factors modify survival in SCD patients with raised TRV.

Erythrocytapheresis in the prevention of recurrent myocardial infarction in sickle cell disease

To the Editor: Erythrocytapheresis is an established therapy for the prevention of stroke in sickle cell disease [1]. We report its use in the prevention of recurrent acute coronary syndromes. A 50-year-old woman, with homozygous sickle cell disease presented in December 2005 with central chest pain, T wave inversion in V1–V3 and biphasic T waves in V4–V6. She was treated with aspirin, clopidogrel, and enoxaparin. Her troponin I peaked at 8.23 lg/L 12 hr later. Cardiac magnetic resonance imaging (MRI) showed subendocardial hyperenhancement in the lateral wall of the left ventricle consistent with an infarct. Coronary angiography showed no obstruction [2]. A long-term red cell exchange program was considered but deferred in the absence of evidence of recurrent myocardial infarction in sickle cell disease. Nine months later the patient presented with central chest pain of sudden onset. Electrocardiography showed new onset atrial fibrillation with T wave inversion across V1–V4. Serum troponin I was elevated at 0 19 lg/ L and rose to 4 61 lg/L 12 hr later. Cardiac MRI was unchanged compared with the previous study. Treatment with enoxaparin was commenced and electrocardioversion undertaken, successful only with amiodarone preloading. In light of the recurrence of myocardial infarction, a red cell exchange program to achieve a target hemoglobin S level of <30% was implemented. Thirty-four months after this second event, the patient is maintained on a regular red cell exchange program and remains well in sinus rhythm. We have recommended erythrocytapheresis is continued on an indefinite basis. Although regular red cell transfusions to suppress the level of hemoglobin S are well established in the primary and secondary prevention of stroke in sickle cell disease [1], they have not previously been shown to reduce the risk of recurrent myocardial infarction. We believe hematologists should be aware of the potential benefit of such an approach.

Two novel mutations in severe factor VII deficiency

We have characterized the molecular defect in two families with severe factor VII (FVII) deficiency. In family I, the proband was found to be homozygous for a novel 18 bp deletion in exon 8 (g.10896‐10913del) resulting in the in‐frame deletion of six amino acids in the serine protease domain. Molecular modelling suggests the deletion is likely to disrupt folding of the FVII molecule. The reduced FVII antigen (21 U/dl) and negligible activity (0·4 U/dl) in the patients plasma indicated that the deletion affected both the secretion/stability and function of the mutant protein. In family II, the proband was found to be a compound heterozygote for a novel missense mutation (g.7884G>A; FVII G117R) in exon 5 encoding the EGF2 domain of FVII and a nonsense mutation (g.8960C>T; FVII R152X) in exon 6. Extensive sequence comparison in a wide evolutionary context suggested that the Gly117 residue is critical for structure of FVII. The grossly reduced FVII antigen (1·1 U/dl) and activity (0·4 U/dl) plasma values indicate the mutation primarily affected the folding/secretion or stability of the protein.

Managing the difficult case of fetal anemia

Objectives. To describe a series of complex fetal anemia cases, detail the appropriate investigations and management, and review the literature. Methods. Four cases of non-red cell alloimmunization or infective cases of fetal anemia are presented. Results. Of the four cases presented, one was a neonatal death, one pregnancy was terminated, one case was diagnosed with Diamond Blackfan anemia, and one case was due to recurrent feto-maternal hemorrhages despite negative Kleihauer tests. Conclusions. Non-alloimmune causes of fetal anemia can be difficult to manage. Some cases require repeated and frequent intrauterine transfusions. The perinatal mortality and preterm delivery rates are increased, and some cases require considerable long-term treatment including regular transfusions. We present our experience of a series of non-immune fetal anemia managed in a tertiary unit, review the literature, and suggest appropriate management.

Missense mutations in the perforin (PRF1) gene as a cause of hereditary cancer predisposition.

ABSTRACT Perforin, a pore-forming toxin released from secretory granules of NK cells and CTLs, is essential for their cytotoxic activity against infected or cancerous target cells. Bi-allelic loss-of-function mutations in the perforin gene are invariably associated with a fatal immunoregulatory disorder, familial haemophagocytic lymphohistiocytosis type 2 (FHL2), in infants. More recently, it has also been recognized that partial loss of perforin function can cause disease in later life, including delayed onset FHL2 and haematological malignancies. Herein, we report a family in which a wide range of systemic inflammatory and neoplastic manifestations have occurred across three generations. We found that disease was linked to two missense perforin gene mutations (encoding A91V, R410W) that cause protein misfolding and partial loss of activity. These cases link the partial loss of perforin function with some solid tumors that are known to be controlled by the immune system, as well as haematological cancers. Our findings also demonstrate that perforin gene mutations can contribute to hereditary cancer predisposition.

New haplotype for the Glu104Asp mutation in triose-phosphate isomerase deficiency and prenatal diagnosis in a Spanish family

SummaryFirst-trimester prenatal diagnosis was undertaken by chorionic villus DNA analysis in a Spanish family with the inherited Glu104Asp triose-phosphate isomerase deficiency. The fetus was heterozygous for the mutation and therefore predicted to be clinically unaffected. To investigate the evolutionary origin of this mutation, studies were conducted on the intragenic 2262A/G polymorphism and the CD4 pentameric tandem repeat marker. A different haplotype was found to the one previously described, suggesting a different origin of the Spanish mutation.

White matter integrity and processing speed in sickle cell anemia

Objective The purpose of this retrospective cross-sectional study was to investigate whether changes in white matter integrity are related to slower processing speed in sickle cell anemia. Methods Thirty-seven patients with silent cerebral infarction, 46 patients with normal MRI, and 32 sibling controls (age range 8–37 years) underwent cognitive assessment using the Wechsler scales and 3-tesla MRI. Tract-based spatial statistics analyses of diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) parameters were performed. Results Processing speed index (PSI) was lower in patients than controls by 9.34 points (95% confidence interval: 4.635–14.855, p = 0.0003). Full Scale IQ was lower by 4.14 scaled points (95% confidence interval: −1.066 to 9.551, p = 0.1), but this difference was abolished when PSI was included as a covariate (p = 0.18). There were no differences in cognition between patients with and without silent cerebral infarction, and both groups had lower PSI than controls (both p < 0.001). In patients, arterial oxygen content, socioeconomic status, age, and male sex were identified as predictors of PSI, and correlations were found between PSI and DTI scalars (fractional anisotropy r = 0.614, p < 0.00001; r = −0.457, p < 0.00001; mean diffusivity r = −0.341, p = 0.0016; radial diffusivity r = −0.457, p < 0.00001) and NODDI parameters (intracellular volume fraction r = 0.364, p = 0.0007) in widespread regions. Conclusion Our results extend previous reports of impairment that is independent of presence of infarction and may worsen with age. We identify processing speed as a vulnerable domain, with deficits potentially mediating difficulties across other domains, and provide evidence that reduced processing speed is related to the integrity of normal-appearing white matter using microstructure parameters from DTI and NODDI.