Biological, clinical features and modelling of heterozygous variants of glycoprotein Ib platelet subunit alpha (GP1BA) and glycoprotein Ib platelet subunit beta (GP1BB) genes responsible for constitutional thrombocytopenia.

Constitutional thrombocytopenias are rare disorders, often difficult to discriminate from acquired thrombocytopenias. More than 80 genes have been described as being at the origin of these diseases. Among them, several variants of the glycoprotein Ib platelet subunit alpha (GP1BA) and glycoprotein Ib platelet subunit beta (GP1BB) genes, coding for the GpIb-IX-V glycoprotein complex, have been reported in the literature. The study reported here aimed at describing newly identified monoallelic anomalies affecting the GP1BA and GP1BB genes on a clinical, biological and molecular level. In a cohort of nine patients with macrothrombocytopenia, eight heterozygous variants of the GP1BA or GP1BB genes were identified. Five of them had never been described in the heterozygous state. Computer modelling disclosed structure/function relationships of these five variants.

Robust Detection of Somatic Mosaicism and Repeat Interruptions by Long-Read Targeted Sequencing in Myotonic Dystrophy Type 1.

Myotonic dystrophy type 1 (DM1) is the most complex and variable trinucleotide repeat disorder caused by an unstable CTG repeat expansion, reaching up to 4000 CTG in the most severe cases. The genetic and clinical variability of DM1 depend on the sex and age of the transmitting parent, but also on the CTG repeat number, presence of repeat interruptions and/or on the degree of somatic instability. Currently, it is difficult to simultaneously and accurately determine these contributing factors in DM1 patients due to the limitations of gold standard methods used in molecular diagnostics and research laboratories. Our study showed the efficiency of the latest PacBio long-read sequencing technology to sequence large CTG trinucleotides, detect multiple and single repeat interruptions and estimate the levels of somatic mosaicism in DM1 patients carrying complex CTG repeat expansions inaccessible to most methods. Using this innovative approach, we revealed the existence of de novo CCG interruptions associated with CTG stabilization/contraction across generations in a new DM1 family. We also demonstrated that our method is suitable to sequence the DM1 locus and measure somatic mosaicism in DM1 families carrying more than 1000 pure CTG repeats. Better characterization of expanded alleles in DM1 patients can significantly improve prognosis and genetic counseling, not only in DM1 but also for other tandem DNA repeat disorders.

Identification of new F8 deep intronic variations in patients with haemophilia A.

INTRODUCTION: With current molecular diagnosis, about 1 to 5% of haemophilia A (HA) patients remain genetically unresolved. In these cases, deep intronic variation or structural variation disrupting the F8 gene could be causal. AIM: To identify the causal variation in four genetically unresolved mild-to-severe HA patients using an F8 mRNA analysis approach. METHODS: Ectopic F8 mRNA analysis was performed in four unrelated HA patients. An in vitro minigene assay was performed in order to confirm the deleterious splicing impact of each variation identified. RESULTS: In all probands, mRNA analysis revealed an aberrant splicing pattern, and sequencing of the corresponding intronic region found a deep intronic substitution. Two of these were new variations: c.2113+601G>A and c.1443+602A>G, while the c.143+1567A>G, found in two patients, has previously been reported. The c.1443+602A>G and the c.143+1567A>G variants both led to the creation of a de novo acceptor or donor splice site, respectively. Moreover, the c.143+1567A>G was found in 3/6 patients with genetically unresolved moderate HA registered in our laboratory. Haplotype analysis performed in all patients carrying the c.143+1567A>G variation suggests that this variation could be a recurrent variation. The c.2113+601G>A led to the exonization of a 122-bp antisense AluY element by increasing the strength of a pre-existing cryptic 5' splice site. For each point variation, in vitro splicing analysis confirmed its deleterious impact on splicing of the F8 transcript. CONCLUSION: We identified three deep intronic variations, leading to an aberrant mRNA splicing process as HA causing variation.

Relevance of platelet desialylation and thrombocytopenia in type 2B von Willebrand disease: preclinical and clinical evidence.

Patients with type 2B von Willebrand disease (vWD) (caused by gain-of-function mutations in the gene coding for von Willebrand factor) display bleeding to a variable extent and, in some cases, thrombocytopenia. There are several underlying causes of thrombocytopenia in type 2B vWD. It was recently suggested that desialylation-mediated platelet clearance leads to thrombocytopenia in this disease. However, this hypothesis has not been tested in vivo The relationship between platelet desialylation and the platelet count was probed in 36 patients with type 2B von Willebrand disease (p.R1306Q, p.R1341Q, and p.V1316M mutations) and in a mouse model carrying the severe p.V1316M mutation (the 2B mouse). We observed abnormally high elevated levels of platelet desialylation in both patients with the p.V1316M mutation and the 2B mice. In vitro, we demonstrated that 2B p.V1316M/von Willebrand factor induced more desialylation of normal platelets than wild-type von Willebrand factor did. Furthermore, we found that N-glycans were desialylated and we identified αIIb and ß3 as desialylation targets. Treatment of 2B mice with sialidase inhibitors (which correct platelet desialylation) was not associated with the recovery of a normal platelet count. Lastly, we demonstrated that a critical platelet desialylation threshold (not achieved in either 2B patients or 2B mice) was required to induce thrombocytopenia in vivo In conclusion, in type 2B vWD, platelet desialylation has a minor role and is not sufficient to mediate thrombocytopenia.

Risk estimation of uniparental disomy of chromosome 14 or 15 in a fetus with a parent carrying a non-homologous Robertsonian translocation. Should we still perform prenatal diagnosis?

OBJECTIVE: Uniparental disomy (UPD) testing is currently recommended during pregnancy in fetuses carrying a balanced Robertsonian translocation (ROB) involving chromosome 14 or 15, both chromosomes containing imprinted genes. The overall risk that such a fetus presents a UPD has been previously estimated to be around ~0.6-0.8%. However, because UPD are rare events and this estimate has been calculated from a number of studies of limited size, we have reevaluated the risk of UPD in fetuses for whom one of the parents was known to carry a nonhomologous ROB (NHROB). METHOD: We focused our multicentric study on NHROB involving chromosome 14 and/or 15. A total of 1747 UPD testing were performed in fetuses during pregnancy for the presence of UPD(14) and/or UPD(15). RESULT: All fetuses were negative except one with a UPD(14) associated with a maternally inherited rob(13;14). CONCLUSION: Considering these data, the risk of UPD following prenatal diagnosis of an inherited ROB involving chromosome 14 and/or 15 could be estimated to be around 0.06%, far less than the previous estimation. Importantly, the risk of miscarriage following an invasive prenatal sampling is higher than the risk of UPD. Therefore, we do not recommend prenatal testing for UPD for these pregnancies and parents should be reassured.

Inherited Thrombotic Thrombocytopenic Purpura Revealed by Recurrent Strokes in a Male Adult: Case Report and Literature Review.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy related to a severe deficiency of ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13). In this article, we describe the first case of a young male adult suffering from a hereditary TTP revealed by recurrent strokes, relapsing despite antiplatelet and anticoagulant therapy. Because of the persistent moderate thrombocytopenia, plasmatic ADAMTS13 activity was investigated and was found lower than 5% in the absence of anti-ADAMTS13 IgG. Direct sequencing of ADAMTS13 gene led to the diagnosis of Upschaw-Schulman syndrome (USS). Inherited TTP or USS is a rare autosomal recessive inherited disease leading to a severe deficiency of ADAMTS13 mostly beginning in childhood or in young female adult during pregnancy. Our patient was treated with fresh frozen plasma every 2 weeks. One year after diagnosis, he was free of neurological symptoms. Around 12 cases of inherited TTP diagnosed in adults (outside pregnancy) are described in literature. Only 4 of them exhibited a stroke. This case is the first late onset genetic TTP revealed by recurrent strokes, moderate thrombocytopenia without anemia.

Differential diagnosis of neonatal alloimmune thrombocytopenia: Type 2B von Willebrand disease.

At birth, severe thrombocytopenia without context of infection should mainly suggest neonatal alloimmune thrombocytopenia (NAIT), especially in case of a platelet count below 20 GL-1. We report two cases of severe neonatal thrombocytopenia, first suspected as being NAIT. Both had a platelet count below 20 GL-1 with platelet clumps. The absence of alloantibodies and failure of platelet transfusion and intravenous immunoglobulins to improve the platelet count led to question the diagnosis and to evoke inherited bleeding disorders. Measurements of Von Willebrand factor (VWF) levels showed a marked reduction of VWF:RCo and a normal VWF:Ag, suggesting a type 2B Von Willebrand disease (VWD2B). Ristocetin-induced platelet aggregation could not be performed because of the very low platelet count. In the first case, after sequencing VWF exon 28, a heterozygous p.Leu1460Pro mutation was found consistent with VWD2B. In the second case, the genetic analysis of VWF exon 28 identified a homozygous mutation: p.Pro1337Leu confirming type VWD2B and also the p.Arg854Gln homozygous mutation in exon 20 confirming type 2N (ratio FVIII/VWF:Ag <0.5). The two cases underline that, even if NAIT remains the most common diagnosis in severe neonatal thrombocytopenia, it should be challenged in the absence of documented incompatibility, chronic evolution, or treatment failure. Diagnosis of VWD2B should be considered in early thrombocytopenia, even without familial history. In the cases presented, genotyping confirmed the subtype of VWD and helped to guide the therapeutic management of bleeding episodes.

Mutations in the A3 domain of von Willebrand factor inducing combined qualitative and quantitative defects in the protein.

Two unrelated families were recruited in the French Reference Center for von Willebrand Disease with moderate bleeding symptoms associated with low von Willebrand factor (VWF) antigen levels, decreased collagen binding assay, and no or partial response to desmopressin. Genetic analysis showed the presence of heterozygous mutations in the A3 domain away from the collagen-binding surface: 1 never reported previously (p.L1696R) and another (p.P1824H) described in a Spanish family. The mutations were reproduced by site-directed mutagenesis and mutant VWF was expressed in different expression systems, COS-7 cells, baby hamster kidney cells, and in VWF-deficient mice through hydrodynamic injection. p.L1696R and p.P1824H were associated with very low expression levels both in vitro and in vivo, with intracellular retention for p.P1824H. Both homozygous mutants displayed decreased binding to collagen types I and III but also decreased binding to platelet glycoproteins Ib and IIbIIIa. Co-transfections with wild-type VWF partially corrected these defects, except that collagen binding remained abnormal. The in vivo thrombosis response was severely reduced for both heterozygous mutants. In conclusion, we report 2 VWF A3 domain mutations that induce a combined qualitative and quantitative defect.

Incidence of obstetrical thrombotic thrombocytopenic purpura in a retrospective study within thrombocytopenic pregnant women. A difficult diagnosis and a treatable disease.

BACKGROUND: Thrombotic thrombocytopenic Purpura (TTP) defined as ADAMTS-13 (A Disintegrin And Metalloprotease with ThromboSpondin type 1 domain 13) activity <10 % is a rare aetiology of thrombocytopenia during pregnancy, although the precise incidence is unknown. During pregnancy, the diagnosis of TTP is crucial as it has high feto-maternal morbidity-mortality and requires urgent plasma exchange. The purpose of this study was to assess the incidence of TTP retrospectively and to describe case presentations and follow-up. METHODS: A monocentric retrospective study (2008-2009) was conducted among pregnant women followed in a tertiary care obstetrical unit who experienced at least one episode of severe thrombocytopenia (platelets ≤75 G/L) during 2008 and 2009. In cases of uncertain aetiology of thrombocytopenia, ADAMTS-13 activity was assessed by the full length technique. RESULTS: Among 8,908 deliveries over the 2 year period, 79 women had a platelet count nadir ≤75 G/L. Eighteen had a known aetiology of thrombocytopenia and 11 were lost to follow-up. Among 50 remaining patients, ADAMTS-13 activity was undetectable (<5 %) in 4, consistent with the diagnosis of TTP. Platelet count spontaneously normalized in 3 patients after delivery. None presented focal cerebral involvement. Three of the four, who were primipara patients, had a sustained severe deficiency in the absence of anti-ADAMTS-13 antibodies, and ADAMTS-13 gene sequencing indicated a constitutive deficiency. The fourth, a multipara patient, had an acquired, auto-immune TTP. Placental pathology in the three primipara patients showed severe and non-specific ischemic lesions. Two patients lost their babies shortly after birth. In subsequent pregnancies in these two patients, prophylactic plasma infusion initiated early with increasing volume throughout pregnancy prevented TTP relapse, improved placental pathology, and led to normal delivery. CONCLUSIONS: The prevalence of TTP among thrombocytopenic pregnant women is high, up to 5 % in a tertiary unit. Platelet count normalization after delivery does not eliminate TTP. Clinicians should be aware of TTP during pregnancy, and, even if assessed retrospectively, ADAMTS-13 assessment is of particular importance for identifying patients with congenital TTP. In these patients, preventive plasma infusion and/or exchange can dramatically improve foetal prognosis, resulting in successful childbirth.

Unexpected frequency of Upshaw-Schulman syndrome in pregnancy-onset thrombotic thrombocytopenic purpura.

Pregnancy may be complicated by a rare but life-threatening disease called thrombotic thrombocytopenic purpura (TTP). Most cases of TTP are due to an acquired autoimmune or hereditary (Upshaw-Schulman syndrome [USS]) severe deficiency of a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13 (ADAMTS13). In the present study, we performed a cross-sectional analysis of the national registry of the French Reference Center for Thrombotic Microangiopathies from 2000-2010 to identify all women who were pregnant at their initial TTP presentation. Among 592 adulthood-onset TTP patients with a severe ADAMTS13 deficiency, 42 patients with a pregnancy-onset TTP were included. Surprisingly, the proportion of USS patients (n = 10 of 42 patients [24%]; confidence interval, 13%-39%) with pregnancy-onset TTP was much higher than that in adulthood-onset TTP in general (less than 5%) and was mostly related to a cluster of ADAMTS13 variants. In the present study, subsequent pregnancies in USS patients not given prophylaxis were associated with very high TTP relapse and abortion rates, whereas prophylactic plasmatherapy was beneficial for both the mother and the baby. Pregnancy-onset TTP defines a specific subgroup of patients with a strong genetic background. This study was registered at www.clinicaltrials.gov as number NCT00426686 and at the Health Authority, French Ministry of Health, as number P051064.

CFTR p.Arg117His associated with CBAVD and other CFTR-related disorders.

BACKGROUND: The high frequency of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene mutation p.Arg117His in patients with congenital bilateral absence of the vas deferens (CBAVD) and in newborns screened for CF has created a dilemma. METHODS: Phenotypic and genotypic data were retrospectively collected in 179 non-newborn French individuals carrying p.Arg117His and a second CFTR mutation referred for symptoms or family history, by all French molecular genetics laboratories, referring physicians, CF care centres and infertility clinics. RESULTS: 97% of the patients had the intronic T7 normal variant in cis with p.Arg117His. 89% patients were male, with CBAVD being the reason for referral in 76%. In 166/179 patients with available detailed clinical features, final diagnoses were: four late-onset marked pulmonary disease, 83 isolated CBAVD, 67 other CFTR-related phenotypes, including 44 CBAVD with pulmonary and/or pancreatic symptoms and 12 asymptomatic cases. Respiratory symptoms were observed in 30% of the patients, but the overall phenotype was mild. No correlation was observed between sweat chloride concentrations and disease severity. Five couples at risk of CF offspring were identified and four benefited from prenatal or preimplantation genetic diagnoses (PND or PGD). Eight children were born, including four who were compound heterozygous for p.Arg117His and one with a severe CF mutation. CONCLUSIONS: Patients with CBAVD carrying p.Arg117His and a severe CF mutation should benefit from a clinical evaluation and follow-up. Depending on the CBAVD patients' genotype, a CFTR analysis should be considered in their partners in order to identify CF carrier couples and offer PND or PGD.

Management and follow-up of pregnancy-onset thrombotic thrombocytopenic purpura: the French experience.

ABSTRACT: Pregnancy-onset thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening disease of which diagnosis and management requires experienced multidisciplinary teams. The mechanisms responsible for a deficiency in the disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13 (ADAMTS13) leading to pregnancy-onset TTP may be congenital or acquired, and studying ADAMTS13 conformation could be of interest. The differential diagnosis between TTP and other pregnancy-associated thrombotic microangiopathies (TMA) is often challenging. Our retrospective multicenter study highlights the significance and the challenges associated with pregnancy-onset TTP and childbirth in terms of diagnosis, obstetric management, and follow-up aspects. Among 1174 pregnancy-onset TMA enrolled in the French Registry for TMA from 2000 to 2020, we identified 108 pregnancy-onset TTP: 52 immune-mediated TTP (iTTP, 48.1%), 27 acquired TTP of unidentified mechanism (uTTP, 25%), and 29 congenital TTP (cTTP, 26.9%). Data show that maternal outcome is good (survival rate: 95%) and fetal outcome is linked to the gestational age at the onset of the disease (survival rate: 75.5%). Three distinct entities with different natural histories emerged: pregnancy-onset iTTP appears similar to idiopathic iTTP, with an open ADAMTS13 conformation, and is marked by a relapse risk independent of subsequent pregnancies; pregnancy-onset uTTP appears to have a different pathophysiology with an unexpected open ADAMTS13 conformation and a very low relapse risk independent of subsequent pregnancies; finally, pregnancy-onset cTTP is characterized by the necessity of pregnancy as a systematic and specific trigger and a need for prophylactic plasmatherapy for subsequent pregnancies. This trial was registered at www.clinicaltrials.gov as #NCT00426686, and at the Health Authority and the French Ministry of Health (P051064/PHRC AOM05012).

Genotype-Dependent Response to Desmopressin in Hemophilia A and Proposal of a Predictive Response Score.

BACKGROUND: Desmopressin (DDAVP) is used in patients with moderate/mild hemophilia A (PWMHs) to increase their factor VIII (FVIII) level and, if possible, normalize it. However, its effectiveness varies between individuals. The GIDEMHA study aims to investigate the influence of F8 gene variants. MATERIAL AND METHODS: The study collected the trajectory of FVIII levels from therapeutic intravenous DDAVP tests in four French hemophilia treatment centers. A pharmacological analysis was performed associated with efficacy scores according to F8 variants: absolute and relative responses, as well as new scores: absolute duration (based on duration with FVIII ≥ 0.50 IU.mL-1) and relative duration (based on half-life). RESULTS: From enrolled 439 PWMHs, 327 had a hot-spot F8 variant (with ≥5 PWMHs). For these, the median (min-max) basal and peak FVIII were 0.20 (0.02-0.040) and 0.74 (0.14-2.18) IU.mL-1 respectively, with FVIII recovery being 3.80 IU.ml-1 (1.15-14.75). The median FVIII half-life was 3.9 hours (0.7-15.9 hours). FVIII was normalized (≥0.50 IU.mL-1) in 224/327 PWMHs (69%) and the median time with normalized FVIII was 3.9 hours (0.0-54.1 hours). Following the response profiles to DDAVP defined by the four efficacy scores, four groups of F8 variants were isolated, and then compared using survival curves with normalized FVIII (p < 0.0001): "long-lastingly effective" [p.(Glu739Lys), p.(Ser2030Asn), p.(Arg2178His), p.(Gln2208Glu), and T-stretch deletion in intron 13]; "moderately effective" [p.(Ser112Phe), p.(Ala219Thr), p.(Thr2105Ile), p.Phe2146Ser), and p.(Asp2150Asn)]; "moderately ineffective" [p.Ala81Asp), p.(Gln324Pro), p.(Tyr492His), p.(Arg612Cys), p.(Met701Val), p.(Val2035Asn), and p.(Arg2178Cys)]; and "frequently ineffective" [c.-219C > T, p.(Cys2040Tyr), p.(Tyr2169His), p.(Pro2319Leu), and p.(Arg2326Gln)]. CONCLUSION: In view of our data, we propose indications for DDAVP use in PWMH based on F8 variants for minor and major invasive procedures.

Type 2N von Willebrand disease: Genotype drives different bleeding phenotypes and treatment needs.

BACKGROUND: Von Willebrand disease type 2N (VWD2N) is usually perceived as a mild bleeding disorder that can be treated by desmopressin (DDAVP). However, VWD2N-patients can be compound heterozygous or homozygous for different variants, p.Arg854Gln (R854Q) being the most frequent causative one. There is limited data about the impact of 2N-variants on VWD2N phenotype and DDAVP-response. OBJECTIVES: To describe the phenotype of VWD2N, including DDAVP-response, according to genotype. PATIENTS/METHODS: VWD2N-patients with a complete genotype/phenotype characterization by the French reference center for VWD, including MCMDM-1VWD bleeding score (BS) were eligible to the study. Results of DDAVP-trial were also collected. RESULTS: A total of 123 VWD2N-patients from the French registry were included in this study. Results were stratified according to the presence (R854QPos, n=114) or absence (R854QNeg, n=9) of at least one R854Q-allele. Three R854QPos-subgroups were further individualized: patients homozygous (R854QHmz, n=55), compound heterozygous for R854Q and a null allele (R854Q/3, n=48) or compound heterozygous for R854Q and another 2N variant (R854Q/2N, n=11). FVIII: C levels were significantly lower in R854QNeg- and R854Q/3-patients compared to R854QHmz-ones (p<0.001 and p<0.0001 respectively). R854QNeg-patients were diagnosed earlier due to bleeding symptoms and had a higher BS than R854QPos-patients (p<0.001). In DDAVP-trial, FVIII:C survival was lower in VWD type 2N than in type 1. R854QPos-patients had a heterogeneous DDAVP-response, which was best predicted by baseline FVIII:C level. CONCLUSION: The heterogeneous genetic background of VWD2N drives different bleeding phenotypes and response patterns to DDAVP, underlining the clinical relevance of DDAVP-trial to identify patients potentially eligible to alternative therapeutic options.

Exudative retinopathy, cerebral calcifications, duodenal atresia, preaxial polydactyly, micropenis, microcephaly and short stature: a new syndrome?

The association of Coats disease with intrauterine growth retardation, intracranial calcification, leukodystrophy, brain cysts, osteopenia, and gastrointestinal bleeding defines Coats plus syndrome caused by mutations in the CTC1 gene, encoding conserved telomere maintenance component 1. Here, we report on a child with exudative retinopathy, cerebral calcifications, duodenal atresia, preaxial polydactyly, micropenis, microcephaly, and short stature, in whom no mutations in CTC1 were found. Our patient shares some features seen in other diseases associated with telomere shortening including Hoyeraal-Hreidarsson and Revesz syndromes. We therefore measured telomere length by Flow-Fish which was normal. The association of duodenal atresia and microcephaly also suggested a diagnosis of Feingold syndrome. However, direct sequencing of MYCN was normal, and we did not detect any hemizygous deletion of the miR-17∼92 polycistronic miRNA cluster. To our knowledge, the phenotype we report on has not been described previously, leading us to speculate that this condition may represent a new syndrome.

ADAM15 to α5ß1 integrin switch in colon carcinoma cells: a late event in cancer progression associated with tumor dedifferentiation and poor prognosis.

ADAM15, a member of the A Disintegrin And Metalloproteinase (ADAM) family, is a membrane protein containing an adhesion domain that binds to α5ß1 integrin through a unique RGD domain. ADAM15, expressed by human normal colonocytes, is involved in epithelial wound healing and tissue remodeling in inflammatory bowel disease. The aims of our study were (i) to analyze ADAM15 expression in a series of colon carcinomas and paired normal mucosa and (ii) to integrate the spatial relationship of ADAM15 with its binding partners α5ß1 integrin, a mesenchymal marker, as well as with other adhesion molecules, α3ß1 integrin and E-cadherin. A series of 94 colon carcinomas of the non other specified category were graded according to the World Health Organization classification. Immunohistochemistry was performed on frozen tissue sections using antibodies directed to ADAM15, α5ß1 and α3ß1 integrins, and E-cadherin. ADAM15 was quantified at the mRNA level. Finally, promoter methylation of ADAM15 was examined as well as the microsatellite instability status (MSS/MSI). Thirty-six percent of colorectal carcinomas displayed a reduced expression of ADAM15 in cancer cells, confirmed at the mRNA level in most cases, without promoter methylation. ADAM15 down-regulation was associated with histologically poorly differentiated carcinomas. In addition, it was associated with the acquisition of α5ß1 by cancer cells and down-regulation of α3ß1 integrin and E-cadherin. Finally this profile that includes characteristic of epithelial to mesenchymal transition is a late progression event of colon cancer with a poor prognosis.