Deciphering an Adenovirus F41 Outbreak in Pediatric Hematopoietic Stem Cell Transplant Recipients by Whole-Genome Sequencing.

Human adenovirus (HAdV) represents a major cause of mortality and morbidity in pediatric recipients of allogeneic hematopoietic stem cell transplants (HSCT). HAdV species F type 41 (HAdV-F41) infections in HSCT patients are scarce, whereas HAdV-F41 circulates commonly in healthy individuals. Between March and July 2018, HAdV-F41 infections were identified in four children (A, B, C, and E) who received allogeneic HSCT and one child before HSCT (D) at Robert Debré Hospital, Paris, France. We report here the clinical course of HAdV-F41 infection and the phylogenetic investigation to identify interpatient transmission. HAdV DNA was quantified in stool and plasma samples by real-time PCR. HAdV type was determined by sequencing of the fiber and hexon genes. Phylogenetic investigation was done with whole-genome sequences obtained by next-generation sequencing. HAdV loads in stool samples ranged from 6.60 to 10.10 log10 copies/ml. HAdV-F41 detection in plasma was observed in four patients, but no disseminated disease was reported. Two patients died, but neither death was attributed to HAdV. While sequencing limited to the fiber gene suggested a cluster with four patients, phylogenetic analysis with whole-genome sequencing (WGS) and HVR7 revealed a cluster that included three patients (C, D, and E), suggesting an interpatient transmission in that cluster and two other independent infections. HAdV-F41 levels in stool specimens of pediatric HSCT patients are high and represent a risk of interpatient transmission. WGS helped to identify related cases. Prompt detection of HAdV in stool and control measures are warranted to limit any risk of nosocomial transmission.

Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update.

Children with constitutional trisomy 21 (Down syndrome (DS)) have a unique predisposition to develop myeloid leukaemia of Down syndrome (ML-DS). This disorder is preceded by a transient neonatal preleukaemic syndrome, transient abnormal myelopoiesis (TAM). TAM and ML-DS are caused by co-operation between trisomy 21, which itself perturbs fetal haematopoiesis and acquired mutations in the key haematopoietic transcription factor gene GATA1. These mutations are found in almost one third of DS neonates and are frequently clinically and haematologcially 'silent'. While the majority of cases of TAM undergo spontaneous remission, ∼10 % will progress to ML-DS by acquiring transforming mutations in additional oncogenes. Recent advances in the unique biological, cytogenetic and molecular characteristics of TAM and ML-DS are reviewed here.

Biliary atresia: Clinical advances and perspectives.

Biliary atresia (BA) is a rare and severe inflammatory and obliterative cholangiopathy that affects both extra- and intrahepatic bile ducts. BA symptoms occur shortly after birth with jaundice, pale stools and dark urines. The prognosis of BA has dramatically changed in the last decades: before the Kasai operation most BA patients died, while nowadays with the sequential treatment with Kasai operation±liver transplantation BA patient survival is close to 90%. Early diagnosis is very important since the chances of success of the Kasai procedure decrease with time. The causes of BA remain actually unknown but several mechanisms including genetic and immune dysregulation may probably lead to the obliterative cholangiopathy. Current research focuses on the identification of blood or liver factors linked to the pathogenesis of BA that could become therapeutic targets and avoid the need for liver transplantation. No similar disease leading to total obstruction of the biliary tree exists in older children or adults. But understanding the physiopathology of BA may highlight the mechanisms of other destructive cholangiopathies, such as sclerosing cholangitis.