High fetal hemoglobin level is associated with increased risk of cerebral vasculopathy in children with sickle cell disease in Mayotte

Background

Understanding the genetics underlying the heritable subphenotypes of sickle cell anemia, specific to each population, would be prognostically useful and could inform personalized therapeutics.The objective of this study was to describe the genetic modulators of sickle cell disease in a cohort of pediatric patients followed up in Mayotte.

Methods

This retrospective cohort study analyzed clinical and biological data, collected between January1^st2007 and December 31^st2017, in children younger than 18 years.

Results

We included 185 children with 72% SS, 16% Sβ0-thalassemia and 12% Sβ + thalassemia. The average age was 9.5 years; 10% of patients were lost to follow up. The Bantu haplotype was associated with an increase in hospitalizations and transfusions. The alpha-thalassemic mutation was associated with a decrease of hemolysis biological parameters (anemia, reticulocytes), and a decrease of cerebral vasculopathy. The Single Nucleotide Polymorphisms BCL11A rs4671393, BCL11A rs11886868, BCL11A rs1427407 and HMIP rs9399137 were associated with the group of children with HbF > 10%. Patients with HbF > 10% presented a significant risk of early onset of cerebral vasculopathy.

Conclusions

The most remarkable result of our study was the association of SNPs with clinically relevant phenotypic groups. BCL11A rs4671393, BCL11A rs11886868, BCL11A rs1427407 and HMIP rs9399137 were correlated with HbF > 10%, a group that has a higher risk of cerebral vasculopathy and should be oriented towards the hemolytic sub-phenotype.

[Malignancy risk and Wiedemann-Beckwith syndrome: what follow-up to provide?]

Wiedemann-Beckwith syndrome (WBS) is a syndrome of excessive growing with a high predisposition to developing embryologic tumours within the first years of life. This risk is evaluated between 7.5 and 10%; it varies with the mechanisms of mutations involved. These take place in two distinct domains of 11p15, which are under parental printing. Emerging techniques of cytogenetic and molecular biology now have shown correlations between genotypes and phenotypes, and can identify the 30% of WBS who are especially at risk of developing tumours. A specific follow-up, integrating the specificity of developing tumours of each 11p15 mutations involved, is now proposed to patients with WBS.

Vaccination de l'enfant contre l'hépatite B à Mayotte, île française des Comores

Hepatitis B virus (HBV) is responsible for a worldwide mortality of 1 million people each year. It constitutes a major public health problem, especially in highly endemic zones, where it concerns the youngest children, primarily by a mother to child transmission, with a strong risk of chronic hepatitis infection and hepatocellular carcinoma. Immunisation of children versus HBV is known to be efficient and safe. In Mayotte, a French overseas territory in Indian Ocean, immunisation versus HBV has been introduced since 1993 in the vaccine schedule, starting at day 1 of life. We report hereby the local experience and practice on HBV infection, state of vaccine coverage, and difficulties met with this major public health issue.

[Multifocal infection due to Mycobacterium intracellulare: first case of interferon gamma receptor partial dominant deficiency in tropical French territory]

Nontuberculous mycobacterial infections are rare in immunocompetent children, and usually present as adenitis. We report a case of a 6-year-old girl with a multifocal chronic osteomyelitis and pulmonary localisation due to Mycobacterium intracellulare associated with an autosomal dominant mutation of interferon gamma receptor 1 gene (INFGR1) leading to a syndrome of mendelian predisposition to mycobacteria infections by partial deficiency of intracellular signalisation of gamma interferon. This child has been cured with anti-mycobacteria drugs and gamma interferon. This report focus on the importance of looking for a susceptibility of the host to infectious diseases, which can lead to a specific treatment. As far as we know, this is the first case described in a tropical area.