الفهرس 
Title : Evaluation of Immune Response to Hepatitis B vaccine in Children with Down syndrome
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Abstract
Background: Down syndrome is the most common numerical chromosomal
disorder. Diagnostic criteria include hypotonia, intellectual disability, growth
retardation, delayed motor and mental development, facial dysmorphism and
associated congenital malformations particularly congenital heart disease.
Down syndrome children have high incidence of respiratory tract infections,
some hematologic malignancies particularly leukemia , and autoimmune
disorders that may result in an immune defect, Abnormalities in the blood Band
T-cell compartments, as well as lower IgM, IgG2, and IgG4 levels and
poor immunoglobulin responses to vaccines, have been found in some studies.
Infection with viral hepatitis B and C causes serious diseases in children all
over the world. The HBV vaccine reduces the number of chronic carriers and
eliminates persistent HBV infection and chronic liver disease, limiting
infection transmission to susceptible contacts. The aim of this study was to
evaluate the HBV immune status in children with Down syndrome and follow
the children whose HBsAb titre level was less than10 mIU/ml after giving them
a booster dose of HBV vaccine.
Methods: This cross sectional study included 166 Down syndrome, trisomy 21
children. All children were diagnosed by karyotyping. Next they were tested
for the level of HCV antibodies and HBsAb titre. Children with HBsAb titre
≤10 mIU/ml received a booster dose of HBV vaccine and were reevaluated
after one month.
Results: Twenty four children out of a total of the 166 Down syndrome,
trisomy 21, children (14.5%) showed HBsAb titre ≤10, After one month of
giving HBV vaccine to the low HBsAb titre group (24 children) the mean value
of HBsAb titre increased ranging from 10 to 1000 (only one child had HBsAb
titre 10 after the booster dose). The low HBsAb titre group had significantly
higher mean age compared to the high HBsAb titre group (p value =0.04). Out
of the 166 included Down syndrome, children there were 100 (60.2%) males
and 66 (39.8%) females with male predominance (male/female=1.5\1). Eight
children out of a total of the 166 Down syndrome , children (4%) had positive
HCV antibodies which were confirmed by HCV PCR , no significant
difference was noticed between both groups regarding the HCV antibody test (
P value = 1).
Conclusion: We conclude that Down syndrome children have an adequate
increase in HBsAb titre, but that despite initial adequate titers, the immune
response may wane over time and that long-term immunity in Down syndrome
children may not be preserved, so clinicians should follow and monitor all
children with Down syndrome who have been immunized against hepatitis B.