A study of the neonatal haematology of children with Down syndrome

This thesis describes the establishment and initial findings of the Children with Down Syndrome Study, a birth cohort of children with DS. The Children with Down Syndrome Study was set up in order to characterise the haematology of neonates with Down syndrome and specifically to test the hypothesis that that this differed in this population. The study was carried out with the support of the Down Syndrome Association and the Down Syndrome Medical Interest Group, and through consultation with clinicians and families. Following a pilot study in the Yorkshire region it was established in over 60 hospitals across the north of England. The Children with Down Syndrome Study is the largest birth cohort of children with Down syndrome established to date, and this is the largest reported analysis of the haematology of neonates with Down syndrome. The results confirm that neonates with Down syndrome have a distinct haematological profile. Means and ranges for haematological parameters throughout the neonatal period are provided. The effects of gestational age, birth weight, postnatal age and the venepuncture to processing interval on the neonatal full blood count were examined, and this is the first report of factors that influence the haematological parameters in neonates with Down syndrome. In order to analyse the blood cell morphology a new approach to morphology was developed and validated. Morphological review of samples from neonates with Down syndrome demonstrated that blasts were common. Comparison with automated findings showed that manual review of a film is indicated to look for evidence of transient myeloproliferative disorder. This is also the largest longitudinal study of haematological parameters of children with Down syndrome beyond the neonatal period. The results showed that parameters changed between birth and 1 year, with most being stable thereafter. However, it appears that children with Down syndrome continue to have a distinct morphological profile.