1. ¹Willink Unit for Biochemical Genetics, Department of Paediatrics, Royal Manchester Children's Hospital, Manchester, UK
2. ²Department of Haematology/BMT, Royal Manchester Children's Hospital, Manchester, UK
3. ³Department of Paediatric Oncology/BMT, Our Lady's Hospital for Sick Children, Dublin, Ireland

Correspondence: Dr RF Wynn, Department of Haematology/BMT, Royal Manchester Children's Hospital, Manchester, M27 4HA, UK. E-mail: robert.wynn@cmmc.nhs.uk

Received 9 October 2006; Revised 16 November 2006; Accepted 20 November 2006; Published online 15 January 2007.

Abstract

Hurler Syndrome is corrected by allogeneic BMT by the action of donor enzyme on recipient tissue. In this paper, we describe monitoring of 39 patients transplanted in two centres to determine donor chimerism, enzyme level and residual substrate – expressed as dermatan sulphate to chondroitin sulphate ratio. We show that in fully engrafted recipients, the enzyme level, expressed as mol/g total protein/h, post-transplant is 24.2 from an unrelated donor and 10.2 from a heterozygote family donor (P<0.0001). There is a tight relationship between mean post-transplant enzyme level and residual substrate – Spearman's rank correlation coefficient (Rho) was -0.76 and -0.80 at 12 and 24 months, respectively (P<0.0001). We propose that these differences affect patient outcome. As unrelated donor transplant outcomes improve and especially given the higher levels of donor cell engraftment following cord transplants, our data might influence donor selection where only heterozygote-matched family members are available.