Table 1 Draft statements composed by the planning committee

1.

All patients should be genotyped at diagnosis as this may help in (future) decision-making on therapeutic strategies.

2.

Patients homozygous or compound heterozygous for mutations clearly associated with MPS I-H (e.g. W402X, Q70X) should be referred for HSCT.

3.

Patients diagnosed before the age of 2.5 years based on clinical signs and symptoms compatible with MPS I-H (i.e. early kyphosis and/or characteristic facial features and/or CNS-involvement) should be referred for HSCT.

4.

HSCT is more successful if performed early and should probably be done after the age of 3 months, as soon as a suitable donor is available.

5.

All patients with MPS I should be tested by an experienced child (neuro-)psychologist for developmental quotient at diagnosis. Tests should be adapted for physical limitations (e.g. auditory or visual handicaps). If there is significant developmental delay (DQ < 70) before transplant, the outcome of HSCT on final IQ is likely to be limited. Not performing HSCT in these patients should be considered as an option.

6.

There is yet no evidence that HSCT is the optimal treatment for patients with MPS I-H/S and MPS I-S (patients diagnosed on the basis of first significant clinical signs and symptoms > 2.5 years and a genotype not indicating MPS I-H). A randomized controlled trial should elucidate if HSCT is the optimal strategy for these patients.

7.

All patients that are not transplanted may benefit significantly from ERT.

8.

As the efficacy of ERT improves if initiated at an early age, ERT should be started at diagnosis.

9.

There is no evidence that a dose other than the recommended dose (100 IU/kg weekly) of alpha-L-iduronidase is superior. A randomized controlled trial will be the best strategy to elucidate the optimal dose.

10.

Patients who will be/are referred for HSCT may benefit from ERT before HSCT as this can improve the clinical condition of the patient.

11.

There is no evidence that ERT before HSCT interferes with engraftment.

12.

There is no evidence that ERT after a successful HSCT will improve clinical outcome.