Harmonizing Perspectives on MPS II Care in Türkiye: A Delphi Study Towards Treatment Management Consensus

Background: Mucopolysaccharidosis type II (MPS II; Hunter syndrome) is a rare X-linked lysosomal storage disorder caused by pathogenic variants in the iduronate-2-sulfatase gene, leading to progressive multisystem involvement. Although international management guidelines exist, challenges in their implementation across different healthcare systems remain insufficiently addressed. This study aimed to establish a national expert consensus in Türkiye on the treatment and management of MPS II, aligning local practice with international standards. Methods: A modified Delphi methodology was conducted using two rounds of online surveys supported by three steering committee meetings. The process involved 10 experienced clinicians and a scientific committee of six professors. Based on international guidelines and country-specific clinical challenges, 72 consensus statements and 84 exploratory questions were developed. Statements achieving ≥ 80% agreement were accepted as consensus. Results: Consensus supported initiating enzyme replacement therapy (ERT) in both severe and attenuated MPS II, guided by functional and cognitive status. Severe cognitive impairment was not considered an exclusion criterion for ERT, given its somatic benefits. Experts agreed on continuing ERT into adulthood with individualized discontinuation decisions. Routine evaluations every 6-12 months, including respiratory, cardiac, and neurocognitive assessments, were recommended. Additional consensus areas included individualized premedication strategies, structured transition to adult care, selective home infusion, annual patient-reported outcome assessments, and the establishment of a national MPS II registry. Hematopoietic stem cell transplantation was not endorsed. Conclusions: This Delphi study demonstrates strong expert consensus on MPS II management in Türkiye, providing a practical framework to guide clinical practice, support alignment with international recommendations, and inform future policy and research priorities.