International clinical evidence-based guideline for Kleefstra syndrome.

Kleefstra syndrome (KLEFS1) is a rare monogenic neurodevelopmental disorder with multisystem involvement, caused by disruption of EHMT1 function, resulting in significant burden on affected individuals and their families. The current shortage of and globally scattered syndrome-specific knowledge has led to significant disparities in the access to and provision of evidence-based and individual-centered expert care. To address the challenges and improve outcomes for individuals with KLEFS1, an international KLEFS1 guideline consortium was formed consisting of 43 participants, both clinical experts and patient representatives, from 15 different countries. The primary goal of the consortium was to develop a comprehensive and high-quality guideline for KLEFS1, aiming to enhance patient care, establish a uniform minimum international standard of care, and support decision making.The current clinical guideline is evidence-based and includes 66 tailored recommendations to improve KLEFS1 care. The comprehensive methodological approach ensures broad consensus and supports effective implementation. Furthermore, this guideline serves as a valuable methodological model for guideline development in the context of rare disorders.