The TAPS Support Foundation is dedicated to raising awareness and providing support for families affected by Twin Anemia Polycythemia Sequence (TAPS), while also advocating for improved care and research related to this condition.

Stickler Involved People (SIP) is a support group for individuals with Stickler Syndrome, providing educational resources, virtual support groups, and community events to help those affected by this connective tissue disorder.

Stickler Syndrome UK is a charity focused on supporting individuals affected by Stickler Syndrome, a genetic condition impacting connective tissue, and provides resources and guidance to improve quality of life.

The organization provides support for individuals affected by Stiff Person Syndrome (SPS), including their families and caregivers, while promoting education and research about the condition.

The Stiff Person Syndrome Research Foundation supports research and raises awareness for Stiff Person Syndrome (SPS), a neurological disease, while providing education and community support.

The Sturge-Weber Foundation aims to improve the quality of life and care for individuals with Sturge-Weber syndrome and associated Port-Wine Birthmark conditions through collaboration, education, advocacy, and research.

The SADS Foundation supports families affected by genetic heart conditions that can lead to sudden death due to arrhythmias, providing resources, research, and advocacy.

Sudden Infant Death Services of Illinois supports families who have lost a baby under the age of 1 year and provides safe sleep education to reduce sleep-related deaths.

The SUDC Foundation is dedicated to raising awareness, funding research, and providing support for families affected by sudden unexplained death in childhood (SUDC). They offer various services at no cost to those they serve.

Sundial Special Vacations provides travel excursions specifically designed for people with special needs and disabilities, ensuring a supportive and enjoyable experience for their clients.

The Superficial Siderosis Research Alliance (SSRA) is dedicated to supporting research, advocacy, and education for individuals affected by superficial siderosis, an ultra-rare neurodegenerative disorder.

SOFT UK is dedicated to providing support for families affected by Trisomy 13 and Trisomy 18, ensuring they have access to resources and a safe space to share their experiences.

SOFT is a patient advocacy organization that supports families with children diagnosed with Trisomy 18, 13, and related chromosomal disorders by providing resources, information, and a supportive community.

SPOHNC is dedicated to raising awareness and meeting the needs of oral and head and neck cancer patients through its resources and publications.

SAKKS supports families and caregivers of children with Kabuki Syndrome by providing information, resources, and community connections.

Riksförbundet Sällsynta diagnoser is an advocacy organization in Sweden that works to improve conditions for individuals with rare health conditions and their families, representing their interests to decision-makers and enhancing healthcare and support services.

The TANGO2 Research Foundation is dedicated to improving the lives of those affected by TANGO2 deficiency disorder through research, advocacy, and support for families.