The Children's Mitochondrial Disease Network supports families and professionals in raising awareness and understanding of mitochondrial disorders.

The CNS Foundation is dedicated to finding treatments and cures for children suffering from neurological disorders, providing resources and education to families and healthcare professionals.

COTA supports families with children and young adults on a transplant journey by providing fundraising assistance and family support to help remove financial barriers associated with life-saving transplants.

The Children's Tumor Foundation is a nonprofit organization that supports patients and families affected by neurofibromatosis and schwannomatosis, focusing on patient support, awareness, and research funding.

The Children's Tumor Foundation supports patients and families affected by neurofibromatosis and schwannomatosis, focusing on patient support, awareness, and research funding.

This organization supports children with spinal muscular atrophy (SMA) by providing resources, advocacy, and facilitating research and treatment options.

Chloe's Fight Rare Disease Foundation advocates for children with rare diseases, focusing on raising awareness and supporting research initiatives.

The Chordoma Foundation supports individuals affected by chordoma by providing resources, patient navigation services, and facilitating connections within the chordoma community.

The Choroideremia Research Foundation (CRF) is dedicated to supporting research for choroideremia (CHM), a rare inherited disorder that causes progressive vision loss, and aims to find a cure or treatment for affected individuals.

Chromosome 18 Support and Resources is dedicated to supporting families affected by Chromosome 18 conditions through education, research, and community building.

Chromosome Disorder Outreach, Inc is a non-profit organization that supports individuals and families affected by rare chromosome and gene disorders through education, advocacy, and information.

The CRMO Foundation supports patients with Chronic Recurrent Multifocal Osteomyelitis (CRMO) by promoting research, providing education, and fostering community connections.

The CSS Association advocates for individuals affected by Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis) by providing resources, support, and raising awareness about the disease.

CID - Central Institute for the Deaf supports children who are deaf and hard of hearing by providing education and resources to help them learn to listen, talk, and succeed.

Citrin Foundation is a non-profit organization focused on tackling citrin deficiency, a genetic metabolic disorder, by funding research and providing support to affected patients and their families.

CJD Aware is an online information center for Creutzfeldt-Jakob Disease (CJD).

The Clear Cell Sarcoma Foundation is dedicated to making clear cell sarcoma survivable through education and research, while providing support for patients and caregivers affected by this ultra-rare cancer.

The Cleft Lip & Palate Association supports, connects, and empowers individuals affected by cleft lip and palate in the United Kingdom, providing information, resources, and community support.