This organization supports individuals and families affected by Sheehan's Syndrome and postpartum Lymphocytic Hypophysitis by providing information, community support, and raising awareness about these maternal pituitary conditions.

Matheny Medical and Educational Center provides exceptional care and an optimal quality of life for children and adults with special needs and medically complex developmental disabilities through various programs including a hospital, school, and adult day program.

Matrix Parents is part of Marin CIL, serving families of children and young adults with disabilities in Marin, Napa, Solano, and Sonoma Counties, providing resources and support for various age groups.

Matthew's Friends is a UK registered charity that specializes in medical Ketogenic Dietary Therapies, supporting patients with drug-resistant epilepsy and other neurological and metabolic disorders through information, training, research, and grants.

The M-CM Network provides support and information for patients with macrocephaly-capillary malformation syndrome and promotes research and awareness about this rare genetic condition.

The MdDS Foundation supports individuals affected by Mal de Débarquement Syndrome (MdDS) through advocacy, awareness, and a patient registry to gather information and improve research efforts.

MD Support provides free information and personal assistance for individuals dealing with macular degeneration and similar retinal diseases.

The ME Association provides support and resources for individuals affected by ME/CFS and Long Covid, advocating for improved healthcare and conducting research to find effective treatments.

MEBO Research is a patient advocacy organization focused on initiating research into rare genetic metabolic diseases, particularly those causing systemic body malodor and halitosis, including Trimethylaminuria. They provide support and information through various studies and community engagement.

The MECP2 Duplication Foundation supports families affected by MECP2 Duplication Syndrome by providing information, resources, and funding for research aimed at finding a cure.

MECP2 Duplication UK is a charity that provides emotional, practical, and financial support to families affected by MECP2 Duplication Syndrome, while also raising awareness and promoting research into the condition.

The MED13L Foundation supports families affected by MED13L Syndrome, a rare genetic neurodevelopmental disorder, by providing awareness, family support, and advancing medical research.

MedicAlert Foundation provides 24/7 emergency response services and medical ID solutions to help individuals with medical conditions receive timely and accurate care during emergencies.

The Medicare Rights Center is a nonprofit organization that advocates for affordable health care access for older adults and people with disabilities through counseling, educational programs, and public policy initiatives.

The MEF2C Foundation focuses on accelerating research and developing treatments for MEF2C Haploinsufficiency Syndrome, a neurodevelopmental disorder, while providing support and information to affected families.

Melanin Children Matter advocates for medically underrepresented children, providing support and education for families facing rare diseases and emphasizing health equity and social justice.

The Melanoma Research Foundation (MRF) is dedicated to eradicating melanoma through research, education, and advocacy for patients and their families affected by this deadly form of skin cancer.

The Melorheostosis Association is dedicated to finding the cause, treatments, and cure for melorheostosis, a rare and progressive bone disorder, while promoting awareness and providing support for affected individuals and their families.

Memorial Sloan Kettering Cancer Center is dedicated to providing personalized cancer treatment and conducting cutting-edge research to improve cancer care and outcomes.

Mencap is a charity that supports individuals with learning disabilities, including Down syndrome and Williams syndrome, by providing information, advice, and advocacy services to help them lead fulfilling lives.