Mitochondrial diseases result from failures of the mitochondria, which are specialized compartments present in every cell of the body except red blood cells. Mitochondria are responsible for creating more than 90% of the energy needed by the body to sustain life and support growth. When they fail, less and less energy is generated within the cell. Cell injury and even cell death follow. If this process is repeated throughout the body, whole systems begin to fail, and the life of the person affected is severely compromised. Mitochondrial diseases primarily affect children, but adult onset is becoming more and more common.

Mitochondrial diseases are challenging because they are probably the most diverse human disorders at every level: clinical, biochemical, and genetic. Some are confined to the nervous system but most are multi-systemic, often affecting the brain, heart, liver, skeletal muscles, kidney and the endocrine and respiratory systems. Although severity varies, by and large these are progressive and often crippling disorders. They can cause paralysis, seizures, mental retardation, dementia, hearing loss, blindness, weakness and premature death.

Because of the range of symptoms and the frequent involvement of multiple body systems, mitochondrial diseases can be a great challenge to diagnose. Even when accurately diagnosed, they pose an even more formidable challenge to treat, as there are very few therapies and most are only partially effective.

The North American Mitochondrial Disease Consortium (NAMDC) was established to create a network of clinicians and clinical investigators in North America who follow sizeable numbers of patients with mitochondrial diseases and are involved or interested in mitochondrial research. NAMDC has created a patient clinical registry in the hopes of standardizing diagnostic criteria, collecting important clinical information, and facilitating the participation of patients in research on mitochondrial diseases.

For the study of any rare disease, the collection of specimens is a major challenge. In order to make materials easily available to consortium researchers, NAMDC has established a repository for specimens and DNA from patients with mitochondrial diseases.

NAMDC also provides a virtual platform (www.namdc.org) led by a clinical investigator for remote enrollment of mitochondrial disease patients that are unable to visit one of the participating centers. The process includes diagnostic verification and electronic consent provided by the patient.

In addition to the US remote enrollment platform, NAMDC hosts the Latin American Mitochondrial Disease Registry (LAMDR), a separate section of the general registry at www.namdc.org/sp, that allows remote enrollment of Spanish‐speaking subjects residing in any Latin American countries. LAMDR excludes Portuguese and French‐speaking regions, unless mitochondrial patients from those regions are fluent in Spanish or English and able to provide informed consent and submit translated records to determine eligibility.

Finally, NAMDC conducts clinical trials and other research activities. The consortium makes biostatisticians, data management experts, and specialists in clinical research available to participating physicians, so that research conducted through the NAMDC can make the most efficient and innovative use of the generous participation of patients.

The challenge for the NAMDC is the extraordinary clinical spectrum of mitochondrial diseases, which all too often leads practitioners to either underdiagnose ("What is this complex disorder?") or overdiagnose ("This disorder is so complex that is must be mitochondrial!"). Yet mitochondrial diseases cause similar metabolic defects and presumably share—albeit to different extents—the same mechanisms. Thus, the availability of a mitochondrial patient registry and of a consortium will have a powerful impact in multiple ways, as already documented by similar organizations operating in Europe.

First, the NAMDC will make these rare and still unfamiliar diseases known to practitioners and to the general public.

Second, it will facilitate correct diagnosis by making "centers of excellence" available to physicians and affected families alike.

Third, it will offer affected families the comfort and advice of a patient support group, the United Mitochondrial Disease Foundation (UMDF).

Fourth, it will foster clinical research, such as natural history, that would be otherwise impossible because it requires relatively large cohorts of patients.

Fifth, it will also foster more basic research by revealing unusual patients, leading to the discovery of new genetic defects.

Finally, the NAMDC will conduct rigorous and innovative therapeutic clinical trials.