Maternally Inherited Leigh Syndrome and NARP Syndrome
You are reading a NORD Rare Disease Report Abstract. NORD’s full collection of reports on over 1200 rare diseases is available to subscribers (click here for details). We are now also offering two full rare disease reports per day to visitors on our Web site.
NORD is very grateful to Sumit Parikh, MD, Neurometabolic and Neurogenetics Staff Clinician, Cleveland Clinic, for assistance in the preparation of this report.
Synonyms of Maternally Inherited Leigh Syndrome and NARP Syndrome
- MILS-NARP syndrome
- maternally inherited Leigh syndrome (MILS)
- mtDNA-associated Leigh syndrome
- neuropathy, ataxia and retinitis pigmentosa (NARP)
Maternally inherited Leigh syndrome (MILS) and neuropathy, ataxia and retinitis pigmentosa (NARP) syndrome are rare genetic multisystem disorders that are part of a spectrum or continuum of disease caused by abnormalities affecting mitochondrial energy production. NARP is characterized by nerve disease affecting the nerves outside of the central nervous system (peripheral neuropathy), an impaired ability to coordinate voluntary movements (ataxia), an eye condition known as retinitis pigmentosa (RP), and a variety of additional abnormalities. MILS is generally a more severe mitochondrial disorder that often becomes apparent during infancy or childhood and is characterized by brain disease (encephalopathy), elevated levels of lactic acid in the body (lactic acidosis), seizures, heart disease (cardiomyopathy), breathing (respiratory) abnormalities, and developmental delays. The specific symptoms and severity of these disorders in each individual can vary greatly from one person to another and even among members of the same family.
MILS and NARP syndrome are maternally inherited mitochondrial disorders. They are caused by specific mutations affecting the mitochondrial gene known as the ATPase 6 gene. When individuals have more than 90 percent of mutated mitochondrial DNA (mtDNA) in their cells, they are classified as having MILS and not NARP syndrome. Most individuals with NARP syndrome have 70-80 percent of mutated mtDNA. In some families, one individual may have NARP syndrome while another individual is diagnosed with MILS. (For more information on mtDNA see the Causes section below.)
Mitochondrial disorders are characterized by mutations affecting the parts of the cell that release energy (mitochondria). Mitochondrial diseases often hamper the ability of affected cells to break down food and oxygen and produce energy. In most mitochondrial disorders, abnormally high numbers of defective mitochondria are present in the cells of the body. Mitochondrial diseases often affect more than one organ system of the body. NARP syndrome was first identified in the medical literature in 1990. Leigh syndrome was first reported in the medical literature in 1951.
Maternally Inherited Leigh Syndrome and NARP Syndrome Resources
NORD Member Organizations:
(To become a member of NORD, an organization must meet established criteria and be approved by the NORD Board of Directors. If you're interested in becoming a member, please contact Susan Olivo, Membership Manager, at email@example.com.)
The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.
The National Organization for Rare Disorders (NORD) web site, its databases, and the contents thereof are copyrighted by NORD. No part of the NORD web site, databases, or the contents may be copied in any way, including but not limited to the following: electronically downloading, storing in a retrieval system, or redistributing for any commercial purposes without the express written permission of NORD. Permission is hereby granted to print one hard copy of the information on an individual disease for your personal use, provided that such content is in no way modified, and the credit for the source (NORD) and NORD’s copyright notice are included on the printed copy. Any other electronic reproduction or other printed versions is strictly prohibited.
Copyright 2005, 2013
NORD's Rare Disease Information Database is copyrighted and may not be published without the written consent of NORD.