Assessment of persons who are carrier of a LHON (m.03460G>A, m.11778G>A or m.14484T>C) mutation in the mitochondrial DNA.

LHON stands for Leber's Hereditary Optic Neuropathy. It is a mitochondrial
disease that makes patients blind before their fifthieth year of life.
Mitochondrial dysfunction can be caused by a defect in the oxidative
phosphorylation (OXPHOS). The three most known LHON mutations (m.1778G>A,
m.14484T>C and m.03460G>A) in the mitochondrial DNA lead to reduced vision or
blindness in 50% of the men and 10% of the women. A small part of the patients
develop a more expanded disease with neurologic phenomena including muscle and
cardial problems; this is known as LHON plus.

The objective of the study is to map in a standardized way the phenotype of
carriers with known LHON mutations. We want to study the natural course of
persons with LHON mutations by examining patients several times. Further, we
want to study a couple of organ systems in detail in order to become an
overview of factors that contribute to development of vision or other
complaints in carriers of a LHON mutation.

It is a cohort study in which all people with a LHON mutation will be assessed
at a visit to our polyclinic using the Newcastle Mitochondrial Disease Adult
Scale (NMDAS) and the Newcastle Pediatric Mitochondrial Disease Scale (NPMDS).
We will repeat this assessment after 1, 2 and 4 year. Furthermore, a
comprehensive ophthalmological examination will take place.

The patients will be asked to come to the policlinic for a part of a day. The
Newcastle Mitochondrial Disease Adult Scale or the Newcastle Pediatric
Mitochondrial Disease Scale will be administered, which will take 45 minutes.
Further, there will be an ophthalmological examination, which takes about 1
hour. These visits will be repeated after 1, 2 and 4 year. The patients will be
requested to complete some questionnaires at home.