Diabetes Care, Vol 17, Issue 7 728-733, Copyright © 1994 by American Diabetes Association
Biochemical and molecular studies of mitochondrial function in diabetes insipidus, diabetes mellitus, optic atrophy, and deafness
MJ Jackson, LA Bindoff, K Weber, JN Wilson, P Ince, KG Alberti and DM Turnbull
Division of Clinical Neuroscience, University of Newcastle upon Tyne, U.K.
OBJECTIVE--To determine if diabetes insipidus, diabetes mellitus, optic
atrophy, and deafness (DIDMOAD) combined with a cerebellar syndrome is
associated with a systemic disorder of respiratory chain function as found
in similar genetic syndromes. CASE--A muscle biopsy was taken from a
patient with DIDMOAD, and a mitochondrial fraction was prepared.
Respiratory chain function was assessed by analysis of intermediary
metabolites, histochemical analysis of muscle biopsy, measurement of the
activity of individual respiratory chain complexes, oxidative flux through
the respiratory chain, and cytochrome concentration and compared with a
population with normal respiratory chain function. Mitochondrial DNA from
skeletal muscle, brain, and pancreas was examined for major rearrangements
and specific point mutations. Brain tissue was examined neuropathologically
for abnormalities, particularly those previously described in association
with DIDMOAD. RESULTS--No abnormality was found in mitochondrial oxidation,
individual complex activity, or cytochrome concentration. Histochemical
analysis and electron microscopy showed no abnormality known to be
associated with mitochondrial dysfunction. A single-base substitution at
position 12308 of the mitochondrial genome was found, but no major
rearrangement of mitochondrial DNA was demonstrated. Neuropathological
examination revealed severe demyelination and gliosis in the optic nerves
and loss of Purkinje cells associated with gliosis in the white matter in
the cerebellum. CONCLUSIONS--We have found no evidence that DIDMOAD is
associated with a systemic abnormality of respiratory chain function. The
mitochondrial DNA single-base substitution noted is likely to be a
polymorphism rather than a pathogenic point mutation. We have confirmed
that DIDMOAD may be associated with a neurodegenerative disorder, but the
cause of this remains undetermined.