Myopathy, Mitochondrial Anomalies, and Ataxia

Background and History: 

This is an inherited abnormality of nervous system development.  Mitochondria, located inside cells, are often referred to as energy factories and they may be dysfunctional as well.  There is widespread dysfunction of the nervous system.

Clinical Correlations: 

Short stature and delayed nervous system with unsteadiness (ataxia) are seen from early childhood.  Patients may never walk and speech is often absent.  Muscles are weak and infants may appear "floppy".  Patients often have some intellectual disability.  The face appears elongated and facial muscles can appear frozen.  The lower jaw can be underdeveloped or enlarged while the palate is highly arched.  Some sensory (touch) deficits can be present and there may be random purposeless movements of the digits and limbs, including a tremor.  Behavioral abnormalities including anxiety, depression, and schizophrenia have been reported.

The eyes appear small and deeply set.  The retina may have abnormal pigmentation and the optic nerves  may be pale suggesting impaired visual function but visual acuities have not been reported.


Three families have been reported.  In two families genetic and pedigree studies suggest autosomal dominant inheritance in which the risk to additional sibs is 50%.  In the remaining family the gene mutation in both members of a specific gene are changed (mutated) consistent with autosomal recessive inheritance where the parents (presumably carrying a single mutation) have a 25% chance that each of their children would inherit this condition.

Diagnosis and Prognosis: 

This disorder likely has its onset prenatally although the evidence for neurological disease is likely subtle at birth.  Neurologists, pediatricians, and ophthalmologists should collaborate in the diagnosis.  As there is no single biochemical test that is useful to make the diagnosis ultimately genetic studies to identify the mutation is the only useful method to make the diagnosis.

No treatment has been reported.  Physical and speech therapy may be beneficial.

Additional Information
Autosomal dominant
Autosomal recessive