This was a retrospective review on 300 patients’ charts retrieved from Children’s Medical Center; identified by meeting the following search criteria: developmental regression, mitochondrial disease who had presented in the last 10 years and from the SURF1 family foundation. This led to 27 patients with SURF1. Informed consent and IRB approval was obtained.

The mean onset of symptoms was at 16 months of age and it took an average of 28 months from onset of symptoms to diagnosis. The most common symptom at onset was gross motor delay. Other neurologic manifestations in these patients' clinical course included intellectual disability (51.9%), ataxia (48.1%), hypotonia (33.3%), visual abnormalities (29.6%). Autism and aggression was uncommon. Seizures also manifested in a minority of our patients and when present were easily managed on no more than one AED. In terms of SURF1 mutations, 81% of the subjects were heterozygous and 19% were homozygous.  The most frequent mutation was c.312_321del110insAT. We did not see any correlation between serum lactate levels and clinical manifestations. MRI findings showed that the medulla and midbrain were the most commonly involved. In the midbrain significant involvement of the periaqueductal gray was seen followed by the substantia nigra. Thalamus was relatively spared in 85% of our group.   

The above results will help with diagnosing similarly presenting patients and future studies.