A CASE DIAGNOSED WITH MITOCHONDRIAL DISEASE CAUSED BY SURF1 MUTATION BY CANDIDATE GENE METHOD

Mitochondrial diseases are disorders that result from a deficiency of oxidative phosphorylation. It is
caused by pathogenic variants in nuclear (nDNA) or mitochondrial DNA (mtDNA). More than 350
genes from both mtDNA and nDNA cause mitochondrial diseases. Mutations in SURF1 can cause
damage to the basal ganglia, thalamus, brainstem, cerebellum, and peripheral nerves, resulting in
Leigh syndrome (LS), a subacute neurodegenerative encephalopathy. Herein, we present a 9-year-old
female patient whose parents were distantly related and who was followed for many years in the
pediatric neurology outpatient clinic for neuromotor developmental delay and seizures. Cranial MRI
showed bilateral symmetric basal ganglia involvement. Whole exome sequencing (WES) analysis of
our case demonstrated a homozygous mutation in SURF 1 gene NM_003172.4 c.870dupT(p.K291*)
(p.Lys291Ter). The case was diagnosed with Leigh`s syndrome. In conclusion; evaluation of cases
presenting with neuromotor developmental delay and seizure in early period of life should be
investigated for possible mitochondrial disease and should be diagnosed and treated in early period.