Short communicationIdentification of a novel deletion in SURF1 gene: Heterogeneity in Leigh syndrome with COX deficiency

•The identification of a novel deletion in SURF1 gene, abolishing the initiation codon•The novel SURF1 deletion is predicted to modify Surf1p.•Assembled complex IV monomers are absent in mutant P1 and P2 fibroblasts.•Patient 1 is the oldest patient ever reported with LS associated to SURF1 mutations.

Leigh syndrome (LS) is a rare, progressive neurodegenerative mitochondrial disorder of infancy. It is a genetically heterogeneous disease. The mutations in SURF1 gene are the most frequently known cause. Here two cases of LS likely caused by SURF1 gene variants are reported: a 39-year-old male patient with a novel homozygous deletion (c.-11_13del), and a case of a 6-year-old boy with the same deletion and a nonsense mutation (c.868dupT), both in heterozygosity. Blue native PAGE showed absence of assembled complex IV. This is the first report of a variant that may abolish the SURF1 gene initiation codon in two LS patients.