Response to: Phenotypic heterogeneity of Leigh syndrome due to NDUFA12 variants is multicausal. Issue 1 (9th December 2021) - Torraco, Alessandra; Maroofian, Reza; Rötig, Agnès; Bertini, Enrico; Ghezzi, Daniele; Carrozzo, Rosalba; Diodato, Daria