Recessive mutations in the MSTO1 gene, encoding for a mitochondrial distribution and morphology regulator, have been recently described in 4 families with multisystem involvement, mostly characterized by myopathy or dystrophy, cerebellar ataxia, pigmentary retinopathy and raised CK. Here we report a patient with recessive MSTO1 gene related muscular dystrophy and ataxia. The patient, born to non-consanguineous parents, presented at age 2 years with global developmental delay. At age 15 years he was ambulant and showed axial, upper and lower limb weakness, pronounced proximally, scoliosis, ankle contractures and ataxia. There was no cardiac or respiratory involvement. EMG was normal. Brain MRI at 6 years showed cerebellar atrophy and mild under-opercularisation of the left Sylvian fissure; when repeated at 9 years, there was mild progression of cerebellar atrophy and additional supratentorial sulcal prominence suggestive of volume loss. Muscle MRI showed generalized increase in T1 signal in the lower limb with normal STIR sequences. CK was raised (800-1614 IU/L). Muscle biopsy showed fibre size variability, increased internal nuclei, fatty endomysial infiltration, few regenerating fibres, type 1 predominance and some minicores. Minor changes of uncertain significance on laminin-α and a-dystroglycan staining were observed. Respiratory chain enzyme studies were normal. Whole-exome sequencing revealed 2 missense MSTO1 variants. The first variant (c.766C>T p.(Arg256Trp)), affecting a conserved residue in the tubulin domain of the protein, is reported in the gnomAD dataset with an allelic frequency of 0.00003, while the second (c.1435C>T p. (Pro479Ser)) is novel. In silico tools predict both variants as damaging. Phasing of the variants is in progress. This case confirms a consistent phenotype associated with recessive MSTO1 gene mutations and suggests that progressive cerebellar atrophy can be a feature of the condition.