The diagnostic workup usually includes an MRI of the brain, an EEG, ophthalmic examination and a cardiac ECHO. Muscle biopsy – which is not commonly done – may show storage of abnormal material and secondary mitochondrial abnormalities in skeletal muscle. Other features that may be seen on muscle biopsy include variability in fibre size, increase in internal and centralized nuclei, type 1 fibre hypotrophy with normally sized type 2 fibres, increased glycogen storage and variable vacuoles on light microscopy The diagnosis is confirmed by sequencing of the EPG5. Differential diagnosis This includes ataxia–telangiectasia, Chédiak–Higashi syndrome, DiGeorge syndrome, Griscelli syndrome and Marinesco–Sjögren syndrome.
Vici syndrome
WAGR syndrome
TEMPI syndrome
Fryns-Aftimos syndrome
MERRF syndrome
Franceschetti–Klein syndrome
MELAS syndrome
STAR syndrome