With interest we read the article by Cardenas-Robledo et al (1) regarding 2 patients with maternally inherited diabetes and deafness (MIDD) who presented with multisystem involvement, including vestibular impairment. We have the following comments and concerns. As the authors point out in their introduction, numerous organ systems are affected in patients with MIDD. These are summarized in Table 1.TABLE 1.: Phenotypic manifestations of MIDDRegarding the reported patients by Cardenas-Robledo et al, did the authors search for subclinical involvement of the gastrointestinal tract and kidneys? With regard to Patient 2, one would expect a sensory problem with regard to the bilateral thalamic lesions. Did the patient report any sensory problems or were any detected on recording of somatosensory-evoked potentials? Did Patient 2 undergo magnetic resonance spectroscopy to search for the nature of the thalamic lesions? Interestingly, Patient 2 developed rhabdomyolysis on administration of statins suggesting that statin myopathy develops particularly in patients with a mitochondrial disorder with myopathy. Which statin over what timeframe was given? What was the dosage? Were additional triggers, such as infection, ruled out as a cause of rhabdomyolysis? Both patients were reported to have cerebral atrophy. What were the clinical manifestations of cerebral atrophy? Did patients undergo neuropsychological testing to see if there was cognitive impairment or not? There are also patients with MIDD who progressed over time and developed phenotypic features of mitochondrial encephalopathy lactacidosis and stroke-like episodes (MELAS) (21). Did either patient develop typical features of MELAS syndrome, such as stroke-like episodes, seizures, vomiting, migraine-like headache, or cardiomyopathy during their disease course? It should be pointed out that the mtDNA mutation m.3243A>G is present in only 85% of the patients with MIDD (22). Other mutations causing MIDD include mtDNA mutations m.9267G>C (8), m.1555A>G (14), m.14530T>C (23), m.14709T>C (24), or m.3421G>A (25). Overall, these 2 interesting cases add much to the phenotypic spectrum of patients with MIDD. MIDD is a multisystem, syndromic mitochondrial disorder requiring the collaboration of various specialists to establish the correct diagnosis and provide optimal patient management.