Regardless of these two possibilities, the normal serum electrolyte levels in some studies could be attributed not to the manifestation of ion concentration abnormalities in patients younger than 3 years.29 Lack of recognition of ID in 65% of the investigated cases could be because that ataxia and hearing loss make the cognitive assessment of the patients harder.16 However, it has been posited that ID is not an indispensable result of KCNJ10 mutations,30 mirrored in our results (35%; Table S2.1). This evidence concerns the gene KCNJ10 and cerebellar ataxia.