RAB40AL and mucopolysaccharidosis: Since the overlap of symptoms between the case reported by Lee et al. [4] and originally described patients [5] was only partial (out of nine features present in all three affected subjects from the first family [5], only four were present in the patient of Lee et al. [4]), the diagnosis rested mainly on the detection of the p.D59G mutation in the RAB40AL gene, which has been proposed to cause MPS [1].