For “biomarker orphan” diseases, such as Rett syndrome and autism spectrum disorders (ASDs), Lp‐PLA2, which showed a significant inverse association only with individuals with ASDs compared with healthy controls, was identified as a novel serum biomarker for their differential diagnosis.229 The increased Lp‐PLA2 level in both obstructive sleep apnea (OSA) and obesity might adversely affect endothelial integrity, which decreased after OSA treatment. This evidence concerns the gene PLA2G7 and atypical Rett syndrome.