PLA2G7 and Rett syndrome: 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.