Neonatal lupus is a novel cause of positive newborn screening for X‐linked adrenoleukodystrophy

We report three unrelated individuals, each exposed to maternal autoantibodies during gestation and found to have elevated very long‐chain fatty acids (VLCFAs) in the newborn period after screening positive by California newborn screening (NBS) for X‐linked adrenoleukodystrophy (ALD). Two probands presented with clinical and laboratory features of neonatal lupus erythematosus (NLE); the third had features suggestive of NLE and a known maternal history of Sjogren's syndrome and rheumatoid arthritis. In all three individuals, subsequent biochemical and molecular evaluation for primary and secondary peroxisomal disorders was nondiagnostic with normalization of VLCFAs by 15 months of age. These cases add to the expanding differential diagnosis to consider in newborns who screen positive for ALD via elevated C26:0‐lysophosphatidylcholine. Though the pathophysiology of how transplacental maternal anti‐Ro antibodies damage fetal tissue is not well‐understood, we postulate that the VLCFA elevations reflect a systemic inflammatory response and secondary peroxisomal dysfunction that improves once maternal autoantibodies wane after birth. Additional evaluation of this phenomenon is warranted to better understand the intricate biochemical, clinical, and possible therapeutic overlap between autoimmunity, inflammation, peroxisomal dysfunction, and human disease.