Adrenoleukodystrophy (ALD) is a rare X‐linked disease caused by a mutation of the peroxisomal ABCD1 gene. This review summarizes our current understanding of the pathogenic cell‐ and tissue‐specific roles of lipid species in the context of experimental therapeutic strategies and provides an overview of critical historical developments, therapeutic trials and the advent of newborn screening in the USA. In ALD, very long‐chain fatty acid (VLCFA) chain length‐dependent dysregulation of endoplasmic reticulum stress and mitochondrial radical generating systems inducing cell death pathways has been shown, providing the rationale for therapeutic moiety‐specific VLCFA reduction and antioxidant strategies. The continuing increase in newborn screening programs and promising results from ongoing and recent therapeutic investigations provide hope for ALD.

Early diagnosis of males with X-linked adrenoleukodystrophy (X-ALD) is essential for preventing loss of life due to adrenal insufficiency and for timely therapy of the childhood cerebral form of X-ALD with hematopoietic cell transplantation. This article describes X-ALD, the current therapies, the history of the development of the newborn screening test, the approval by the Secretary of Health and Human Services for the addition of X-ALD newborn screening to the recommended uniform panel of disorders screened as newborns (RUSP) and the successful implementation of X-ALD newborn screening in the state of New York beginning on 30 December 2013. Follow-up guidelines that have been established in New York are outlined. Based on the success of newborn screening in New York, and early results in Connecticut, where X-ALD newborn screening started in December 2015, and in California, where X-ALD newborn screening began in September 2016, we are confident and hopeful that X-ALD newborn screening will expand to include all US states and to countries that have established neonatal screening programs. The Minster of Health in the Netherlands has approved the addition of X-ALD to the newborn screening program with a start date expected in 2017. The states, such as Massachusetts, Illinois, Minnesota, New Jersey, Florida and Washington, that have legislative approval will commence screening as soon as budgetary resources, testing and follow-up procedures are in place.

Ethanolamine plasmalogens constitute a group of ether glycerophospholipids that, due to their unique biophysical and biochemical properties, are essential components of mammalian cellular membranes. Their importance is emphasized by the consequences of defects in plasmalogen biosynthesis, which in humans cause the fatal disease rhizomelic chondrodysplasia punctata (RCDP). In the present lipidomic study, we used fibroblasts derived from RCDP patients, as well as brain tissue from plasmalogen-deficient mice, to examine the compensatory mechanisms of lipid homeostasis in response to plasmalogen deficiency. Our results show that phosphatidylethanolamine (PE), a diacyl glycerophospholipid, which like ethanolamine plasmalogens carries the head group ethanolamine, is the main player in the adaptation to plasmalogen insufficiency. PE levels were tightly adjusted to the amount of ethanolamine plasmalogens so that their combined levels were kept constant. Similarly, the total amount of polyunsaturated fatty acids (PUFAs) in ethanolamine phospholipids was maintained upon plasmalogen deficiency. However, we found an increased incorporation of arachidonic acid at the expense of docosahexaenoic acid in the PE fraction of plasmalogen-deficient tissues. These data show that under conditions of reduced plasmalogen levels, the amount of total ethanolamine phospholipids is precisely maintained by a rise in PE. At the same time, a shift in the ratio between ω-6 and ω-3 PUFAs occurs, which might have unfavorable, long-term biological consequences. Therefore, our findings are not only of interest for RCDP but may have more widespread implications also for other disease conditions, as for example Alzheimer's disease, that have been associated with a decline in plasmalogens.

Peroxisome biogenesis disorders (PBD) are a group of multi-system human diseases due to mutations in the PEX genes that are responsible for peroxisome assembly and function. These disorders lead to global defects in peroxisomal function and result in severe brain, liver, bone and kidney disease. In order to study their pathogenesis we undertook a systematic genetic and biochemical study of Drosophila pex16 and pex2 mutants. These mutants are short-lived with defects in locomotion and activity. Moreover these mutants exhibit severe morphologic and functional peroxisomal defects. Using metabolomics we uncovered defects in multiple biochemical pathways including defects outside the canonical specialized lipid pathways performed by peroxisomal enzymes. These included unanticipated changes in metabolites in glycolysis, glycogen metabolism, and the pentose phosphate pathway, carbohydrate metabolic pathways that do not utilize known peroxisomal enzymes. In addition, mutant flies are starvation sensitive and are very sensitive to glucose deprivation exhibiting dramatic shortening of lifespan and hyperactivity on low-sugar food. We use bioinformatic transcriptional profiling to examine gene co-regulation between peroxisomal genes and other metabolic pathways and we observe that the expression of peroxisomal and carbohydrate pathway genes in flies and mouse are tightly correlated. Indeed key steps in carbohydrate metabolism were found to be strongly co-regulated with peroxisomal genes in flies and mice. Moreover mice lacking peroxisomes exhibit defective carbohydrate metabolism at the same key steps in carbohydrate breakdown. Our data indicate an unexpected link between these two metabolic processes and suggest metabolism of carbohydrates could be a new therapeutic target for patients with PBD. Peroxisomes are organelles or component of cells that are involved in body chemistry for a number of specialized fats. Peroxisome biogenesis disorders (PBD) are a group of rare diseases in which patients have genetic defects in the synthesis of peroxisomes. These disorders affect multiple organs including the brain and liver. We used fruitfly (Drosophila melanogaster) to study the metabolism and genetics of peroxisomal biogenesis to gain insight into the disease process. We generated flies with genetic defects in peroxisomes, carefully characterized these flies finding that they are short-lived and have locomotor problems. We then applied global metabolic profiling in these flies, measuring hundreds of biochemical compounds. The analysis pointed to an unexpected link between peroxisomes and sugar metabolism. Guided by this we found our flies were sensitive to low-sugar diet. We then used gene-expression analysis and targeted biochemical profiling in mouse to confirm that carbohydrate alterations also occur in vertebrates. Our work suggests carbohydrate metabolism may be a crucial process to study in patients with PBD.