Pathological findings in one of two siblings with Sjögren-Larsson Syndrome

Disturbed brain ether lipid metabolism and histology in Sjögren-Larsson syndrome

Sjögren-Larsson syndrome (SLS) is a rare neurometabolic syndrome caused by deficient fatty aldehyde dehydrogenase. Patients exhibit intellectual disability, spastic paraplegia, and ichthyosis. The accumulation of fatty alcohols and fatty aldehydes has been demonstrated in plasma and skin but never in brain. Brain magnetic resonance imaging and spectroscopy studies, however, have shown an abundant lipid peak in the white matter of patients with SLS, suggesting lipid accumulation in the brain as well. Using histopathology, mass spectrometry imaging, and lipidomics, we studied the morphology and the lipidome of a postmortem brain of a 65-year-old female patient with genetically confirmed SLS and compared the results with a matched control brain. Histopathological analyses revealed structural white matter abnormalities with the presence of small lipid droplets, deficient myelin, and astrogliosis. Biochemically, severely disturbed lipid profiles were found in both white and gray matter of the SLS brain, with accumulation of fatty alcohols and ether lipids. Particularly, long-chain unsaturated ether lipid species accumulated, most prominently in white matter. Also, there was a striking accumulation of odd-chain fatty alcohols and odd-chain ether(phospho)lipids. Our results suggest that the central nervous system involvement in SLS is caused by the accumulation of fatty alcohols leading to a disbalance between ether lipid and glycero(phospho)lipid metabolism resulting in a profoundly disrupted brain lipidome. Our data show that SLS is not a pure leukoencephalopathy, but also a gray matter disease. Additionally, the histopathological abnormalities suggest that astrocytes and microglia might play a pivotal role in the underlying disease mechanism, possibly contributing to the impairment of myelin maintenance.

The ichthyoses--pathogenesis and prenatal diagnosis: a review of recent advances

Disturbances in the process of normal cornification leading to pathologic scaling provide the pathophysiologic basis for the ichthyoses. These disturbances may result from either abnormalities in protein metabolism (keratinization) (i.e., the "bricks") or in lipid metabolism (i.e., the "mortar") (Fig. 1). The evidence linking the various ichthyoses to defects in protein or lipid metabolism have been reviewed. It is likely that future advances will lead not only to a more complete understanding of the pathogenesis of these disorders, but also will shed significant light on the normal stratum corneum functions of barrier formation and desquamation, as well as lead the way to more rational and effective therapies. In recent years, prenatal diagnosis has been successfully performed in several of the ichthyoses. It is likely that improvements in our ability to prenatally diagnose those disorders will advance hand-in-hand with further progress in unraveling their underlying causes.