Abnormal Meibum Is Associated With SREBF1 Mutation And IFAP Syndrome-2

Abstract The X-linked Ichthyosis Follicularis, Alopecia, and Photophobia syndrome type-2 (IFAP-2), is a condition that has been linked to a c.1579C>T mutation in the SREBF1 gene. However, the molecular implications of the mutation in Meibomian glands (MG) remain unknown. The goals of our project were to elucidate the biochemical factors associated with IFAP-2 and develop approaches for unbiased diagnosing this condition. Meibum samples were collected from normal subjects and a patient with IFAP-2-like signs and symptoms. Genetic analysis of the IFAP-2 subject revealed a c.1579C>T (p.Arg527Cys) mutation in the SREBF-1 gene that was previously associated with IFAP-2. The meibum samples were analyzed using liquid chromatography–mass spectrometry (LC-MS), and the data were compared using multivariate statistical approaches. The LC-MS provided detailed information on the differences between the Meibomian lipid profiles of normal subjects and the IFAP-2 patient, specifically in saturated and unsaturated wax esters (SWE and UWE). Our data showed that IFAP-2 meibum was enriched with SWE which increased the SWE/UWE ratio to highly abnormal levels. The higher melting temperature of SWE compared to that of UWE correlated well with poor expressibility and abnormal thickness of IFAP-2 meibum. Thus, our study demonstrated possible links between the p.Arg527Cys mutation in SREBP1 protein, upregulation of SWE in the IFAP-2 meibum, and MG Dysfunction. It also showed that LC-MS can be used as a sensitive and informative tool to reveal minute differences in the Meibomian lipidomes of the subjects with MG Dysfunction, and identify molecular markers of the conditions. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study was supported in part by an R01 grant EY027349 from the National Institutes of Health to Dr. I. A. Butovich, and by a Challenge Grant from the Research to Prevent Blindness (New York, NY) to the Department of Ophthalmology of The University of Texas Southwestern Medical Center. The funding organizations had no role in the design and conduct of the study. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Institutional Review Board of the UT Southwestern Medical Center in Dallas, TX, USA I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Footnotes ↵* Visiting Assistant Professor; current affiliation: Centro Oftalmologico de Valencia, Avenue Bolivar Norte, Edificio Torre Venezuela, Valencia, Carabobo, Venezuela. A new Figure 3 has been added. A discussion on the potential mechanism of the abnormal IFAP-2 meibum formation and its connection to the SREBF1 c.1579C>T mutation is presented. New references have been added. Data statement All relevant data are included in the manuscript. Additional data can be requested from the corresponding author.