Monolysocardiolipin/cardiolipin ratio of intact leukocytes as novel tool for the screening of Barth Syndrome

Abstract

Unambiguous diagnostic testing for Barth Syndrome (BTHS) is routinely performed by determination of the relative amounts and distribution of monolysocardiolipin (MLCL) and cardiolipin (CL) species, confirmed by TAZ gene sequencing or vice versa. Molecular analysis of the TAZ gene is a powerful tool for the diagnosis of BTHS but can lead to false negative results when mutations are present in regulating or relevant non-coding sequences. Because of this, CL abnormalities in BTHS have been recognised to be an important biomarker for the diagnosis. Recently we described a novel MALDI-TOF-MS approach for the lipid analysis of intact mitochondria and bacterial cells that does not require extraction and separation steps, leading to a fast and accurate, qualitative and quantitative determination of the cardiolipin levels using a very small amount of sample. Therefore we have used MALDI-MS to develop a new, fast, easy, inexpensive and non-invasive method for the diagnosis of BTHS. The method needs only 1 ml of whole blood; leukocytes are easily isolated by eliminating erythrocytes with dextran sedimentation followed by hypotonic lysis of residual erythrocytes. Collected leukocytes are then easily analysed by MALDI-MS as intact cells, skipping the lipid extraction procedure. Data show that BTHS leukocytes can be easily identified by their MALDI-TOF-MS lipid fingerprints, which are consistently different from controls.