4]-CL in platelets prepared from blood samples of healthy, adult volunteers after 24 (n = 10) and 48 (n = 10) h, from a group of children (ages 2-10 years; n = 6), and from a group of BTHS patients (n = 4).
Because BTHS, an X-linked recessive disorder with several mitochondrial dysfunctions (12), has been associated with a possible remodeling defect of CL (10), we used our method to establish a procedure for the identification of BTHS patients.
Because CL is an exclusive mitochondrial inner-membrane phospholipid involved in various mitochondrial functions (1-3), markedly decreased CL values can explain the abnormal mitochondrial function observed in BTHS patients.
In a BTHS bloodspot extract, this variation was 47% and 41%, respectively.
For the MLCL/CL ratio as a function of a series of mixes of BTHS and control dried bloodspot punches, the linearity of series A was characterized by [R.
Repeated analysis of bloodspots of a control and a BTHS patient stored either at room temperature or at 4[degrees]C did not show significantly different results over a period of 1 year.
The measurement of bloodspots of 31 different BTHS patients and 215 controls showed that all BTHS patients had a MLCL/CL ratio >0.
Because BTHS patients have high levels of MLCL in combination with low levels of CL, and this is reversed in controls, we investigated whether combination of the inversely correlated parameters in a MLCL/CL ratio could differentiate between the two populations.
Intraassay CV was determined by multiple analyses of bloodspots of each of 3 different BTHS patients and 3 controls within the same series.
Bloodspots from 199 healthy male controls and 7 proven BTHS patients (3 with MLCL/CL ratios close to high normal) were anonymized and randomly assorted by an independent operator so as to simulate a test population.
BTHS bloodspots, however, showed a low abundance for CL and a clearly increased level for MLCL (Fig.
We also investigated whether the BTHS bloodspot assay has the potential to be used as a neonatal screening tool.