Assignment of sterol carrier protein X/sterol carrier protein 2 to 1p32 and its exclusion as the causative gene for infantile neuronal ceroid lipofuscinosis

In the positional cloning of a disease gene with an unknown protein defect a spectrum of molecular biological methods is applied after linkage has been established. It is reasonable to analyze in detail any relevant candidate gene mapping to the particular chromosomal region. We report here the refined chromosomal assignment of SCP_x;/SCP₂, a gene coding for the protein that is believed to have an important role in lipid metabolism by transporting many kinds of lipid molecules between organelles. This gene represents an excellent candidate gene for infantile neuronal ceroid lipofuscinosis, earlier assigned to 1p32 by us, since lipid metabolism in the patient's brain appears to be significantly disturbed. Expression and structural analyses by Northern, Southern and Western blotting as well as SSCP and direct sequencing did not detect any differences between the cDNAs of patients and controls. Consequently, it is unlikely that a mutation in SCP_x;/SCP₂; is the underlying cause of this severe neurodegenerative disease of childhood.