IDENTIFICATION OF A FERRITIN LIGHT-CHAIN PSEUDOGENE NEAR THE GLYCEROLKINASE LOCUS IN XP21 BY CDNA AMPLIFICATION FOR IDENTIFICATION OF GENOMIC EXPRESSED SEQUENCES

We used cDNA amplification for identification of genomic expressed seq uences (CAIGES) to identify genes in the glycerol kinase region of the human X chromosome. During these investigations we identified the seq uence for a ferritin light chain (FTL) pseudogene in this portion of X p21. A human liver cDNA library was amplified by vector primers, label ed, and hybridized to Southern blots of EcoRI-digested human genomic D NA from cosmids isolated from yeast artificial chromosomes in the glyc erol kinase region of Xp21. A 3.1-kb restriction fragment hybridized w ith the cDNA library, was subcloned and sequenced, and a 440-bp intron less sequence was found with strong similarity to the FTL coding seque nce. Therefore, the FTL pseudogene that had been mapped previously to Xp22.3-21.2 was localized specifically to the glycerol kinase region, The CAIGES method permits rapid screening of genomic material and will identify genomic sequences with similarities to genes expressed in th e cDNA library used to probe the cloned genomic DNA, including pseudog enes. (C) 1997 Academic Press.