3-HYDROXY-3-METHYLGLUTARYL COA LYASE (HL) - MOUSE AND HUMAN HL GENE (HMGCL) CLONING AND DETECTION OF LARGE GENE DELETIONS IN 2 UNRELATED HL-DEFICIENT PATIENTS

3-hydroxy-3-methylglutaryl CoA lyase (HL, EC 4.1.3.4) catalyzes the cl eavage of 3-hydroxy-3-methylglutaryl CoA to acetoacetic acid and acety l CoA, the final reaction of both ketogenesis and leucine catabolism. Autosomal-recessive HL deficiency in humans results in episodes of hyp oketotic hypoglycemia and coma, Using a mouse HL cDNA as a probe, we i solated a clone containing the full-length mouse HL gene that spans ab out 15 kb of mouse chromosome 4 and contains nine exons. The promoter region of the mouse HL gene contains elements characteristic of a hous ekeeping gene: a CpG island containing multiple Sp1 binding sites surr ounds exon 1, and neither a TATA nor a CAAT box are present. We identi fied multiple transcription start sites in the mouse HL gene, 35 to 9 bases upstream of the translation start codon. We also isolated two hu man HL genomic clones that include HL exons 2 to 9 within 18 kb. The m ouse and human HL genes (HGMW-approved symbol HMGCL) are highly homolo gous, with identical locations of intron-exon junctions. By genomic So uthern blot analysis and exonic PCR, we found 2 of 33 HL-deficient pro bands to be homozygous for large deletions in the HL gene. (C) 1996 Ac ademic Press, Inc.