Structure and organization of the human galactocerebrosidase (GALC) gene.

The deficiency of galactocerebrosidase (GALC; EC 3.2.1.46) is responsible for globoid cell leukodystrophy (GLD, Krabbe disease) in humans and certain animals. This enzyme catalyzes the lysosomal hydrolysis of specific galactolipids including galactosylceramide (galactocerebroside) and galactosylsphingosine (psychosine), among others. Recently we cloned the full-length human GALC cDNA using amino acid sequence information obtained from GALC purified from human urine and brain. In this communication we describe the organization of the human GALC gene. The gene, of nearly 60 kb, consists of 17 exons, which, aside from the first and last, are relatively small, ranging from 39 to 181 nucleotides. The 16 introns range from 247 nucleotides to nearly 12 kb. The 5' untranslated region is GC-rich, containing no perfect CAAT or TATA sequences, similar to genes for other lysosomal proteins. This information will be useful for studies to identify mutations causing low GALC activity in all patients with GLD and to identify the homologous gene in the important animal models.