J. Inher. Metab. Dis. 22 155 È 162 (1999) SSIEM and Kluwer Academic Publishers. Printed in the Netherlands ( Molecular heterogeneity of Krabbe disease L. FU, K. INUI*, T. NISHIGAKI, N. TATSUMI, H. TSUKAMOTO, C. KOKUBU, T. MURAMATSU and S. OKADA Department of Pediatrics, Faculty of Medicine, Osaka University * Correspondence : Department of Pediatrics, Osaka University, Faculty of Medicine, 2-2 Y amadaoka, Suita, Osaka 565-0871, Japan. E-mail : koji=ped.med.osaka-u.ac.jp MS received 7.04.98 Accepted 14.09.98 Summary : Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive neurodegenerative disorder that a†ects both the central and periph- eral nervous system due to an enzymatic defect of galactocerebrosidase (GALC). Following its cloning, many mutations in the galactocerebrosidase gene have been reported, but the correlation between phenotype and genotype was not clear in many cases. In this study we further investigated the molecular defects in another 10 patients (6 Japanese and 4 non-Japanese), using cultured skin Ðbroblasts, and found 10 mutations, of which 8 were novel, including a nonsense mutation (W647X) and 7 missense mutations (G43R, S52F, T262I, Y319C, W410G, R515H, T652R) in the coding region. Some phenotype-speciÐc mutations were found but the other mutations were private. Mutations report- ed so far have been distributed over the whole GALC gene and it is difficult to speculate on functional domains of the GALC protein and phenotypically spe- ciÐc regions. cell leukodystrophy (GLD ; Krabbe disease ; McKusick 245200) is an auto- Globoid somal recessive inherited neurodegenerative disorder caused by the deÐciency of galactocerebrosidase (GALC, EC 3.2.1.46), the lysosomal enzyme responsible for the degradation of galactocerebroside (Suzuki and Suzuki 1970). Neuropathologically, the disease is characterized by numerous globoid cells, severe loss of myelin, and marked gliosis of the white matter (Austin 1968). These changes result from accumu- lation of the toxic metabolite of psychosine (galactosylsphingosine) (Svennerholm et al 1980). Clinically, most patients with the disease show hypertonicity, irritability and mental retardation within the Ðrst year of life. However, there have been several reports of later onset in childhood and even in adulthood (Kolodny et al 1991 ; Suzuki et al 1995). Recently, the enzyme was puriÐed from human urine and lym- phocytes (Chen and Wenger 1993 ; Sakai et al 1994a), and cloning of the cDNA was reported by two groups (Chen et al 1993 ; Sakai et al 1994b). The 3780 bp cDNA contains an open reading frame of 2007 bp, which encodes 669 amino acids, includ- ing 26 residues of a signal peptide. The 80 È90 kDa precursor protein is processed to 155