Mannosidosis: assignment of the lysosomal alpha-mannosidase B gene to chromosome 19 in man.

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Abstract
Human .alpha.-mannosidase activity (.alpha.-D-mannoside mannohydrolase, EC 3.2.1.24) from tissues and cultured skin fibroblasts was separated by gel electrophoresis into a neutral, cytoplasmic form (.alpha.-mannosidase A) and 2 closely related acidic, lysosomal components (.alpha.-mannosidase B). Human mannosidosis, an inherited glycoprotein storage disorder, is associated with severe deficiency of both lysosomal .alpha.-mannosidase B molecular forms. Chromosome assignment of the gene coding for human .alpha.-mannosidase B (MANB) was determined in human-mouse and human-Chinese hamster somatic cell hybrids. The human .alpha.-mannosidase B phenotype showed concordant segregation with the human enzyme glucosephosphate isomerase (GPI) (D-glucose-6-phosphate ketolisomerase, EC 5.3.1.9) but discordant segregation with 30 other enzyme markers representing 20 linkage groups. The glucose-phosphate isomerase gene was assigned to chromosome 19 in man. This MANB-GPI linkage and confirming chromosome studies demonstrate assignment of the .alpha.-mannosidase B structural gene to chromosome 19 in man. Since mannosidosis is believed to result from a structural defect in .alpha.-mannosidase B, the mannosidosis mutation is apparently located on chromosome 19 in man.