Arylsulfatase A lysosomal enzyme Map position 22q13.3

Metachromat ic l eukodys t rophy is an au tosomal recessive d i sorder of myel in metabol i sm caused by a deficiency of the lysosomal enzyme arylsul fa tase A (ARSA) [1]. The ARSA gene has p rev ious ly been local ized to chromosome 22 between 22q13 and qter us ing h u m a n rodent hybr id clones [2]. The human ARSA cDNA probe conta ined the whole coding region and consis ted of a 2.0-kb insert in pBluescript [3]. Fluorescence in situ hybr id iza t ion was as descr ibed in [4], except that no prereassocia t ion was necessary and chromosomes were s ta ined before analysis with both p r o p i d i u m iod ide (as counters ta in) and DAPI (for chromosome identification). Twenty metaphases from a normal male all showed specific label l ing of one or both chromat ids of chromosome 22 in the region ex tending from dis ta l 22q13.31 to 22q13.33. Two non-specific backg round dots were observed. A similar result was shown in a second normal male (15 h igh-resolu t ion metaphases) , conf irming the distal 22q13.3 posi t ion. 1. Gieselmann Vet al. (1995) Hum Mutat 4: 233-242. 2. Geurts van Kissel AHM et al. (1980) Cytogenet Cell Ganet 28: 169-!72. 3. Stein C et al. (1989) J Biol Chem 264: 1252-1259. 4. Callen DF et al. (1990) Ann Gfnft 33: 219-221.