Population frequency of the arylsulphatase A pseudo-deficiency allele.
The enzymatic diagnosis of metachromatic leukodystrophy is complicated by the frequent occurrence of the pseudo-deficiency of arylsulphatase A (ASA) enzyme activity. An A to G nucleotide transition in the first polyadenylation signal of the ASA gene results in the loss of its major mRNA species and a greatly reduced level of enzyme activity. This nucleotide change (nucleotide 1620 of the ASA cDNA) is the cause of ASA pseudo-deficiency and is closely linked to another A to G transition (nucleotide 1049), within the ASA gene, which changes Asn350 to serine but which does not affect ASA activity. The distribution of these 2 nucleotide changes has been investigated in 73 unrelated individuals from the Australian population. The two transitions were found together on 14 (9.6%) out of 146 chromosomes. The transition at nucleotide 1620 was not found alone; however, the other transition was found alone on 7 (4.8%) out of the 146 chromosomes. The carrier frequency of the ASA pseudo-deficiency mutation in Australia is thus estimated to be about 20%.
Nelson
P V
PV
Department of Chemical Pathology, Adelaide Children's Hospital, Australia.
Carey
W F
WF
Morris
C P
CP
D000483:Alleles; D001315:Australia; D002553:Cerebroside-Sulfatase / Q000172:deficiency* / Q000235:genetics; D005784:Gene Amplification; D005787:Gene Frequency; D006579:Heterozygote; D006801:Humans; D009154:Mutation
D002553:Cerebroside-Sulfatase