Springer Online Journal Archives 1860-2000
Abstract We used polymerase chain reaction (PCR)/single-strand conformation polymorphism analysis and direct sequencing of the coding region of the β-glucuronidase cDNA and gene to detect mutations causing β-glucuronidase enzyme deficiency in five MPS VII patients. Four patients presented with hydrops fetalis, one with an early infantile form of the disease. Genetic heterogeneity of MPS VII alleles was further confirmed in this study. Recurrent mutations were observed in patients of related origin. Previously unknown alleles detected were R110X, F361Δ9, 1270 + 1G→A, S52F and 1480Δ4. Reverse transcription/PCR analysis of the 1270 + 1G→A messenger showed aberrant splicing: inclusion of intron 7 or skipping of exons 6–7 and 9. Messenger RNA transcribed from the R110X and 1480Δ4 alleles was unstable. We detected a 2154A/G change in the 3′ non-coding region of the gene, in the neighbourhood of the two consensus polyadenylation sites. 3′-Rapid amplification of cDNA ends/ PCR of fibroblast cDNA revealed equal usage of two alternative polyadenylation sites. The 2154A/G substitution did not influence adenylation-site choice, nor the amount of stable messenger produced. The finding that 2 out of 30 normal controls carried the 2154G allele indicated that the 2154A/G substitution is a harmless polymorphism. The S52F and F361Δ9 cDNAs were constructed in vitro and used to transfect COS cells transiently. Both mutations completely abolished enzyme activity.
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