Abstract

We have used screening with the polymerase chain reaction and chemical mismatch detection of amplified cDNA to detect and characterize deletions and point mutations in six Hunter Syndrome patients. A high degree of mutational heterogeneity was observed. The first patient is completely deleted for the gene coding for alpha-L-iduronate sulfate sulfatase, while the second has a point mutation that creates a stop codon. The third patient shows a point mutation that creates a novel splice site that is preferentially utilized and results in partial loss of one exon in the RNA. Patients 4, 5, and 6 have point mutations resulting in single amino acid substitutions. Four of the six single-base changes observed in this study were examples of transitions of the highly mutable dinucleotide CpG to TpG. This study has demonstrated a procedure capable of detecting all types of mutation that affect the function of the IDS protein and should enable direct carrier and prenatal diagnosis for Hunter syndrome families.