Detection of point mutations and a gross deletion in six Hunter syndrome patients

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.