Analysis of cDNA molecules is not suitable for the molecular diagnosis of Mucopolysaccharidosis type I.

Nonsense-mediated decay (NMD) is a mechanism of the recognition and degradation of messenger RNA containing a premature stop codon. Nonsense mutations are the main mutations that lead to Mucopolysaccharidosis type I. To determine the effect of NMD on correct genotyping based on cDNA sequencing, we standardized the sequencing from alpha-L-iduronidase gene cDNA molecules and validated this process for a group of patients whose mutations had been previously identified by DNA analysis. Although the whole gene could be amplified in 5 polymerase chain reactions, cDNA proved unsuitable for molecular analysis as patients bearing splice site and nonsense mutations were not genotyped.