β‐Glucuronidase P408S, P415L allele in a Mexican population: population screening in Guadalajara and prenatal diagnosis

Recently we identified a P408S, P415L allele of β-glucuronidase in several Mexican patients with mucopolysaccharidosis type VII (Sly syndrome) and presented evidence that both mutations are required to produce the MPS VII allele (Islam et al., 1996). In an attempt to determine whether either of these mutations exists as a benign polymorphism among Mexicans, we developed a PCR method to screen simultaneously for both mutations and used it to screen a population sample of 187 Mexican individuals in the Guadalajara area. all from the north-western states of Mexico. Neither mutation was present in 374 alleles studied. In addition. we had the opportunity to carry out prenatal diagnosis in a fetus at risk for homozygosity for this MPS VII allele at the 15th week of gestation using enzymatic assays as well as by analysis of genomic DNA isolated from cultured amniotic fluid cells. The fetus was found to be heterozygous for the P408S, P415L allele. The newborn's heterozygosity was confirmed after birth by enzyme assays on plasma and leukocytes, and by analysis of DNA from leukocytes.