In the Portuguese population the most frequent form of Gaucher disease is type 
1. The N370S glucocerebrosidase gene mutation accounts for 63% of mutated 
alleles. The frequency of this mutation was accurately determined in the 
Portuguese population, which does not present an Ashkenazi Jewish genetic 
background. A gene frequency of 0.0043, with 95% confidence limits between 
0.0023 and 0.0063, was obtained studying the genomic DNA of 2000 blood cards 
randomly sampled from the national neonatal screening program. On the basis of 
this frequency a significantly high number of homozygotes for the N370S mutation 
should be expected in the Portuguese population. This finding supports the idea 
that the majority of homozygotes for this mutation present a very mild clinical 
phenotype and remain undiagnosed.