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 de
termined in the Portuguese population, which does not present an Ashke
nazi Jewish genetic background. A gene frequency of 0.0043, with 95% c
onfidence limits between 0.0023 and 0.0063, was obtained studying the
genomic DNA of 2000 blood cards randomly sampled from the national neo
natal screening program. On the basis of this frequency a significantl
y 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 clinica
l phenotype and remain undiagnosed.