Dup-24 bp in the CHIT1 Gene in Six Mexican Amerindian Populations

Chitotriosidase (CHIT, EC 3.2.1.14) is an enzyme secreted by activated macrophages with the ability to hydrolyze the chitin of pathogens. The high activity of this enzyme has been used as a secondary biomarker of response to treatment in patients with Gaucher disease (OMIM 230800). Within the world's population, approximately 6% is homozygous and 35% is heterozygous for the most common polymorphism in the CHIT1 gene, a 24-bp duplication (dup-24 bp), with homozygosity of this duplication causing inactivation of the enzyme but without major consequences for health. To determine the frequency of the dup-24 bp CHIT1 gene in indigenous populations from Mexico, 692 samples were analyzed: Purepecha (49), Tarahumara (97), Huichol (97), Mayan (139), Tenek (97), and Nahua (213). We found that the groups were in Hardy-Weinberg equilibrium. The dup-24 bp allele frequency was found to be (in order of highest to lowest) 37% (Mayan), 34% (Huichol and Nahua), 33% (Purepecha), 31% (Tenek), and 29% (Tarahumara).