Gaucher Disease(GD) is caused by β-glucosidase(GBA) deficiency and chitotriosidase(CT) is increased in these patients. The dosage of GBA (leukocytes) and CT(plasma) are considered as standard for diagnosis. This measure can also be held in dried blood spots(DBS) just as screening. This study aims to establish reference values of GBA and CT activity in leukocytes, plasma and DBS and its correlation. We used heparinized-blood of 18 healthy-volunteers(HV), 18 GD-patients and 4 carriers. The techniques used 4-Metilumbeferil substrates. GBAwere incubated for 60 min(leukocytes) or 5 h(DBS) and CT for 15 min(plasma) or 30 min(DBS), at 37°C and stopped with pH10.3 buffer. Reactions were read at 365 and 450 nm spectrofluorimeter. The reference values for GBA in leukocytes raged from 8.6 to 18.4(HV), 0.4 to 9.0(carriers) and 0.0 to 4.6 nmol/h/mg protein(GD); while in DBS were 2.7 to 7.1(HV), 2.6 to 6.2(carriers) and 0.2 to 2.6 nmol/h/mL(GD). CT in plasma ranged from 0 to 246.9(HV), 165.1 to 338.7(carriers) and 0 to 49.58 nmol/h/mL(GD) and in DBS from 4.6 to 44.5(HV), 4.5 to 21.4 (carriers) and 0.0 to 2249.5 nmol/h/mL(GD). For both enzymes, the correlation was significant with p<0.0001, r=0.78(GBA) and r=0.89(CT). The results showed that DBS enzyme assay are reliable and can be useful as screening methods for high-risk populations. Background: Gaucher disease is an autosomal recessive disorder of lysosomal degradation of glucosylceramide. It results in a progressive accumulation of glucosylceramide in the lysosomes, leading to hepatosplenomegaly, anemia, thrombocytopenia and various skeletal complications. The most common mutation is the substitution A to G at nucleotide position 1226, which produces aAsn-Ser change at amino acid 370. There is variable frequency of this mutation: in Ashkenazic Jews carrier frequency 1: 15; 1 in 100 people in the United States. Objectives: Detect carrier frequency of mutation N370S in Latvian population Material and Methods: We studied 150 volunteers, aged 19-25 years. DNA was extracted from whole blood and purified by standard phenol/ chloroform extraction protocol. The presence of mutation N370S in gene GBA was analyzed using PCR with subsequent restriction enzyme XhoI digestion and detected in polyacrylamide gel. Results: One patient out of 150 was heterozygous for mutation N370S. Estimated Gaucher disease frequency when patients are homozygous for mutation N370S is 1 : 90 000 Conclusions: 1. Carrier frequency of mutation N370S in Latvian population is low. 2. Gaucher disease in Latvian population may be caused by other mutations 3. To obtain more precise results about mutation frequency control population should be enlarged.