Background: The frequency of pyruvate kinase (PK) deficiency, an autosomal recessive defect, is approximately 3 per 10,000 individuals in Shiraz and surrounding areas, and is increased due to high consanguinity marriage frequency. The purpose of this study is to obtain data on the frequency and spectrum of gene mutation of PK in newborns, from Shiraz and surrounding areas.

Materials and Methods: Two hundred eleven neonates with neonatal jaundice were studied for erythrocyte pyruvate kinase activity using the method recommended by International Committee for Standardization in Hematology (ICSH).

Results: In 22 the PK enzyme activity was below 60%, where the erythrocyte PK activity from 35 healthy cord bloods ranged from 3.9 – 9.8 IU/g Hb. Genomic DNA analysis for PK-R gene mutation was examined in 12 out of 22 cases (heterozygote 3.8%, 95% CI=0.012-0.064 homozygous 1.8%, 95% CI=0.001-0.036). All mutations in four homozygote and 8 heterozygote neonates in this cohort have been reported from the region previously, except for mutation G1675C that has not been found before. Therefore, the rate of recurrence of PK-R gene defect is 4 times more frequent in those with neonatal jaundice in comparison with the regional frequency (0.038).

Conclusion: Erythrocyte enzymopathies, especially PK deficiency, should be considered in the differential diagnosis of non-immune hemolytic anemia as well as for genetic counseling in our area.