Association of Delta-Aminolevulinic Acid Dehydratase Gene Variant with Serum Level of Alanine Aminotransferase

The enzyme ALAD (delta-aminolevulinic acid dehydratase), encoded by the ALAD gene, catalyzes the synthesis of porphobilinogen. The 177G>C (rs1800435) polymorphism participates in the hereditary deficiency of porphobilinogen synthase to cause acute lead poisoning.

The current study aimed at investigating the allelic frequency of the enzyme ALAD in patients with non-alcoholic fatty liver disease (NAFLD) compared to the control group.

The fatty liver index (FLI) algorithm was used to diagnose NAFLD in participants of a prospective cohort of the Digestive Diseases Research Institute (DDRI). The ALAD genotypes, ALAD1 and ALAD2, were identified in 100 patients with NAFLD and 200 healthy controls using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

The C-allele of ALAD rs1800435 frequency was 5.5% in the group of patients with NAFLD compared to 3.3% in the control group, without significant differences (P = 0.37); however, alleles were in the Hardy-Weinberg equilibrium (P > 0.05). Serum ALT level was considerably higher in the ALAD2 carriers group than in the ones not carrying ALAD2 (29.413.9 vs. 19.410.1, P = 0.041). Nonetheless, each C-allele increased the serum ALT level by 1.24 IU/L (95% confidence interval: 0.22 - 2.67; P = 0.04).

The 177G>C (rs1800435) polymorphism in patients with NAFLD was similar to that of the normal population; however, it can be considered as a risk factor for serum ALT level increase.