Ethnicity affects the distribution of delta-aminolevulinic acid dehydratase (ALAD) genetic variants.
BACKGROUND
delta-Aminolevulinic acid dehydratase (ALAD) catalyzes the second step of heme synthesis. The ALAD gene shows a polymorphism (G-to-C transversion at position 177) leading to 2 alleles (ALAD1 and ALAD2) and 3 phenotypes (ALAD 1-1, ALAD 1-2 and ALAD 2-2). This polymorphism has been shown to affect lead toxicity and the risk of meningioma. In addition, there is little evidence showing interethnic differences in the distribution this polymorphism, especially in heterogeneous populations such as the present-day Brazilian population. We examined the distribution of genetic variants of the G177C ALAD polymorphism in black and white Brazilians.


METHODS
We studied 115 subjects self-reported as black and 119 subjects as white (total N=234; 135 men and 99 women; age range: 18-60 years). Genomic DNA was extracted from venous blood and the genotypes for the ALAD polymorphism were determined by PCR followed by RFLP digestion and gel electrophoresis.


RESULTS
We found a notable interethnic disparity in the distribution of G177C ALAD genotypes and alleles. The ALAD2 allele was more common in whites (12%) than in blacks (4%) (P<0.05). Correspondingly, the heterozygote (ALAD 1-2) or homozygote variant (ALAD 2-2) genotypes for this polymorphism were more common in whites than in blacks (P<0.05).


CONCLUSIONS
The significant interethnic differences in the distribution of G177C ALAD variants found in the Brazilian population is consistent with differences previously reported in other countries. These findings may help us understand the interethnic disparities in susceptibility to lead toxicity and brain tumors.
Montenegro
Marcelo F
MF
Department of Pharmacology, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil-FMRP-USP, Av. Bandeirantes, 3900, Monte Alegre, CEP 14049-900, Ribeirao Preto, SP, Brazil.
Barbosa
Fernando
F
Sandrim
Valeria C
VC
Gerlach
Raquel F
RF
Tanus-Santos
Jose E
JE
D000293:Adolescent; D000328:Adult; D000483:Alleles; D001938:Brazil / Q000208:ethnology; D005260:Female; D014644:Genetic Variation / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D000623:Porphobilinogen Synthase / Q000235:genetics*
D000623:Porphobilinogen Synthase