SLC40A1 and CP single nucleotide polymorphisms in porphyria cutanea tarda patients of mixed ancestry.

Porphyria cutanea tarda (PCT) is a multifactorial disease; clinical expression depends on both genetic and acquired factors. Few studies have examined the connection between PCT and the regulation of iron metabolism genes other than the HFE gene. We selected five polymorphisms in the CYBRD1, CP, SLC40A1, and HAMP genes to determine whether these polymorphisms can act as genetic modulators in patients with sporadic PCT. None of the 29 patients carried the C282Y mutation. Genomic DNA from 29 PCT patients was isolated. Alleles were discriminated using the ABI StepOnePlus Real-Time PCR System using TaqMan Assays. The results were compared with 107 healthy individuals matched for genetic ancestry, gender, and age. European ancestry was prevalent among PCT patients (68.3%). The frequency of the TT genotype of rs13015236 in the SLC40A1 gene was higher in PCT patients (44.8%) than in controls (20.6%) (P < 0.02). The C allele was more frequent among healthy individuals (53.3%) compared with patients (34.5%) (P < 0.01). The rs17838832 G allele of the CP gene was more common among PCT patients (14.3%) compared with controls (4.9%) (P < 0.05). There was no statistically significant difference concerning the three remaining polymorphisms. Our data highlight a possible role for the rs17838832 single nucleotide polymorphisms in CP in causing PCT (higher frequency of the G variant in patients). Regarding the rs13015236 single nucleotide polymorphisms in SLC40A1, the presence of a C allele could protect against PCT.