The rs216009 single-nucleotide polymorphism of the gene is associated with phantom tooth pain.

Phantom tooth pain (PTP) is a rare and specific neuropathic pain that occurs after pulpectomy and tooth extraction, but its cause is not understood. We hypothesized that there is a genetic contribution to PTP. The present study focused on the gene, which encodes the α1C subunit of the Ca1.2 L-type Ca channel (LTCC) that has been reported to be associated with neuropathic pain in previous studies. We investigated genetic polymorphisms that contribute to PTP. We statistically examined the association between genetic polymorphisms and PTP vulnerability in 33 patients with PTP and 118 patients without PTP but with pain or dysesthesia in the orofacial region. From within and around the gene, 155 polymorphisms were selected and analyzed for associations with clinical data. We found that the rs216009 single-nucleotide polymorphism (SNP) of the gene in the recessive model was significantly associated with the vulnerability to PTP. Homozygote carriers of the minor C allele of rs216009 had a higher rate of PTP. Nociceptive transmission in neuropathic pain has been reported to involve Ca influx from LTCCs, and the rs216009 polymorphism may be involved in expression, which regulates intracellular Ca levels, leading to the vulnerability to PTP. Furthermore, psychological factors may lead to the development of PTP by modulating the descending pain inhibitory system. Altogether, homozygous C-allele carriers of the rs216009 SNP were more likely to be vulnerable to PTP, possibly through the regulation of intracellular Ca levels and affective pain systems, such as those that mediate fear memory recall.