Authors:
Salih MA, Fakiola M, Abdelraheem MH, Younis BM, Musa AM, ElHassan AM, Blackwell JM, et al.
Authors notes:
BMC infectious diseases. 2014;14(1):662
Keywords:
PKDL, Visceral leishmaniasis, Polymorphisms, RNA expression, IFNG, IFNGR1, Rare variants, Sudan
Abstract:
Little is known about the parasite/host factors that lead to Post Kala-azar Dermal Leishmaniasis (PKDL) in some visceral leishmaniasis (VL) patients after drug-cure.
Studies in Sudan provide evidence for association between polymorphisms in the gene (IFNGR1) encoding the alpha chain of interferon- inverted question mark receptor type I and risk of PKDL.
This study aimed to identify putative functional polymorphisms in the IFNGR1 gene, and to determine whether differences in expression of interferon- inverted question mark (IFNG) and IFNGR1 at the RNA level are associated with pathogenesis of VL and/or PKDL in Sudan.
Ten variants were identified in the 841 bp of sequence, four of which are novel polymorphisms at -77A/G, +10 C/T, +18C/T and +91G/T relative to the IFNGR1 initiation site.
A cluster of conserved non-coding sequences with putative regulatory variants was identified in the distal promoter of IFNGR1.
Variable expression of IFNG was detected in lymph node aspirates of VL patients before treatment, with a marked reduction in expression following treatment.
IFNGR1 expression was also variable in lymph node aspirates from VL patients, with no significant reduction in expression with treatment.
IFNG expression was undetectable in the skin biopsies of PKDL cases, while IFNGR1 expression was also uniformly low.
Uniformly low expression of IFN and IFNGR1 in PKDL skin biopsies could explain parasite persistence and is consistent with prior demonstration of genetic association with IFNGR1 polymorphisms.
Identification of novel potentially functional rare variants at IFNGR1 makes an important general contribution to knowledge of rare variants of potential relevance in this Sudanese population.