Complement C4 Gene Copy Number Variation Genotyping by High Resolution Melting PCR.

BACKGROUND: Complement C4 gene copy number variation plays an important role as a determinant of genetic susceptibility to common diseases, such as systemic lupus erythematosus, schizophrenia, rheumatoid arthritis, and infectious diseases. This study aimed to develop an assay for the quantification of copy number variations in the C4 locus. METHODS: the assay was based on a gene ratio analysis copy enumeration (GRACE) PCR combined with high resolution melting (HRM) PCR. The test was optimized using samples of a known genotype and validated with 72 DNA samples from healthy blood donors. RESULTS: to validate the assay, standard curves were generated by plotting the C4/RP1 ratio values against copy number variation (CNV) for each gene, using genomic DNA with known C4 CNV. The range of copy numbers in control individuals was comparable to distributions observed in previous studies of European descent. CONCLUSIONS: the method herein described significantly simplifies C4 CNV diagnosis to validate the assay.

A Knockout IFNL4 Variant Is Associated With Protection From Sexually Transmitted HIV-1 Infection.

An interferon λ4 gene (IFNL4) knockout allele (rs368234815; TT) is associated with spontaneous and IFN-α-dependent cure of hepatitis C virus infection. The role of this polymorphism in the susceptibility to human immunodeficiency virus type 1 (HIV-1) infection is controversial. This study aimed to assess the association of this knockout IFNL4 variant and sexually transmitted HIV-1 infection. A total of 228 HIV-1-positive individuals and 136 HIV-exposed seronegative individuals were investigated for their association with IFNL4 rs368234815 genotypes. The IFNL4 ΔG functional allele is associated with increased susceptibility to HIV-1 infection through the sexual route (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.2-3.6; P = .004). A meta-analysis including a population of injection drug users suggests a codominant mode of inheritance of this risk factor (OR, 2.0; 95% CI, 1.3-3.2; P = .001).