The present invention relates to methods, kits, probes, and systems for distinguishing between nucleotide variants that are close in proximity on a gene. The methods, kits, probes, and systems can include the use of a small amplicon assay in combination with two unlabeled probes in a high resolution thermal melting analysis of a biological sample containing a locus of interest in order to discern between disease-causing and benign variants that are close in proximity on a gene within the biological sample. The present invention also relates to method of detecting a disease in a patient based on the patient's genotype by determining whether the patient has a disease-causing variant at a locus of interest. The signature melt curves produced by the unlabeled probe tests can be analyzed using HRMA software to distinguish between disease-causing and benign variants that are close in proximity on a gene within the biological sample.