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Rare allele:

At a given locus, the nucleotide seen least frequently in a given population. An allele is considered rare when it has a frequency of less than 1% in a given population.

Rearrangement:

A structural alteration of a chromosome which results in an abnormal configuration, such as an inversion or translocation, and may interrupt a gene sequence. Chromosomal rearrangements are typically identified on a karyotype.

Recessive:

A characteristic, trait, or disorder which is phenotypically expressed when two variant alleles are present.

Reference genome:

The DNA sequence of an organism created from the combined DNA sequences of multiple individuals. It is considered to represent the common genetic information in humans and is a useful to for genetic analyses.

Resequencing:

The sequencing of a specific exon or genomic region for the identification of DNA variants. Often performed to screen a large population for a gene of interest, or to confirm a DNA variant identified by massively parallel sequencing.

RFLP:

Restriction fragment length polymorphism

RT-qPCR:

Reverse transcriptase quantitative PCR