What is a rare genetic variant?

Definition. Rare variants are alternative forms of a gene that are present with a minor allele frequency (MAF) of less than 1%.

Why study rare variants?

Rare variants can explain additional disease risk or trait variability. An increasing number of studies are underway to identify trait- and disease-associated rare variants.

How do you identify rare variants?

Sequencing can uncover the full spectrum of genetic variation and is the optimal approach to identifying rare genetic variants for association studies.

What is a genetic burden test?

In the gene-based burden testing approach, the number of individuals carrying variants in a given gene is compared between disease case and control cohorts. Typically, sequencing data are filtered for rare, protein-altering variants, as these are believed to be more likely to cause a rare monogenic disorder.

What are common genetic variants?

Common genetic variants are described as a 5% frequency differential between diseased vs. matched control populations. This theory was recently supported by an epidemiology paper stating that about 50% of genetic risk for autism resides in common variants.

Are gene variants common?

Most variants do not lead to development of disease, and those that do are uncommon in the general population. Some variants occur often enough in the population to be considered common genetic variation. Several such variants are responsible for differences between people such as eye color, hair color, and blood type.

Are SNPs rare?

SNPs occur normally throughout a person’s DNA. They occur almost once in every 1,000 nucleotides on average, which means there are roughly 4 to 5 million SNPs in a person’s genome. These variations occur in many individuals; to be classified as a SNP, a variant is found in at least 1 percent of the population.

What does genetic burden mean?

1. The number of diseases and deaths that occur as a result of inherited traits. 2. The cost to the genome of mutations or selection pressure that eliminate alleles from it.

What are the 2 types of genetic variation?

Regardless of the molecular mechanisms or processes that generated the genetic variations, they can be broadly classified as either somatic or germline variations depending on whether they arose from mitosis or meiosis, respectively.