Mendelian Traits by the Numbers

A phenotype is the collection of observable or measurable traits of an individual. Phenotypes that result from changes (i.e., variants) in a single gene (i.e., monogenic) and that can be transmitted from parents to offspring in Mendelian patterns, such as autosomal dominant, autosomal recessive, X-linked, are known as Mendelian phenotypes.


 What is known about the genomic basis of Mendelian phenotypes?

64% (5,048/7,926)

is the fraction of Mendelian phenotypes for which the underlying gene is known.

18% (3,553/19,580)

of human genes are known to underlie a Mendelian phenotype.

24% (856/3,553)

of genes known to underlie a Mendelian phenotype cause two or more different phenotypes.

Counts are based on calculations by the Genome Sequencing Program Coordinating Center using data extracted from OMIM ( on September-16-2018.