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?

67% (5,754/8,560) is the fraction of Mendelian phenotypes for which the underlying gene is known.

21% (4,109/19,580)

of human genes are known to underlie a Mendelian phenotype.

24% (982/4,109) 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-9-2021