Table 1.

Definitions of Terms Used to Characterize Discovery Type

Term	Definition
Phenotype	the collection of observable or measurable traits of an individual
Known phenotype	a Mendelian phenotype with a MIM number
Explained, known phenotype	a Mendelian phenotype with a MIM number and for which a causal variant(s) in one or more genes is known
Unexplained, known phenotype	a Mendelian phenotype with a MIM number and for which no causal variant(s) has been reported
New phenotype	a Mendelian phenotype without a MIM number (MIM number assigned thereafter)
Known gene	a gene in which a causal variant(s) has been previously associated with a Mendelian phenotype
Novel gene	a gene in which a causal variant(s) has not been previously associated with a Mendelian phenotype
Known gene; explained, known phenotype	a Mendelian phenotype with a MIM number and for which a causal variant was found in a gene previously associated with the same phenotype
Novel gene; unexplained, known phenotype	a Mendelian phenotype with a MIM number, for which no causal variant(s) has been reported, and for which a causal variant was discovered in novel gene
Novel gene; new phenotype	a Mendelian phenotype without a MIM number and for which a causal variant(s) was found in a gene in which a causal variant(s) has not been previously associated with a Mendelian phenotype (MIM number assigned thereafter)
Known gene; unexplained, known phenotype	a Mendelian phenotype with a MIM number, for which a causal variant(s) has not been reported, and for which a causal variant was found in a gene previously associated with a different phenotype
Known gene; new phenotype	a Mendelian phenotype without a MIM number and for which a causal variant was found in a gene previously associated with a different phenotype (MIM number assigned thereafter)
Phenotype expansion	expansion of the spectrum of clinical characteristics of an explained, known Mendelian phenotype