Definition of Trait Trait: In genetics, a trait refers to any
genetically determined characteristic. In technical terms, a
genetic trait is amenable to segregation analysis rather than
quantitative analysis. A dominant lethal trait is a trait that
is expressed if present in the genome and therefore precludes
having descendants. All such cases must necessarily be sporadic
and must represent new mutations, not inherited ones (because a
potential parent with the trait would die before being able to
pass it along). A mendelian trait is one that segregates in
accordance with the laws of genetics set forth by Gregor Mendel.
Sickle cell trait is a mendelian trait. It refers to the
situation in which a person has one copy (and one copy only) of
the gene for sickle cell but does not have sickle cell disease
(which requires two copies of the sickle cell gene). If two
people with sickle cell trait have children together, each of
their children has a one in four chance (25%) of having sickle
cell disease. A nonpenetrant