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Genetic/Inherited
Disorders:
Terminology:
Inherited = derived from
one’s parents
Congenital = apparent at
birth
Multiple genes are frequently involved in inherited disorders,
either mutation, additions or deletions.
Some genetic disorders may be the result of mutation in
the gametes or during zygote development. In such cases, the parent would
lack the resultant disorder, despite being genetically determined.
Frequency of genetic disorders in the human populous is
around 1/200 hospital admissions.
Homeobox (HOX) genes:
Classes of genes implicated in the patterning of limbs,
verterbrae and craniofacial structures during embryogenesis.
For example: the HOX genes were first identified by genetic
manipulations using Drosophilia, whereby legs appeared in the position
of the antennae.
Alterations of HOX genes produces malformations concordant
with their presumed role in embryonic patterning .
PAX genes:
A family of developmental genes which are highly conserved
throughout evolution.
For example: mutations in the PAX-3 gene produces Waardenburg
syndrome (see later - coat colour mutants).
Overexpression of certain PAX genes is believed to be protooncogenic
and therefore associated with tumourigenesis.
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