LETHAL ALLELES

=Lethal Alleles= [image:http://i.imgur.com/kCGgKP0.png] Achondroplasia is a type of dwarfism caused by the presence of a dominant allele (A). However, the presence of two dominant alleles is lethal. Individuals that are homozygous dominant (AA) are never born (miscarried). As phenotype ratios usually only include individuals who survive to birth, the resulting ratios are altered. A cross between two individuals with dwarfism (Aa x Aa) would produce the following offspring [image:http://i.imgur.com/2r0f6V8.png?1] [image:http://i.imgur.com/z41hX3W.png]