What is an example of an allele that is lethal in a homozygous and can still exist in a gene pool??

Question

What is an example of an allele that is lethal in a homozygous and can still exist in a gene pool??

Answer 1

Cystic fibrosis.

Answer 2

emucompboy is right, your teacher wants Sickle Cell Anemia. Many lethal  (or lethal in the absence of medical intervention) disorders are caused by homozygous recessive alleles (Cystic Fibrosis, Phenylketonuria, Tay-Sachs disease), but Sickle Cell is special: Evidence suggests that individuals who are heterozygous for Sickle Cell (i.e. carry one normal allele and one mutant allele) have increased resistance to Malaria. Population studies have shown that there is a statically significant increase in frequency of the recessive Sickle Cell allele in areas of the world where malaria is endemic. This represents an almost unique situation (at least in humans) where the heterozygous in a population are at an advantage over both homozygous wild type and homozygous recessive individuals.

Answer 3

Another example is the Achondroplasia dwarfism allele - a mutated version of the FGFR3 gene.

This gene is involved in growth factor detection, and if it is mutated to the Achondroplasia allele, then you express defects in cartilage production, and have the most common form of dwarfism.

All achondroplasiac dwarfs are heterozygous (it is an autosomal dominant allele). If you are homozygous for the allele, it is embryonic lethal.

Answer 4

All of them, but your teacher wants you to answer

sickle cell anemia