Recessives from both parents can be Lethal.

• Position: Genetic Disorders - Brief article

Humans carry on average one to two mutations that, if inherited from both parents, can cause severe genetic disorders or death before reaching reproductive age, report scientists from the University of Chicago (III.). The estimate is based on an analysis of the genealogy of an isolated founder population with more than 1,500 living descendants.

Every person carries two copies of all of their autosomal genes, inheriting one copy from the mother and one from the father. A large number of genetic diseases are caused by recessive mutations, which are harmless when present in one copy of a gene, but can lead to severe or lethal disorders if present in both. Recessive disease mutations are much more common than mutations that cause disease when present on only one copy of a gene, but the rate at which they appear in a general population has been unclear.

To investigate how many recessive lethal mutations are carried by humans on average, Ziyue Gao, a graduate student in the Genetics, Genomics and Systems Biology program, and her colleagues...