Lethal alleles have long been described as the lack of a living homozygous recessive offspring from two carrier parents. Because it is unethical to perform specific crosses in Human to identify which genes may be lethal, we seek to identify several analytical methods to identify a subset of Human gene mutations that could be lethal. Initially, we will eliminate genes associated with known recessive diseases, followed by analysis of genes that are highly conserved, integral to a required pathway, exhibit high transcription levels early in development or that are linked to increased non-disjunction. Once bioinformatically parsed, target genes without deep sequencing coverage or that are high probability targets will be analyzed based on lack of homozygotes within the Human population.