What is a key hallmark of dominant lethal alleles in inheritance?

Dominant lethal alleles are characterized by their ability to cause death when present in just one copy of the allele, meaning that individuals who inherit such alleles typically do not survive to reproduce. This is a critical aspect of their inheritance—it leads to the allele being eliminated from the population over time. Since the presence of a dominant lethal allele usually results in the death of the organism before it can reproduce, there is a strong selective pressure against these alleles, leading to their reduction or complete disappearance from the gene pool. Hence, the key hallmark of dominant lethal alleles is indeed that they are typically eliminated from the population, as the affected individuals do not contribute to the next generation.