A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its earliest point.
A zygotic lethal gene is a mutated (changed) version of a normal gene essential to the survival of the zygote. The extent of the mutation can range from a change in a single base in the DNA to deletion (loss) of the entire gene.
‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.
Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]
- Z chromosome
A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.
- FAO deficiency
FAO deficiency: Also known as the Sjogren-Larsson syndrome, this is a genetic (inherited) disease usually characterized by a triad of clinical findings consisting of ichthyosis (thickened fish-like skin), spastic paraplegia (spasticity of the legs) and mental retardation. The skin changes in the Sjogren-Larsson syndrome are similar to those in congenital ichthyosiform erythroderma, a genetic disease […]
- Major gene
A gene that is necessary and sufficient by itself to cause a condition. For example, the APC gene is a major gene for colorectal cancer.