Prader-Willi syndrome is caused by a missing gene on chromosome 15. Normally, parents each pass down a copy of this chromosome. The defect can occur in a couple of ways: The father's genes are missing on chromosome 15; There are defects or problems with the fatherâs genes on chromosome 15
poison meaning, definition, what is poison: a substance that can make people or animals ill or kill them if they eat or drink it: . Learn more.
Poisonous describes the deleterious effect of a chemical upon a living system. Poisonous chemicals are quantified in their effect by the quantity required to kill 50% of a givâ¦en organism by body mass (Median Lethal Dose or LD50). US DOT defines poisonous as a material having an LD50 oral, rat of 200 mg/Kg or less.