So what is it, exactly? The rotator cuff is a group of four tendons and muscles that converge around the shoulder joint at the top of the humerus, the upper arm bone above the elbow. Together, they form a ''cuff'' that both holds your arm in place and allows it to move in different directions.hile your shoulder is one of your most mobile joints, it's also somewhat weak. Too much stress -- or too many fastballs -- can cause partial tears and swelling in the tendons of the rotator cuff. Abrupt stress may even cause one of the tendons to pull away from the bone or tear in the middle of the tendon.
A gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people.Mutations range in size; they can affect anywhere from a single DNA building block (base pair) to a large segment of a chromosome that includes multiple genes. gene mutation is a permanent alteration in the DNA sequence that makes up a gene, such that the sequence differs from what is found in most people.
mutation(n.) (Biol.) (a) As now employed (first by de Vries), a cellular process resulting in a sudden inheritable variation (the offspring differing from its parents in some well-marked character or characters) as distinguished from a gradual variation in which the new characters become fully developed only in the course of many generations.