The great white shark is notable for its size, with mature female individuals growing up to 6.1 m (20 ft) in length and 1,950 kg (4,300 lb) in weight. However most are smaller, males measuring 3.35 to 3.96 m (11 ft 0 in to 13 ft 0 in) and females 4.57 to 4.88 m (15 ft 0 in to 16 ft 0 in) on average.
For most ALS genes, only one mutated copy is needed to cause disease. This is called a âdominantâ gene. For other genes, both copies must be mutated to cause disease. This is called a ârecessiveâ gene. During formation of eggs and sperm, gene pairs split up, so that an egg (or sperm) contains only one gene copy.
Researchers still don't know exactly what causes motor neurons to die with ALS. Gene changes, or mutations, are behind 5% to 10% of ALS cases. More than 12 different gene changes have been linked to ALS. One change is to a gene that makes a protein called SOD1.