 It is characterized by normal development in early childhood, followed by rapid degeneration to a vegetative state.The other forms of ALD vary in terms of onset and clinical severity, ranging from adrenal insufficiency to progressive paraparesis in early adulthood (this form of the disease is typically known as adrenomyeloneuropathy).ALD is caused by mutations in "ABCD1", a gene located on the X chromosome that codes for ALD, a peroxisomal membrane transporter protein.