A single mutation can affect all downstream functional domains if a premature stop codon or framing error results; such a mutation can result in a completely unusable (or unsynthesizable) androgen receptor protein. The steroid binding domain is particularly vulnerable to the effects of a premature stop codon or framing error, since it occurs at the end of the gene, and its information is thus more likely to be truncated or misinterpreted than other functional domains.Other, more complex relationships have been observed as a consequence of mutated AR; some mutations associated with male phenotypes have been linked to male breast cancer, prostate cancer, or in the case of spinal and bulbar muscular atrophy, disease of the central nervous system. The form of breast cancer seen in some men with PAIS is caused by a mutation in the ARs DNA-binding domain. This mutation is thought to cause a disturbance of the ARs target gene interaction that allows it to act at certain additional targets, possibly in conjunction with the estrogen receptor protein, to cause cancerous growth. The pathogenesis of spinal and bulbar muscular atrophy (SBMA) demonstrates that even the mutant AR protein itself can result in pathology. The trinucleotide repeat expansion of the polyglutamine tract of the AR gene that is associated with SBMA results in the synthesis of a misfolded AR protein that the cell fails to proteolyze and disperse properly. These misfolded AR proteins form aggregates in the cell cytoplasm and nucleus.
Carotid artery dissection is a separation of the layers of the artery wall supplying oxygen-bearing blood to the head and brain and is the most common cause of stroke in young adults. (Dissection is a blister-like de-lamination between the outer and inner walls of a blood vessel, generally originating with a partial leak in the inner lining. )Dissection may occur after physical trauma to the neck, such as a blunt injury (e.g. traffic collision), strangulation, but may also happen spontaneously. Signs and symptoms
The signs and symptoms of carotid artery dissection may be divided into ischemic and non-ischemic categories:Non-ischemic signs and symptoms:

Localised headache, particularly around one of the eyes
Neck pain
Swollen tongue
Decreased pupil size with drooping of the upper eyelid (Horner syndrome)
Pulsatile tinnitusIschemic signs and symptoms:

Temporary vision loss
Ischemic stroke

Causes
The causes of internal carotid artery dissection can be broadly categorized into two classes: spontaneous or traumatic.