Several patients are reported to have died of basilar artery aneurysm. All were found to have abnormal storage within the lysosomes of arterial smooth muscle fibers. Age of onset does not predict age of death. Patients with the adult form may survive for decades following diagnosis. Muscle weakness may interfere with normal daily activities, and respiratory insufficiency is often associated with sleep apnea.
Death usually results from respiratory failure.
Although specific alleles are identified in certain ethnic groups, no definite genotype-phenotype correlation is present. As noted above, age of onset usually distinguishes the 3 types. Age of onset in the juvenile form may overlap both the adult and infantile forms. Infantile form These patients typically present with weakness and hypotonia in the first 6 months of life, which may manifest as respiratory and feeding difficulties. Early cardiac failure due to LV enlargement and outflow obstruction may lead to respiratory and feeding difficulties as well.